BUILDING (CONSTRUCTION) REGULATIONS

BUILDING (CONSTRUCTION) REGULATIONS

BUILDING (CONSTRUCTION) REGULATIONS

ARRANGEMENT OF REGULATIONS

Regulalion PART I age

PRELIMINARY

1. Citation ................................. ... ... . ... 7
2. Interpretation ........................... ... ... ... ... ... ... B 7
3. Materials ................................ ... ... B 9
4. British Standard Specification or British Standard Code of Practice ... ... B 9
5. Permissible stresses not to be exceeded ... ... ... ... ... ... ... B 9
6. Dispersion of load ...................... ... ... ... ... ... ... B 10
7. Overloading ................... .......... ... ... B 10
8. Support for adjoining and other buildings ... ... ... ... B 10

PART II

MATERIALS

9. Bricks and building blocks..........11 ... . ... ... ... ... ... ... B 10
10. Cement ...................................B 11
11. Lime ........................................
12. Sand .................................. B 121
13. Red earth ................................ ... ... ... ... ... B 12
14. Water .. ................................B 12
15. Cement mortar .............................. I B 12
.......................................... . ... ..
16. Cement-lime mortar .......................B 12
17. Lime mortar .............................. ... B 13
18. Aggregate .................................. ... ... ... ... ... B 13
19. Concrete . ............................ ... ... ... ... ... B 14
20. Reinforcement for concrete B 17
21. Structural and rivet steel
.......................................B 17
22. Timber ...................................B 18
2R. Materials for damp-proofing ................. ... ... . ... ... B 18

PART III

LOADS

24. Buildings to be designed for wind effects ... ... ... ... ... ... ... B 19
25. Design loads. ............................ ... ... . ... ... B 19
26. Test load ........................... ... ... ... ... ... ... ... . B 24
27. Notice as to load ........... . ... B 24

PART IIIA

SITE FORMATION WORKS

27A. Site formation works... ... ... ... ... ... ... ... ... ... ... ... B 25





Regulation PART IIIB Page

BULK EXCAVATIONS

27B....................Bulk excavation in scheduled area ... ... ... ... ... ... ... ... ... B 25

PART IIIC
GROUND INVESTIGATION

27C......................Ground investigation in scheduled area ... . ... ... ... ... ... B 25

PART IV

FOUNDATIONS

28. Foundations ................................. ... ... ... B -2 6
29. Construction of foundations ............ . ... ... ... ... ... ... ... 13 26
30. Site investigation .................... ... ~ 1 . ... ... ... ... ... B 26
31. Settlement ............................... ... ... ... ... ... - ... B 27
32. Safe bearing capacity ..........-............ ... ... ... ... ... B 27
33. Allowable bearing pressure ............ .. 1 ... ... ... ... ... ... B 27
34. Permissible pressure on concrete......... ... ... ... ... ... 1 ... ... B 29
35. Piling ...................................... ... ... - - ... ... ... B 29
36. Pressure from adjacent ground.......... ... ... ... ... ... 8,11
37. Foolings ..................... ....... ... . 1 . ... ... ... 8,11
38. Caissons .............................. ... ... ... ... ... ... ... 8 32
39. Grouting ................................. B 3-1

PART V

SITES AND FLOORS

40. Covering of sites .......................... ... ... B 3
41. Areas. etc. to be paid................. ... ... ... ... ... B 34
42. Certain floors to be impernicale -.... ... ... ... ... ... ... ... B 34
43. Lowest floor to be above ground level ... ... ... ... ... - ... ... B 3,4
44. Ventilation below wood floors ................. ... ... ... ... ... B 34
45. Construction of wood floors ......-.......... ... ... ... ... ... B 35
46. Skirting 11 . B35

PART VI

WALLS AND PIERS

47. Construction and bonding of walls ......... ... . ... ... ... ... B 35
48 Buildings over 4 storeys or 15 m in height B35
49. Application of regulations ... ... ... ... ... ... ... B 35
50. Rules for measuring height of storeys and height of walls ... ... ... ... ... B 36
51. Rules for measuring lenght of walls B 36
52. Thickness of external walls and party walls of buildings other than public
building or buildings ofthe waterhouse class..,,., ... ... ... ... ... ... ... B 353. Thickness of external and party walls of public buildings and building of the
warehouse class ... - . ... ... ... ... ... ... ... ... ... ... ... B 3.1
54. Thickness of internal load bearing walls ... ... ... ... ... ... ... ... ... B 38





Regulation Page

55. Recesses and openings ... ... ... ... ... ... ... ... ... ... ... ... B 38
56. Loads on walls ... ... ... ... ... ... ... ... ... ... ... ... .. ... B 39
57. Corbelling and overhanging work ... ... ... ... ... ... ... ... ... ... B 39
58. Thickness ofwalls where difference in ground levels ... ... ... ... ... ... B 40
59. Thickness of external walls of certain small buildings ... ... ... ... ... ... B 40
60. Cavity walls... ... ... ... ... ... ... ... ... ... ... ... ...---B 40
61. Glass block walls ... ... ... ... ... ... ... ... ... ... ... ... ... B 41
62. Parapet walls... ... ... ... ... ... ... ... ... ... ... ... ... ... B 41
63. Boundary walls and fences ... ... ... ... ... ... ... ... ... ... ... B 41
64. Definition of slenderness ratio ... ... ... ... .. ... ... ... ... ... ... B 42
65. Maximum compressive stresses in walls or piers of bricks or building blocks ... B 42
66. Maximum compressive stresses in walls and piers of concrete ... ... ... ... B 43
67. Eccentric loads and lateral forces on slender walls ... ... ... ... ... ... B 4 5
68. Panel walls ...... ... ... ... ... ... .... . ... ... ... ... ... B 45
69. Cladding ...... ... ... ... ... ... ... ... ... ... ... ... ... B 46
70. Party walls to he carried up to roof B46
71. Timber not to be built into walls il .. ... ... ... ... ... ... ... ... 846
72. Damp-proof courses ... ... ... ... ... ... ... ... B 47
PART VII

FIREPLACES, FLUES AND CHIMNEYS

73. Fireplaces and stoves to have hearths ... ... ... ... ... ... ... ... B47
74. Fireplace openings ... ... ... ... ... ...------... ... ... B 47
75. Fireplaces to have chimneys an flues ... ... ... ... ... ... ... ... ... B 48
76. Chimney stacks to he carried above roof ... ... ... ... ... ... ... ... B 48
77. Combustible materials in proximity to chimneys ... ... ... ... ... ... B 49
78. Chimney shafts ... .. ... ... ... ... ... .. . ... ... ...---... ... B 49
79. Open cooking slabs to have hoods ... ... ... ... ... ... ... ... ... ... B 51
80. Ceilings over fireplaces to be protected ... ... ... ... ... ... ... ... ... B 51

PART VIII

ROOFS

81. Roofs to be covered ... ... ... ... ... ... ... ... ... ... ... B 51
82. Roofs to be weatherproof ... ... . ... ... ... ... ... ... B 52
83. Accessible roofs to have parapet or railings ... ... ... ... ... ... ... ... B 52
84. Hollow ceilings .. ... ... ... ... ... ... ... ... ... ... ... ... ... 852

PART IX

DUTIES OF REGISTERED STRUCTURAL ENGINEER IN STRUCTURAL
USE OF TIMBER. STEEL AND REINFORCED CONCRETE


85. Steel framed a d reinforced concrete structures ... ... ... ... ... ... ... B 52
PART X

STRUCTURAL USE OF TIMBER

86. Finished sizes of structural timber ... ... ... ... ... ... ... ... ... ... B 53
87. Minimum load on ceiling joists and floor boards ... ... ... ... ... ... ... 853





Regulation Page

88. Maximum permissible stresses in structural timber ... ... ... ... ... ... B 53
89. Maximum permissible stresses for posts and struts - .11 ... ... ... ... B 54
90. Effective length of posts and struts ... ... ... ... ... ... ... ... ... ... B 55
91. Maximum deflexion ... ... ... ... ... ...... ... ... ... ... ... - -B 56
92. Stresses due to imposed load on pitched roof ... ... ... - ... ... ... B 56
93. Combined bending and axial stresses ... ... ... ... ... ... ... ... ... B 56
94. Joints and connexions - ... ... ... ... . ... ... ... ... B 56

PART XI

STRUCTURAL USE OF STEEL

95. Cleaning and protection against corrosion B 56
96. Protection ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... B 57
97. Stresses (steel other than columns and struts) ... .1 . ... ... ... ... . B 57
98. Stresses in columns and struts ... ... ... .. ... ... ... ... ... .. ... B 61
99. Stress due to wind ... ... ... ... ... ... ... ... ... ... ... ... ... B 63
100. Combined stresses . ... ... .. ... ... ... ... ... ... - ... B 63
101. Grillage beams ... ... ... ... ... .. ... ... ... ... ... ... ... ... B 64
102. EfFective length of columns and struts ... ... ... ... ... ... ... ... B 64
103. Ends of columns ... ... .. ... ... - ... ... ... ... ... ... B 65
104. Buses for columns ... ... B 65
105, Joints in columns ... ... ... - ... ... ... ... ... ... B 66
106. Filler floor beams ... ... ... ... ... ... ... ... ... ... B 66
107. Deflexion and span of beams ... ... ... ... ... ... ... ... ... ... B 67
108. Thickness of steel ... ... B 67
109. Bolts - . ... ... ... ... ... ... ... ... ... ... B 68
110. Rivets and riveting ... ... ... ... ... ... - ... ... - ... - . B 68
111. Welding ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... B 69
112. Fabrication and erection ... ... ... ... ... ... ... ... ... ... ... ... B 69
113. Saving... - . ... ... .. ... ... ... ... ... ... ... ... B 70

PART XII

STRUCTURAL USE OF REINFORCED CONCRETE

114. Reinforcement ... ... ... ... ... ... ... ... ... ... ... ... ... ... B 70
115. Minimum cover of reinforcement ... ... ... ... .... B 70
116. Stresses in reinforced concrete ... ... ... ... ... ... ... ... ... ... ... B 71
117. Stresses in reinforcement ... ... ... ... ... ... ... ... ... ... ... ...B72
118. Stresses in reinforced conerete columns ... ... ... ... ... B 73
119. Effective length of columns .............. ... ... ... B 74
120. Stresses due to wind...................... ... ... B 74
121. Longitudinal reinforcement for columns ... ... . ... ... ... ...B 74
122. Transverse or helical reinforcement for columns ... ... . ... ... ... ... B 75
123. Diameter of reinforcements ... ... .. ... ... ... ... ... ... ... ... B 76
124. Spacing of reinforcements ... ... ... ... ... - . 1 . ... ... ... ... B 76
125. Shear reinforcement ... ... ... ... ... ... ... ... ... ... ... ... B 76
126. Stirrups - ... ... ... ... ... ... ... ... ... ... ... B 77





Regulation Page

127........................Reinforcement in solid slabs ... ... ... ... ... ... ... B 77

128 Compression reinforcement ............. --- ... ... ... ... ... B 77

129...............Reinforced concrete walls ... ... ... ... ... ... ... ... ... ... ... B 78
130...............Welding of reinforcement ... ... ... ... ... ... ... ... ... ... ... B 79

131...........Basis of design ............. ... ... ... ... ... ... ... ... ... ... B 79
132...........Stiffness of members .............. ... ... ... ... ... ... ... ... ... B 80
133...........Effective span .............. ... ... ... ... ... ... ... ... ... ... B 81

134...............T-beams and L-beams ..... . ... ... ... ... ... ... ... B 81

135.............Bending moments .............. .... ... ... ... ... ... ... ... . B 82

136........................Beams and slabs spanning in 1 direction ... ... ... ... ... ... ... 882

137. Slabs spanning in 2 directions at right angles with uniformly distributed loads B83

138..........................Distribution of concentrated load on solid slabs ... ... ... ... ... ... B 88

139...............Trimming for openings ...... ... ... ... ... ... ... ... ... ... ... B 88

140.............Resistance to shear .......... ... ... B 88
141.............Bond and anchorage ........ B 89

142...............................Floors and roofs of ribbed and hollow block construction .. ... ... ... B 92

143....................Permissible loads on columns-- ... ... ... ,, --- *** ... ... B 94

144........Footings ............. ......... ... ... ... ... ... ... ... ... B 96

145........................Method of design for flat slab construction ... ... ... ... ... ... ... B 96

146............................Definitions and notation or flat slab construction ... ... ... ... ... B 96

147........................Division of panels in flat slab construction ... ... ... ... --- ... B 97

148....................Minimum thickness of flat slabs ... ... ... ... ... ... ... ... ... B 97

149.................Shearing stresses in flat slabs ... ... ... ... ... ... ... ... ... ... B 97

150............................Columns and column heads in flat slab construction ... ... ... ... ... B 98

151........................Openings in panels in flat slab construction ... ... ... ... ... ... ... B 99

152....................Drops in flat slab/Construction ... ... ... ... ... ... ... ... ... B 100
153....................Reinforcement of flat slabs generally ... ... ... ... ... ... ... ... B 100

154................................Panel with ma r linal beams or walls in flat slab construction . ... ... B 101

155. Design of flat slabs as continuous frames... ... ... ... ... ... ... ... B 101

156. Empirical design of flat slabs B 102

157.................................Maximum permissible stresses in special and designed mixes ... ... ... B 104
158. Increase in maximum permissible steel stresses B 106

159. Stresses in columns of special and designed mixes ... ... ... ... ... ... B 107







160. Stiffness of members with higher steel and concrete stresses ... ... ... ... B 107

161. Load factor method of design ... ... ... ... ... ... ... ... ... ... ... B 107

162. Slender beams and long columns designed by. the load factor method ... ... B 108

163. Simplified formulae for rectangular beam and solid slab sections in load factor

method ... ... ... ... --- ~ .. ... ... ... ... ... ... ... ... ... B 108
164. Simplified formulae for T-beams or L-beams in load factor method ... ... ... B 109


165. Formulae for short columns subject to both direct load and bending in load
factor method ... .... ... ... ... ... B 110

PART XIII

WHARVES, PIERS AND SEA-AALLS

166. Wharves, piers and sea-walls ... ... ... ... ... ...B112





Regulation Page
PART XIV

RETAINING WALLS

167. Materials and design...---... ... ... ... ... ... ... ... ... ... ... B 112
168. Foundations ... ... ... ... ... ... ... ... ... ... ... .. 1 ... ... B 112
169. Brickwork ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... B 112
170. Masonry ... ... ... ... ... ... ... ... ... ... ... ...---... ... B 112
171. Bond courses required ... ... ... ... ... ... ... ... ... ... ... ... B 112
172. Weep holes... ... ... ... ... ... ... ... J ... ... ... ... ... ... B 113
173. Copings and parapets ... ... ... ... ... B 113
174. Surface channels ... ... B H3

PART XV

WELLS

175. Permission from Building Authority to sink or reopen wells ... .. 1 ... ... B 113
176. Wells prohibited in certain places B 114
177, Wells to be of sufficient depth and diameter ... ... ... ... ... ... ... ... B 114
178. Wells to be lined and filter required ... ... ... ... ... ... ... ... B 114
179. Access for cleaning and close-fitting cover required ... ... ... ... ... ... B 114
180. Channels and paving to ground surface adjoining top of wells required ... ... B 115
181. Parapet wall required where water is drawn by a bucket ... ... ... ... ... B 115

PART XVI

FIRE RESISTING CONSTRUCTION

182. Interpretation ...... ... . ... ... ... ... ... ... .. ... ... B 115
183.............Adjacent buildings ... . ... ... ... ... ... ... ... ... ... ...B 115
184. Elements ofconstruction within buildings ... ... ... ... ... ... ... ... B 115
185. Adjoining compartments to he paraled ... ... ... ... ... ... ... ... B 117
186. Staircases ... ... ... ... ... ... ... ... ... ... ... ... ... ... B 117
187. Topmost storeys ... ... . .. ... ... ... ... ... ... B 118
188 Openings in walls separating compartments or enclosing staircases ... ... ... B 118
189. Borrowed lights...---... ... ... ... ... ... ... ... ... ... B 118
190. Basements ... ...---... ... ... ... ... ... ... ... ... ... ... B 118

PART XVII

MISCELLANEOUS

191. Doors for the disabled.. ... ... ... ... ... ... ... ... ... ... ... B 118

First Schedule. Methods for deter ning the resistance to crushing of concrete ... ... B 119
Second Schedule. Design of concrete mixes ... ... ... ... ... ... ... ... ... ... B 122

Third Schedule. Minimum requirements for construction and materials to be capable of
resisting the action of fire for specified periods ... ... ... ... ... B 124






BUILDING (CONSTRUCTION) REGULATIONS

(Cap. 123, section 38)

[7 February 1975.]

PART I

PRELIMINARY

1. These regulations may be cited as the Building (Construc-
tion) Regulations.

2. In these regulations, unless the context otherwise requires-

'B.S.' means the relevant British Standard published by the British
Standards Institution;
in relation to a wall, means the under side of that part of the
wall which immediate rests on the footings or foundation or
other structure by which the wall is carried.,

'bulk excavation' means all excavation except excavation for
ground investigation, public utility trenches, drains, sewers,
piles or caissons;

'caisson' means a foundation structure achieved by sinking a shell
through ground or water for the purpose of placing the founda-
tion at the required depth and shall include deep piers and
bored piles exceeding 900 m in diameter..

'chimney' means a construction enclosing a flue and attached to or
forming part of a building,

-chimney shaft- means a contruction not bonded into a building,
enclosing a vertical flue extending to a height above its topmost
lateral support greater an 6 times its least horizontal dimen-
sion measured at-

(a)the base of the chimney shaft where it is not supported
above the base; or

(b) the level of the topmost lateral support.

'chimney stack' means such part of a chimney (or combination of 2
or more chimneys),as is not within a building;

'cladding' means a structure for the purpose of facing or architec-
tural decoration additional to the external walls of any building;

'C.P.' means the relevant British Standard Code of Practice pub-
lished by the British Standards Institution;

'dead load' means the weight of walls, floors, roofs, partitions and
other permanent construction;





'dividing wall' means a wall which is required to be taken into
account in pursuance of regulation 51 in deeming another wall
to be divided into distinct lengths:

-external wall- means an outer wall of a building not being a party
wall. even though adjoining a wall of another building;

'flue' means a duct through which smoke or other products of
combustion or fumes from any cooking apparatus or stove or
oven. or vitiated air, pass or are intended to pass for the
purpose of reaching the open air,'

'imposed load' means load other than dead load and includes wind
pressure,

'incombustible material- means a material which neither burns nor
gives off inflammable vapours in sufficient quantity to ignite at
a pilot flame when heated in the manner specified in the
appropriate provisions of B.S. 476:1932 and -combustible
material- shall be construed accordingly;

'lateral support- in relation to a wall or pier means support which
resists movement in the direction of the thickness of the wall or
in the direction of the thickness or width of a pier;

'load bearing' in relation to any part of a building (including the
foundation) means aoy such part bearing a load other than that
due to its own weight and to wind pressure on its own surface.

'load factor' means the ratio of ultimate load of a member to its
working load;
'partition wall' means any internal wall not being a dividing wall,
external wall or party wall:

'party wall' means a wall forming part of a building and used or
constructed to used for the separation of adjoining buildings
belonging to different owners or occupied or constructed or
adapted to be occupied by different persons:

'plain concrete' means concrete complying with the provisions of
regulation 19 in which no reinforcement is included for struc-
tural purposes but in which reinforcement may be provided for
the purpose of restraining shrinkage or other movement.

'prestressed concrete' means concrete in which predetermined
stresses are induced to counteract the stresses due'to dead and
imposed loads for the purpose of eliminating or decreasing the
tensile stresses in concrete due to bending and shear,

'public building' means a building used or intended to be used
either ordinarily or occasionally as-

(a)a plade of public worship or for instruction other than a
place so used and being part of a domestic building;

(b) a hospital.





(c)a restaurant having a seating capacity for more than 100
persons; and

(d)a place of public entertainment or assembly to which
persons are admitted by ticket or otherwise,

'reinforced concrete' means concrete not inferior to that designated
Grade 111 in regulation 19 and reinforced by reinforcement
which complies with the provisions of regulation 20;

',safe bearing capacity' means the intensity of the loading due to the
weight and imposed loads of any proposed building works
including earth works (if any) that the ground under a founda-
tion will safely carry without risk of shear failure irrespective of
any consolidation settlement that may result;

-shell lime' means lime formed by burning sea shells or other like
marine calcium deposits;

',storey-height' for the purposes of regulations 64 to 67 means the
height of that part of a walhor pier which is between the level of
one lateral support and the level of the lateral support next
above or (if there is no such lateral support above) the top of
such wall or pier;

'ultimate bearing capacity- means the value of the net loading
intensity in the ground on any horizontal plane at which the
ground fails in shear.

3. All materials used in the construction of any building
shall---

(a)be of a suitable nature and quality for the purposes for
which they are used;

(b) be adequately mixed or prepared; and

(c)be applied,, used or fixed so as adequately to perform the
functions,for which they are designed.

4. The Building Authority may permit in writing subject to
such conditions as he may endorse thereon the use of any type of
material or any method of mixing or preparing materials or of
applying, using or fixing materials which conforms with a British
Standard Specification or a British Standard Code of Practice
prescribing the quality of material or standards of workmanship:

Provided that in the event of more than one such Standard or
Code having been issued, the type of material or method used shall
conform with the latest edition and any published amendments
thereto unless in these regulations a specific edition of Standard or
Code is required to be adopted.

5. Every building shall be so designed and constructed as to
be capable of sustaining safely and transmitting all the dead and
imposed loads without exceeding the appropriate limitations of
permissible stresses.





6. Where load is transmitted through plain concrete, brick-
work or other similar material, the angle of dispersion of the load
through that material shall be taken as not more than 45 with the
direction of the load.

7. No building shall be subjected to load beyond its proper
bearing capacity:

Provided that this regulation shall not apply with respect to any
load which may be required or permitted by the Building Authority
for the purpose of testing.

8. Where demolitions or other building works are carried out
which may affect adversely any adjoining or other building or street.
such building or street shall be provided with adequate support.

PART II

MATERIALS

9. (1) Every brick and building block shall be composed of
hard well-burned clay, natural or cast stone, concrete or other
incombustible material of like hardness and durability and shall
possess resistance to crushing not less than those respectively
specified in Table I.

(2) Cast stone and concrete blocks shall be cured at normal
temperatures until they attain the strengths specified in Table I and
in any case for not less than 4 weeks.


(3) Every brick and building block shall be of such size, shape
and surface as to permit of proper bonding and jointing.

(4) Where bricks and building blocks are formed with cavities.
hollows or perforations-

(a)the volume of such cavities, hollows or perforations shall
not exceed 1/2 the total volume of the brick or building
block;

(b)such cavities, hollows or perforations shall be so disposed
that the aggregate width of solid material measured at
right angles horizontally to the face of such brick or
building block shall be not less than 1 of the width thereof
at any one place;

(c)no wall of any cavity, hollow or perforation shall be less
than 20 m;

(d) such bricks or building blocks shall be so laid as not to
provide harbourage for vermin;

(e)no chase or recess shall be formed in such bricks or
building blocks,





(f) such bricks or building blocks may be used in load bearing
walls only-
(i) in single storey buildings;
(ii) in 2-storey domestic buildings; or
(iii) for enclosing the top storey of a building.

TABLE I

Bricks and building blocks

Description of brick or building block 3

1 2
Resistance to crushing in MPa
of gross horizontal area
Whether solid or
Purpose hollow

External or internal solid 10
(load bearing)
External or internal hollow 5
(load bearing)
External (panel) solid or hollow 3.5
(non-load bearing)
Internal (partition) solid or hollow 1.5
(non-loading bearing)

10. Cement shall be-

(a) ordinary Portland cement in conformity with the appropri-
ate provisions of B.S. 12:Part 2:1971; or
(b) rapid hardening Portland cement in conformity with the
appropriate provisions of B.S. 12:Part 2:1971;or

(c)Portland blast-furnace cement in conformity with the
appropriate provisions of B.S. 146: Part 2:1973; or

(d) any other cement approved by the Building Authority.

11. Stone lime shall consists of-

(a) quicklime formed by burning a natural rock or other
suitable material at such a temperature that it will slake
when brought into contact with water., or

(b)dry hydrated lime in the form of a fine dry powder
produced by treating quicklime so as to produce a dry.
sound product:

Provided that the calcium and magnesium compounds
present in the lime as oxides shall be not less than 70 per
cent by weight.





12. (1) Sand shall-

(a)consist of naturally occurring sand, crushed stone or a
combination of both,

(b) be hard, clean and free from adherent coatings;

(c) contain no appreciable amount of clay balls or pellets;

(d)contain no greater proportion of fine clay, silt or fine dust
(being such clay, silt or dust as will pass through a 25 urn
sieve) than-
(i) 5 per cent by mass in the case of naturally occurring
sand;and
(ii) 10 percent by mass in the case of crushed stone.

(2) Sand shall contain no harmful material in sufficient quan-
tity adversely to affect the hardening strength or durability of the
mortar, plaster or concrete, or, in the case of reinforced concrete,
to attack the reinforcement.

13. Red earth shall consist of decomposed rock containing not
more than 15 per cent of clay. It shall contain no harmful material
in sufficient quantity adversely to affect the hardening strength or
durability of the mortar or plaster.

14. Water shall be clean fresh water free from harmful matter.

15. (1) Cement mortar shall be composed of cement and sand
in the proportion of one volume of cement to not less than 2 nor
more than 4 volumes of sand.

(2) Lime or red earth may be added to such cement mortar in
the proportion of no more than 25 per cent of the cement in volume.

16. Cement-lime mortar shall be composed of cement, sand
and stone lime or shell lime, mixed by volume in the proportions
shown in Table II.

TABLE II

Cement-lime mortar


Note:Not more than 25 per cem of the volume of sand maybe replaced by an equal
volume of red earth.





17. (1) Lime mortar shall be composed of stone lime or shell
lime, sand or red earth mixed by volume in the proportions shown in
Table 111.

(2) Lime mortar with a base of shell lime shall not be used in
the construction of any load bearing wall.

TABLE III

Lime mortar


Note: Not more than 25 per cent of the volume of sand may be replaced by an
equal volume of red earth.

18. (1) Aggregate for plain concrete shall consist of sand.
well-burnt brick, well-burnt tile, well-burnt clinker, stone or any
other material of which the Building Authority may approve. It
shall be so graded as to make a sound concrete.

(2) Aggregate for reinforced concrete shall-

(a) consist of sand and crushed stone;

(b)be hard, strong and durable and reasonably clean and free
from clay, organic or other harmful matter;

(c) being fine aggregate, be of such size that-
(i) at least 90 per cent by mass will pass a 5 mm mesh
screen; and
(ii) not more than 15 per cent by mass will pass a 150
um mesh;

(d) being coarse aggregate, be of such size that-
(i) not more than 10 per cent by mass will pass a 5 mm
mesh screen; and

(ii) at least 95 per cent by mass will pass a mesh of a size
6 mm less than the minimum lateral distance between
reinforcing bars, or 6 mm less than the minimum cover,
whichever is the smaller, or in the case of solid slabs will
pass a 20 mm mesh screen; and

(e) be so graded as to make a dense concrete.





(3) Notwithstanding paragraph (2) but subject to paragraph
(2)(d)(1i). aggregate for reinforced concrete shall conform with the
appropriate provisions of B.S. 881Part 2:1973:

Provided that fine aggregate of grading zone 4 as given in
Table II of B.S. 882:Part 2:1973 may be used only in special and
designed concrete mixes.

19. (1) Concrete shall be composed of aggregate mixed with
cement and water.

(2) The fine aggregate and coarse aggregate shall be measured
separately.

(3) The proportions of cement to aggregate shall be those
specified in Tables IV, V and VI for the appropriate grade of
concrete:

Provided that-

(a)the use of any admixture shall be subject to the approval of
the Building Authority.

(b)where the Buildingg Authority approves the use of a cement
under regulation 10(d) the proportions of cement of aggre-
gate shill be tbose approved by the Building Authority;
and

(c)where the Building Authority is of the opinion that in any
particular case other proportions will produce a suitable
grade of concrete, he may permit such proportions for that
case.

(4) (a) Concrete designated as Grades I-V in column 1 of
Table IV and having the resistance to crushing specified for
such grades in the last column of that Table shall be known
as---Ordinary--- concrete.

(b)Concrete designated as Grades IA-IIIA in column 1 of
Table V , and having the resistance to crushing specified for
such grades in the fast column of that Table shall be known
as 'Quality A- concrete.

(5) The quantity of water used for making concrete shall not
exceed that required to ensure that the concrete is uniformly mixed.
can be readily placed and worked into position. and will make a
sound concrete.

(6) Concretes shall

(a)be deposited before setting has commenced and without
segregation of the materials;

(b)be adequately consolidated by tamping or any other means.
including vibrating, approved by the Building Authority:





(c)remain undisturbed after consolidation until hardened
sufficiently to withstand safely any stresses to which it may
be subjected.. and

(d)be adequately protected from the weather, from premature
drying. or other causes of damage until it has hardened.

(7) Notwithstanding the provisions of paragraph (3) but sub-
ject to the provisions of regulations 157 to 165 and the First and
Second Schedules, concrete mixes may be designed to possess a
resistance to crushing within the ranges specified/in Table VI subject
to the mix limitations in that Table beinQ complied with and such
mixes shall be known as special mixes or designed mixes.

(8) In the application of Tables IV and V-

(a) (i) cement shall be measured by weight,
(ii) aggregate may be measured by weight
(iii) the weight required shall be determined from the
volume given in the Tables and the mass per cubic metre of
the aggregate; and
(iv) the proportions given in the tables are for dry
aggregates and wehter the aggregates are moist due allow-
ance must be made for bulking; and

(b) (i) concrete shall satisfy the requirement for resistance
to crushing at 28 days after mixing:
(ii) the resistance to crushing at 7 days after mixing
may be used as a control but a sufficient number of tests at
28 days after mixing shall be made to confirm that the gain
in strength between 7 and 28 days is satisfactory; and
(iii) the respective ratio of resistances to crushing at 7
and 28 days shown in the Tables are appropriate for
ordinary Portland cement and where rapid hardening
Portland cement alters the ratio it is to be adjusted
accordingly.

(9) In the application of Table VI--

(a) the weights of aggregate given in the Table are based on
the density of crushed granite, and should be adjusted
accordingly for aggregate with a density different from
crushed granite, and

(b) the ratio of the resistance to crushing within 7 days after
mixing to the resistance to crushing within 28 days after
mixing shall be taken as 1:1.3 for intermediate resistances
within the limits specified in Table VI.

(10) High alumina cement concrete shall not be used in general
building works except with the written approval of the Building
Authority.





TABLE IV

Ordinary concrete: grades I to V


* Sum of oiumqs of line and coarse aggregates measured ~epdrutely.

TABLE V

Quality A concrete: grades IA to IIIA

* Sum of volumes of fine and coarse aggregates measured separately





TABLE VI

Special and design concrete mixes


20. Reinforcement for concrete shall be-

(a) hot rolled steel bars in conformity with the appropriate
provisions of B.S. 4449:1969;

(b)hard drawn mild steel wire in conformity with the appro-
priate provisions of B.S. 4482:1969;

(c) cold worked steel bars in conformity with the appropriate
provisions of B. S. 4461:1969,

(d)steel fabric in conformity with the provisions of B.S.
4483:1969;

(e)such othe reinforcement as the Building Authority may
approve as being suitable, having regard to the particular
circumstances of the case.

21. All structural and rivet steel used in building shall, before
fabrication-

(a) comply with either-
(i) Grade 43, B.S. 4360 relating to mild steel for general
structural purposes; or
(ii) Grade 50, B.S. 4360 relating to high yield stress
(welding quality) structural steel,

whichever is appropriate; or

(b)be such structural and rivet steel as the Building Authority
may approve.







22. (1) Structural timber shall be---
(a) (i) Oregon Douglas Fir (Pseutlot.~ug(i iax~folia (Poiret)
Britton);
(ii) Longleaf Pine or Pitch Pine (Pinus Palustris Miller);
(Iii) Shortleaf Pine or Pitch Pine (Pinus echinala Mil-
ler), or
(M Keruing (Dipterocarpus Spp.),
which for the purpose of these regulations shall be known
as Class A timber;
(b) (i) Canadian Spruce (Picea glauca (Moench) Voss);
(ii) European Larch (Larix decidua Miller), Red Pine
(Pinus resinosa Aiton);
(iii) Western Hemlock (T.,;ug(t hetep.opl~i,Iia (Refines-
que) Sargent), Common.Spruce or White Fir (Picea abies
(Litinacus) Karsten)., or
(iv) Red Meranti/Red Seraya/Red Luaun (Shorea Spp.),
which for the purpose of these regulations shall be known
as Class B timber, or

(c)such other timber as the Building Authority may approve
as beihg suitable, having regard to the particular circum-
stances of the case.

(2) The provisions of paragraphs A2-A17 inclusive of Appen-
dix A to C.P. A 112:Part 2:1971 shall apply to all timber to be used for
structural purposes and such timber shall comply with the minimum
requirements for 50 grade timber as required by Appendix A to C.P.
112:Part 2:1971.
(3) Structural timber (other than tiling battens) shall be
properly seasoned and when tested by the methods described in
Appendix A to C.P. 112: Part 2:1971 the moisture content shall
not exceed 22 per cent.

23. Materials for damp-proofing shall consist of---
(a) sheet lead or sheet copper;

(b) asphalt,

(c) self finished bitumen impregnated felt laid in bitumen,

(d)a core of sheet lead and bituminized hessian cloth between
2 layers or coats of bitumen surfaced with talc or other
suitable material;

(e)a core of sheet lead between 2 layers of bituminized felt
fibre coated with bitumen and surfaced with tale or other
suitable material; or

(f) any other suitable material or combination of materials.
which the Building Authority may approve as being dur-
able, impervious to moisture and in all other respects
suitable for their purpose. having regard to the particular
circumstances of the case.





PART III

LOADS

24. (1) Every building, including its foundations, shall be
designed to the satisfaction of the Building Authority to resist the
combined effects, as well as the separate effects, of dead and imposed
loads and wind loads on walls and roofs, including internal wind
pressures, for winds from any direction.

(2) A building shall be deemed to be designed in accordance
with paragraph (1) in respect of wind load if its design complies with
the Code of'Practice on Wind Effects published from time to time by
the Building Authority.

25. (1) In calculating dead load, the unit weights of the
materials shall be deemed to be-

(a)those specified in B.S. 648:1964 in the case of material
therein mentioned, and

(b) in the case of any otheV materials. such unit weights as may
be ascertained to the satisfaction of the Building Authority.

(2) The dead load of any partitions whereof the positions are
not definitely located in the design of the building, shall be deemed
to be a uniformly distributed load/m2 of the floor on which the
partitions are to be created of 30 per cent of the estimated dead
weight per metre run of those partitions but no less than 1 kPa/m2 if
that floor or part of a floor is used for office purposes.

(3) In all cases the imposed loads to be provided for shall be
ascertained to the satisfaction of the Building Authority but. subject
to the provisions of this regulation-

(a)the minimum imposed loads (not including induced wind
loads) for the floors, roofs, stairs and landings and corri-
dors and cantilever steps of the types specified in Table VII
and for slabs forming part of, and for beams supporting
such floors, roofs, stairs and landings and corridors and
cantilever steps, shall be-
(i) the loads specified in column 3 of Table VII; or
(ii) the loads specified in column 4 or 5, as the case may
be, of Table VII,

whichever shall be the heavier;

(b)for the purpose of ascertaining the reactions to be allowed
for in calculating the loads on columns. piers, walls or
foundations, the minimum imposed loads (not including
induced loads from wind effects) shall be either-
(i) the loads specified in column 3 of Table VII, or
(ii) as ascertained to the satisfaction of the Building
Authority,

whichever shall be the heavier; and





(c)the imposed loads to be provided for types of floors, roofs,
stairs and landings and corridors and cantilever steps not
mentioned in Table VII shall be ascertained to the satisfac-
tion of the Building Authority.

TABLE VII

Mininium imposed loads (not including induced wind loads)






1 2 3 4 5






1 2 3 4 5


Note: *Specified loading is applied vertically.

(4)(a) In calculating the total imposed load (not including
induced wind loads) on any column, pier, wall or founda-
tion, the minimum imposed loads for every floor carried
thereby may be deemed to be subject to the reductions
specified in Table VIII:

Provided that, in factories and workshops whereof the
minimum imposed load is more than 7.5 kPa, or is more
than 6.0 kPa but not more than 7.5 kPa, the total imposed
load shall be not less than that obtained if all the floors had
been designed for an imposed load of 7.5 kPa or 6.0 kPa
respectively without the reductions specified in Table VIII.











TABLE VIII

Reductions of minimum imposed loads

1 2

Number of floors carried by Percentage reduction of minimum
member under consideration imposed load on all floors above the
member under consideration
0
2 10
3 20
4 30
5 or more 40

(b)Where a single span of beam supports not less than 45 M2
of floor at any one level, the minimum imposed load (not
including induced wind load), for the purpose only of
determining the design of the beam, may be deemed to be
subject to a reduction of 5 per cent for each complete 45 m'
of that floor so supported but not more than 20 per cent in
all.
(c) The reduction specified in sub-paragraph (a) or (b), which-
ever is the greater, may be taken into account in calculating
the total load on ady column, pier, wall or foundation.

(d)The reductions spe'cified in sub-paragraphs (a), (b) and (c)
shall not apply with respect to-
(i) the floors of factories and workshops whereof the
minimum imposed load per m2 is 6 kN or less;
(ii) the floors of warehouses, of garages, and floors used
for storage purposes; or
(iii) indued wind load.

(5) Parapets, handrails and balustrades, together with the
connexions and members which give them immediate structural
support, shall be, designed for the following minimum horizontal
static loads (which shall be assumed to act at handrail or coping
level) or for wind efFects (where applicable)-

(a)stairways, landings and balconies for domestic buildings in
single occupancy---0.35 kN/m;

(b)balustrades, parapets, handrails and barriers in places of
assembly or in garages-2.2 kN/m;

(c) all other stairways, landings and balconies and all para-
pets, handrails and balustrades to roofs and retaining
walls-0.75 kN/m.

(6) No building or part of a building shall be deemed to
comply with paragraph (5) with respect to any moving load or loads
from machinery inducing vibration unless adequate provision for all
dynamic eftets has been made to the satisfaction of the Building
Authority.





26. (1) The test load for any structure or part of a structure,
excepting for piles and foundations, shall be such that the total load
during the test includes the full dead load Plus 1 1/4 times the imposed
load (not including induced wind load) for which that structure or
that part thereof has or should have been designed. This load shall
be maintained for a period of 24 hours before removal.

(2) During the test adequate struts strong enough to take the
whole of the dead load and test load shall be placed in position
leaving a gap under the members to be tested. The test load shall not
be applied to a reinforced concrete structure until at least 28 days
after the date of concreting.

(3) The structure or that part thereof under test shall be
deemed to be satisfactory if all the following conditions are met
within their limits-

(a)no structural defects, signs of weakness or faulty construc-
tion can be observed; and

(b) the maximum deflexion during the test shall not exceed
1/360 of the span 1/180 of the span for cantilevered members);
and

(c) within 4 er removal of the applied test load, the
recovery of deformation shall be not less than-
i) in the case of a reinforced concrete or steel framed
structure, 75 per cent; and
(ii) in the case of a timber structure, 50 per cent,

of the maximum deflexion during the test.

(4) The Building Authority may require a re-test of a structure
or part of a structure to be carried out with the same loading, and
conditions where the recovery is-

(a) in the case of a reinforced concrete or steel framed struc-
ture, less than 75 per cent but not less than 50 per cent; or
(b) in the case of a timber structure, less than 50 per cent but
not less than 40 per cent.

(5) If on re-test of a structure or part of a structure under
paragraph (4) he recovery is at least-

(a)in th case of a reinforced concrete or steel framed struc-
ture, 75 per cent; or
(b) in th case of a timber structure, 50 per cent,

of the maxim m deflexion during the re-test, the structure or part
shall be deemed to be satisfactory.

27. (1) In every storey of every building with a designed
imposed load (not including wind load) of 5 kPa and over. there
shall be exhibited by the owner, at each staircase or at some other
appropriate place, permanently and conspicuously, a notice in





English and Chinese incised or embossed, of metal, plastic or other
suitable material, in letters and figures not less than 15 mm high,
stating the imposed load for which the floor has been designed, in
the following form-

BUILDINGS ORDINANCE

(Chapter 123)

NOTICE

The imposed load on this floor is not to exceed
........................... kilograms per square metre.

(2) Where floors of different room or different parts of floors
have been designed for difFerent imposed loads, a notice in the form
in paragraph (1) shall be suitably displayed in each room or on each
part of the floor, as the case may be, indicating the variations.

PART IIIA

SITE FORMAION WORKS

27A. (1) Site formation works shall be designed and con-
structed so that during Construction and thereafter there is an
adequate margin of safety of the works and the remainder of the site.

(2) The carrying out site formation works shall not render
inadequate the margin of safety of, or cause damage to, any
building, structure or land.

PART IIIB

BULK EXCAVATION

27B. Bulk excavation in the scheduled area shall not be carried
out below levels to be determined by the Building Authority.

PART IIIC

GROUND INVESTIGATION

27C. All groand investigation in the scheduled areas shall be
designed and carried out to the satisfaction of the Building Authority.





PART IV

FoUNDATIONS

28. The foundations of every building shall be designed and
constructed so as to be capable of sustaining and transmitting safely
all the dead and imposed loads to the ground without impairing the
stability of that or of any other building, street, hillside or slope,
nullah or service.

29. Foundations shall be-

(a) constructed of plain or reinforced concrete; and

(b) at a depth below the surface of the ground sufficient to-
(i) secure adequate bearing capacity of the ground;
(ii) avoid intederence with drains, nullahs, sewers or
other services in,ddjacent streets, roads or lanes;
(iii) avoid overloading the foundations of adjacent
buildings or the ground supporting such foundations; and
(iv) avoid creating unstable conditions in hillsides or
slopes;

(e)of such thinkness, not being less than 150 mm. and of such
width as ay be necessary to comply with the provisions of
regulations 5 and 6:

Provided that where the foundation rests on sound
hard rock the thickness of concrete need be no more than is
necessary to provide a suitable level surface on which to
construct the building. and

(d) symmertrically under the centre of action of the load:
provided that where the foundation is subjected to
bending moment or eccentric loading, it shall be so
designed, as to comply with regulations 5 and 33.

30. (1) Where foundations are proposed to be constructed an
investigation of the site shall be undertaken to establish, to the
satisfaction if the Building Authority, the type and character of the
ground on which the foundations are to be placed.

(2) Where the initial investigation does not established beyond
doubt that the ground is in all respects suitable for the purpose of
supporting the foundations without the risk of undue settlement
instability, further tests must be undertaken appropriate to the
ground conditions and the size and complexity of the building works
and to the satisfaction of the Building Authority.

(3) Soil tests carried out under paragraph (2) shall be con-
ducted in accordance with the relevant provisions of C.P.: 2001
(1957), Site Investigation.

(4) In all cases the data obtained from adjoining sites may be
used in support of the investigation undertaken.








31. (1) In the design of foundations, consideration shall be
given to-
(a) the probable differential settlement of the building; and
(b) the probable total settlement of the building.
(2) Where appreciable variations in ground conditions occur
on a site on which a new building or an extension to an existing
building is proposed to be erected special consideration shall be
given to probable differential settlement and, if the Building
Authority so requires, calculations of the estimated settlements shall
be provided.
(3) The estimated ditferential settlement shall in no case induce
an estimated angular distortion in excess of 1/300 in any part of the
proposed structure unless the Building Authority is satisfied that in
the special circumstances of the case an estimated angular distortion
in excess of 1/300 is acceptable.


32. (1) The safe bearing capacity of the ground shall have a
factor of safety of not less than 3 on the ultimate bearing capacity.
(2) Unless adequate tests are carried out to justify higher
values the safe bearing capacity adopted shall not exceed that
specified in Table IX for the appropriate type of ground.

33. (1) The pressure on the ground under any foundation
shall not exceed the allowable bearing pressure which shall be the
safe bearing capacity or such lesser value as may be necessary for the
control of settlement or for the safety of adjacent cuttings or slopes,
to the satisfaction of the Building Authority.

(2) Where it is proposed to exceed the values in Table IX, the
allowable bearing pressure for rock-

(a)shall be determined with due regard to all the circum-
stances, including the depth of foundations. the jointing of
the rock and the spacing, dip, thickness and degree of
weathering of the joints; and
(b)shall nof exceed the permissible bearing pressure of the
material of the foundation.
(3) For decomposed granite and decomposed volcanics where
approved tests show that the safe bearing capacity exceeds the values
specified in Table IX, the allowable bearing pressure for shallow
foundations shall not exceed 2 times the value specified in Table IX
or such lesser value as may be required under paragraph (1).
(4) For cohesive soils where approved tests show that the safe
bearing capacity exceeds the values specified in Table IX, the
allowable bearing pressure shall not exceed 1 1/2 times the value

specified in the Table IX or such lesser value as may be required
under paragraph (1).
(5) For non-cohesive soils-
(a)whenever there is a risk of the ground water level rising to
a depth below the base of the foundation of less than the





width of that foundation. the allowable bearing pressure
shall not exceed the submerged bearing capacity or such
lesser value as may be required under paragraph (1).
(b)where the foundation is less than 1 metre in width, the
allowable bearing pressure shall not exceed the safe bear-
ing capacity multiplied by the actual width of the founda-
tion measured as a decimal fraction of a metre or such
lesser value as may be required under paragraph (1).
(c)the allowable, bearine,pressure may be increased by 5 per
cent for each 0.3 m of depth below the lowest ground
surface adjacent to the foundation:
Provided that it shall not exceed 2 times the safe
bearing capacily specified in Table IX or such lesser value
as may be required under paragraph (1).
(6) The allowable bearing pressure used in the design of
foundations for resisting the combined effect of dead and imposed
loads may be increased by not more than 25 per cent where such
increase is solely due to wind loads.

TABLE IX

Safe bearing capacities of ground under foundations







Note: In the above table, the terms used shall be deemed to have the following
meanings-
compact - a soil which requires the use of a pick for removal;
loose - a soil which is readily removahie by shovelling only:
dry - that the ground-water level is at a depth of not less than 1 m
or the width of the foundation, whichever is the greater. below
the base of the foundation:
core
recovery
(rock) - the actual length of the core of rock. taken by means of rotary
drills fitted with a coring bit. expressed in percentage of ever~
1.5 m interval of depth the coring is advanced into the rock.

34. The pressure on plain reinforced concrete in founda-
tions shall not exceed those specified in Table X.

TABLE X

Pressure on concrete or reinforced concrete foundations

1 2

Designation as specified in regulation 19 Maximum pressure in kPa
Grade IA 7800
IIA 6500
IIIA 5300
Grade I 5400
II 4700
III 4200
IV 2 100
v 1 600

35. (1) All piling used in connexion with the foundations of
any building shall, to the satisfaction of the Building Authority, be
of adequate load bearing capacity and of an approved type and each
pile shall-

(a)be of material of such quality as to be durable and strong
enough to carry its load without exceeding the appropriate
limitations of permissible stresses and, where plain or
reinforced concrete piles are used. the average compressive
stress on the nominal cross sectional area shall not exceed 5
MPa;

(b)comply with regulation 5 and be designed so as to be
capable of sustaining the working load with a safety factor
appropriate to the type of pile and the method of design
adopted;





(c)be driven or constructed, in accordance with the design of
the foundation and type of pile, to the satisfaction of the
Building Authority and, in the case of driven piles. be
driven in such a manner so as not to damage the material
of the pile or any adjacent piles;

(d)be spaced from adjacent piles at not less than the perimeter
of the pile or 1 m, measuring in each case from centre to
centre, whichever is the greater:

Provided that-
(i) in the case of piles bearing on rock, the spacings may
be reduced to not less than 750 mm or 2 times the least
width of the pile, whichever is the greater; and
(ii) where any pile has been placed incorrectly, any
displacement of the pile exceeding 75 mm in plan from
the designed position shall be taken into account in the
foundation design;

(e)in the case of precast reinforced concrete piles. be designed
and constructed so that the handling stresses do not
exceed the permissible stress in bending for concrete and
reinforcement specified in Table XXVII and XXIX respec-
tively ar so that the driving stresses do not exceed 2 times
the permissible stress in direct compression specified in
Table XXVII,

(f) if of timber, be---
(i) stripped of bark and treated with an approved
preservative process. and
(ii) after driving and before the capping is placed, be
cut to sound wood at the topend so that the cut ofrlevel is
below the probable permanent ground water level.

(g)be capped with plain or reinforced concrete of quality not
inferior to that designated Grade III in regulation 19. and

(h)be adequately restrained against lateral movement at the
top of the pile.

(2) Piled foundations shall be designed and constructed so as
to carry safely all dead and imposed loads on the foundations and
any lateral loading to which the foundations may be subjected.

(3) Where 5 or more piles are placed in such proximity that the
capacity of the piles to sustain loading may be affected by other piles
a pile group shall be deemed to exist and the allowable load on any
group of piles shall not -
(a)exceed the sum of the safe bearing capacities of the piles in
the group multiplied by a group reduction factor of 0.85:

Provided that---
(i) in special circumstances and having regard to the
nature of the ground and the size of the group. the group
reduction factor may be increased with the approval of





the Building Authority, and the Building Authority may
require the group reduction factor to be decreased;
(ii) no group reduction factor shall be applied where the
piles bear on rock of category 1(a), (b) or (c) of Table IX; or
(b)cause the average vertical pressures in the ground pene-
trated by, or underlying the piles, to exceed the allowable
bearing pressures of such ground.
(4)(a) Where piles are driven through subsiding fills or other
subsiding strata and derive support from underlying firmer
materials, consideration shall be given to the downward
frictional forces which may be imposed on the piles by the
subsiding upper strata, and the bearing capacity of each
pile as determined by test or calculated by formula shall
be reduced by the amount of the total downward frictional
force.
(b)For the purposes of this paragraph, the total downward
frictional force may be estimated as the cohesion of
remoulded specimens of the soils multiplied by the surface
area of the pile or the full weight of the ground between
and around the piles in the subsiding strata. whichever is
the lesser.
(5) Where any doubt exists as to the capacity of any pile to
sustain adequately and without undue settlement the load for which
it has been designed the pile all be tested by means of the
imposition of a test load, which load shall be 2 times the load for
which the pile was designed and which shall be maintained for 72
hours and if the total settlement recorded exceeds 15 mm the pile
shall be deemed to be unsatisfactory:
Provided that in any partilcular case the Building Authority may
direct the pile to be tested by any other method to the satisfaction
of the Building Authority, in which case the standard of acceptance
shall be determined to the satisfaction of the Building Authority.
(6) The authorized person or registered structural engineer
shall keep or cause to be kept accurate records of materials and
principal dimensions of each pile and other data relevant to the
particular type of pile used and shall submit 2 copies of such records
to the Building Authority.

36. Where the ground adjacent to any building exerts pressure
upon or causes the application of load to any part of that building.
such building shall be constructed so as to be capable of sustaining
safely and transmitting that pressure or load without exceeding the
appropriate limitations of permissible stresses.

37. Where footings are required to spread loads from walls to
fbundations, the bricks or building blocks below the base of such walls
shall increase downwards by regular offsets not exceeding 1/2 the thick-
ness of the brick or building block on 1 or both sides of such walls.
Such bricks or building blocks shall, where possible, be laid as headers.





38. (1) All caissons shall be constructed of plain or reinforced
concrete not inferior to that designated as Grade IIIA in regula-
tion 19.

(2) Where underground water is encountered during concret-
ing the permissible unit compressive stress under the maximum load
from the superstructure, and all other loads, including negative
frictional forces, shall not exceed 80 per cent of the permissible direct
compressive stresses of concrete as specified in regulation 116 or 157.

(3) Where dewatering is to be undertaken the procedure for
carrying out this operation and any precautionary measures to
avoid settlement of any adjoining buildings, streets or land shall be
to the satisfaction of the Building Authority.

(4) Excavation for caissons shall be carried out with due
precautions to prevent the migration of subsoil.

(5) Where any doubt exists as to the capacity of any caisson to
sustain, adequately and without undue settlement, the load for
which it has been designed the caisson shall be tested-

(a) by means of core drilling of the completed in-situ concrete,
in which case
(i) the core drilling shall be taken through the full depth
of the caisson;
(ii) the core drilling shall be carried down to not less
than 600 mm into the ground upon which the caisson is
founded.
(iii) the completed core so taken shall be properly
marked and arranged in order for inspection on site by
representatives of the Building Authority; and
(iv) the necessary crushing tests shall be carried out by
an independent testing authority; or

(b) by any other method to the satisfaction of the Building
Authority. in which case, the Building Authority shall
determine the standard of acceptance to be adopted.

(6) The authorized person or registered structural engineer
shall keep or use to be kept accurate records of-

(a)materials used in, and principal dimensions of, each cais-
son constructed;

(b) soil layers excavated; and

(e)all tests carried out on the bearing strata or the concrete
laid,

and shall submit 2 copies of such records to the Building Authority.

39. (1) Where improvement of ground bearing capacity under
the foundation is to be achieved by grouting the ground under the
foundation with cement or other mixtures, adequate proof of the
suitability of the method and materials to be used shall be given to
the satisfaction of the Building Authority.






(2) Where grouting treatment has been carried out, adequate
tests of the treated ground, to the satisfaction of the Building
Authority, shall be made.

(3) Where the grout or the pressure from the grout may affect
adjoining or nearby buildings, drainage, nullahs, sewers, streets,
slopes or hillsides adequate precautionary measures. to the satisfac-
tion of the Building Authority, shall be taken.

PART V

SITES AND FLOORS

40. (1) The ground surface within the external walls of every
building shall be covered with a layer of concrete, not inferior to that
designated Grade V concrete in regulation 19, finished smooth on
the upper surface. Such concrete shall have a thickness of-

(a)not less than 150 mm of Grade V concrete where the
concrete is laid on ground;

(b) not less than 100 mm where it is-

(i) not inferior to Grade V concrete and is laid on a
consolidated bed consisting of clinker, broken bricks or
other similar materials not less than 75 mm thick; or
(ii) not inferior to Grade III concrete; or
(iii) reinforced to comply with regulation 5.

(2) Paragraph (1) shall not apply to any building which is-

(a) to be used solely~'
(i) as a foundry or blacksmith's shop;
(ii) for the milling or storage of timber;
(iii) for the storage of acids and chemicals which are
injurious to concrete;

(b) of 1 storey-
(i) open on 2 or more sides; or
(ii) intended to be used solely for the storage of builder's
materials or plant; or
(iii) intended to be used solely as a greenhouse, or tool
shed, and does not communicate by any door, window or
other opening with any building to which paragraph (1)
applies.

(3) Where in any part of a building the layer of concrete
required by paragraph (1) is also a floor of the building, that layer
shall be constructed of concrete not inferior to Grade Ill, not less
than 100 mm thick, and laid on a consolidated bed not less than 75
mm thick constructed of clinker, broken bricks or other similar
materials.





(4) Where in any part of a building the floor next above the
ground is constructed of plain or reinforced concrete. constructed so
as to leave between it and the ground an air space, ventilated in
accordance with paragraph (5) and enclosed so as to prevent its use
for any other purpose. such floor may be deemed to be the layer of
concrete required by paragraph (1).

(5)(a) An enclosed space under a floor shall be ventilated
on at least 2 sides with air-bricks or otherwise, having an
open area of not less than the equivalent of 4 000 mm',,m
of external wall. No single opening in any such air-brick
or ventilator shall exceed 5 mm in its least dimension.

(b)Where the flow of air may be obstructed in places by solid
construction, ducts of a total area equal to not less than 2
times the total area of the opening in the air-bricks or other
ventilator in the external walls shall be formed in such solid
construction.

41. (1) The ground surface of every area, back yard or
alleyway of every building (unless exempted as a garden) shall be
covered with-

(a)a layer of concrete not less than 100 mm thick and not
inferior to Grade V.

(b) stone or brick paying bedded and jointed in cement mortar;

(c) a layer of bituminous macadam 75 mm thick finished
mooth with a stopping of fine bituminous macadam 25
mm thick; or

(d)a layer of such other impervious material as the Building
Authority may approve.

(2) Such surface covering shall be laid to fall at a gradient of
not less than 1 in 80 to a gulley trap or drainage channels connected
to a surface water drain.

42. The floor of every room to which a water supply is
provided shall be constructed of concrete or such other impermeable
material as the Building Authority may approve.

43. The level of the floor next above the ground of every
building shall be not less than 150 mm above the level of the surface
of the external ground, paving or oversite concrete at the entrance to
that floor.

44. (1) Where in any part of a building the floor next above
the ground is constructed of wood, it shall be so constructed as to
leave an air-space not less than 225 mm deep between the level of the
underside of the joists and the level of the upper surface of the layer
of concrete required by regulation 40(1) and that space shall be so
ventilated as to comply with the requirements of regulation 40(5).





(2) The provisions of paragraph (1) shall not apply where a
continuous damp-proof membrance complying with the require-
ments of regulation 23 is provided between the concrete and the
floor.

45. (1) Every wood floor shall be constructed of tongued and
grooved boards, strips or blocks and shall be-

(a)where of boards or strips, nailed or otherwise securely fixed
to floor joists; or

(b)where of blocks, fixed to a screeded concrete sub-floor with
asphaltic bitumen or coal tar or other adhesive as the
Building Authority may approve.
(2) Every wood block floor bedded on concrete in contact with
the ground shall be provided with a continuous damp-proof layer to
protect the timber against rising damp, and such damp-proof layer
shall not be inferior to a layer of hot bituminous adhesive of
sufficient thickness to prevent the wood from coming into contact
with the concrete.

46. Every skirting shall be solidly bedded against the wall to
which it is attached.

PART VI

WALLS AND PIERS
47. The walls of all buildings shall be constructed of-

(a)bricks or building blocks bonded and solidly put together
with mortar;

(b) concrete not inferior to Grade V;

(e) reinforced concrete; or

(d)any of the foregoing materials in combination with a
framework of steel or reinforced concrete.

48. Buildings which exceed 4 storeys or 15 m in height shall be
constructed-

(a) with a frame work of steel or reinforced concrete;

(b) with load bearing walls of reinforced concrete;

(e) with a combination of (a) and (b); or

(d)by any other method of construction approved by the
Building Authority.

49. (1) Except where paragraph (2) applies, walls constructed
of bricks, building blocks or plain concrete other than panel walls,
shall comply with the provisions of-





(a) regulations 71 and 72; and

(b) (i) regulations 50 to 63; or
(ii) regulations 64 to 67.

(2) In the case of a building where the imposed floor load
exceeds 7.5 kPa, the load bearing walls shall be designed and
constructed in accordance with regulation 129.


50. (1) For the purposes of regulations 52 and 53, the height
of the lowest or only storey shall be measured from the base of the
wall, and the height of any other storey shall be measured from the
level of the underside of the floor structure of the storey to the level
of the underside of the floor structure next above it or, if there is no
such storey, then to the highest part of the wall or, in a storey
comprising a gable to 1/2 the height of the gable.


(2) The height of a party wall comprising a gable shall be
measured from its base to the base of the gable; the height of any
other wall comprising a gable shall be measured from its base to 1.
the height of the gable; and the height of any wall not comprising a
gable shall be measured from its base to its highest part excluding
any parapet which does not exceed 1 200 min in height.


51. (1) For the purposes of regulations 52 and 53, walls shall
be deemed to be divided into distinct lengths by piers, buttresses.
chimneys or dividing walls. Such piers, buttresses, chimneys or
dividing walls shall be bonded into the walls, and-

(a) in the case of a pier or buttress shall-
(i) extend upwards from the base of the wall to the top
of the wall;
(ii)be, at any height, not less in thickness (measured so
a include the wall) than 3 times the thickness of the
wall; and
(iii) be not less in breadth than 2 times the thickness of
the wall;

(b)in th case of a chimney shall have a horizontal sectional
area excluding any fireplace opening or flue, of not less
than the area required for a pier or buttress and an overall
thickness of not less than 3 times the thickness of the wall it
is deemed to divide; and

(c)in the case of a dividing wall shall, if an internal load
bearing wall, comply with the requirements of regulation
54(1) and in any case be of a thickness of at least 1/2 of that
prescribed by regulation 52 or 53 in respect of the wall
which it is deemed to divide and shall have a length
measured at right angles to the buttressed wall equal to not
less than 1/6 of its height.





(2) All measurements of length of walls shall be made from the
centres of the return walls, dividing walls, piers. buttresses or
chimneys.

52. Except as provided in regulations 60 and 68 every external
and every party wall built of bricks or building blocks in a building
other than a public building or a building of the warehouse class
shall be-

(a) of not less thickness than that specified in Table XI;

(b)built in cement mortar or cement-lime mortar containing
not more than 6 volumes of sand to 1 volume of cement.

TABLE XI

Thickness of external and party walls of building other than public buildings or
buildings of the warehouses class


53. (1) Except as provided in regulation 68 every external and
every party wall built of bricks or building blocks in a public
building or a butIding of the warehouse class where the imposed
floor load does not exceed 7.5 kPa shall-

(a)be built in cement mortar or cement-lime mortar containing
not more than 6 volumes of sand to 1 volume of cement;





(b)have a thickness at the top and for 5 m below the top of not
less than 340 mm:

Provided that it may be not less than 225 mm for-
(i) a wall having 1 storey height not exceeding 3.5 m;
(ii) the topmost storey height of a wall where that wall
does not exceed 7 m in height.

(2) Every such wall being of the height and length specified in
Table XII shall have a thickness at the base not less than that
specified in that Table.

(3) The thickness of the intermediate parts of such wall
between the base and 5 m below the top shall be of not less thickness
than that obtained if the wall were to be built solid throughout the
space between straight lines drawn each side of the wall and
joining the thickness at the base to the thickness at 5 m below the
top.

(4) Notwithstanding paragraph (1)(b), offisets shall not be
made in a wall between the base and the top thereof, except at the
level of lateral supports.

TABLE XII

Thickness of external and party walls of public buildings
and buildings of the warehouse class

54. (1) Every internal load bearing wall built of bricks or
building block (not being a party wall) shall have a thickness not
less than 1/2 that required under regulation 52 or 53, as the case may
be, for an external or party wall of the same height but 2 times the
length, and in any case not less than 225 mm.

(2) A non load-bearing partition wall, adequately restrained
laterally on all 4 edges may be of a thickness such that when 3 times
its height is added to its length the total does not exceed 200 times its
thickness.

55.(1) (a) Notwithstanding the provisions of regulations 52,
53 and 54(1), openings and recesses may be formed in walls
to which the provisions of such regulations apply.





(h)No such recess shall reduce the width of any wall to less
than 225 mm.

(c)The aggregate width of all recesses and openings formed at
any 1 level shall not exceed 2/3 the length of the wall at that
level.

(d)Where the wall is a buttressing wall, every recess or opening
at any level shall be at a distance from the buttressed wall
of not less than ' the height of the buttressing wall.

(2) An arch or lintel sufficient to support the superstructure
shall be built of incombustible material over every recess or opening
in any wall.

(3)(a) Openings may be formed in party walls other than
those separating parts of the building in different owner-
ship.

(b) Such openings shall be fitted with self-closing doors in
frames, the whole so constructed as to be fire resisting for
at least 1/2 hour.

(c)In any row of houses or terrac exceeding 35 m in length or
consisting of more than 6 houses or tenements, party walls
without openings shall be provid at a distance apart not
exceeding 35 m, or 6 houses or tenements, whichever is the
less.

(d) Where opening in party walls are closed, bricks or solid
building blocks not less 225 mm in thickness or
reinforced concrete not less than 100 mm in thickness shall
be used.

(4) For the purpose of this regulation. the expression---recess-
shall include any chase or other reduction in the required thickness
of a wall.

56. (1) A wall shall not be subject to loads other than distri-
buted loads:
Provided that any wall may be subject to any concentrated load
which is transmitted to that wall by a beam, column, pier or other
structural member, having such bearing on the wall and such
additional support as shall be necessary to comply with the require-
ments of regulation 5.

(2) For the purp oses of this regulation, joists set at distances
apart not exceeding 1 m shall be deemed to compose a distributed
load.

57. (1) Subject to the provisions of regulation 55, where any
part of any wall overhangs any part beneath it, it shall-

(a) be in addition to the required thickness of that wall, and

(b)be corbelled out or otherwise supported to comply with
regulation 5.





(2) The projection of any corbelling shall not exceed 1/3 of the
thickness of the wall immediately below, that corbelling.

58. (1) Where the level of the ground or of the surface of the
site concrete is different on 1 side of a wall to that on the other, the
width of such wall in a building built of bricks or building blocks
shall be not less than 1/4 of such difference of level.

(2) If such difference in level exceeds 1.8 m. the wall shall be
designed and built as a retaining wall and in accordance with
regulation 48 of the Buildifig (Planning) Regulations.

59. (1) Subject to the provisions of paragraph (2)-

(a)a 1 -storey building, other than a domestic building, whose
width measured in the direction of the span of the roof
does not exceed 9 m and the height of whose walls does not
exceed 3 m or

(b) a garage, greenhouse, store. water-closet or other room
(attached to a domestic building) not intended to be used
for habit tion and not exceeding 3 m in height.

may have external walls not less than 100 mm thick.

(2)(a) W ere any such wall exceeds 2.5 m either in height or
lenght it shall be bonded into piers, 1 of which shall be
placed at each end of the wall, not less than 225 mm square
in horizontal section, or of such greater size as may be
required to give adequate stability.

(b)Wher any, such wall exceeds 3 m in length additional such
piers hall be placed in the wall so as to divide the same
into h ngths not exceeding 3 in.

(c)All bedding and Jointing in such walls and piers shall be in
cemeT t mortar.

(d)Such walls shall bear no load other than the distributed
load of the roof. which shall be so constructed that the
walls ire not subject to any lateral thrust therefrom.

60. (1) A load-bearing external or party wall not exceeding
7 m in height and 9 m in length in a building other than a public
building or a building of th e warehouse class. and, subject to the
provisions of regulation 68 a panel wall in any building, may be
constructed as a cavity wall.

(2) NO storey in a building of cavity wall construction shall
exceed a height f 3.5 m.

(3) Cavity walls shall be constructed of solid bricks or building
blocks properly bedded and jointed in cement mortar, and shall
comprise 2 leaves, each not less than 100 mm thick and an interven-
ing cavity not less than 50 mm and not more than 75 mm wide.





(4) The 2 leaves shall be united---

(a)by iron ties so shaped as not to transmit moisture across
the cavity and not less than 20 x 3 mm in cross-section,
well galvanized or otherwise protected from corrosion, or

(b) by ties of such other materials and cross-section as to
comply with the relevant current; British Standard Speci-
fication.

(5) Such ties shall be built into the horizontal bed joints during
erection and placed at distances apart not exceeding 900 mm
horizontally and 450 mm vertically.

(6) Such ties shall also be placed at distances apart not
exceeding 300 mm (measured vertically) within 150 mm of the sides
of all openings.

(7) The cavity shall during construction be kept free from
mortar droppings.

(8) In the case of load-bearing walls the cavity shall extend
downwards at least 150 mm below the level of the low~r damp-proof
course of the wall, and in all walls, wherever the cavity is bridged a
damp-proof course or flashing shall be provided to direct moisture
away from the inner leaf of the wall.

(9) Adequate drainage shall be provided to all cavities through
the outer leaf of the wall. The maximum width of any opening for
drainage purposes shall not exceed 5 mm.

61. Where glass block panels are built into walls other than
party walls-

(a)the opening into which the glass blocks are built shall be so
constructed that no load from the building is transferred to
the glass blocks,

(b)the maximum area of a single panel shall be 9 m' and the
maximum vertical dimension shall be 4.5 m in external
walls or 6 m in internal walls.

62. Every parapet to an external or party wall shall-

(a) where built of bricks or building blocks have-
(i) a thickness of not less than 225 mm. and
(ii) a height not more than 6 times its thickness;

(b)where built of reinforced concrete have a thickness of not
less than 100 mm.

63. (1) The boundary round the site of any building adjacent
to a street or scavenging lane shall be provided with a boundary wall
or fence not less than 1.8 m in height unless exempted by the
Building Authority.

(2) Every boundary wall of bricks or building blocks shall-

(a) be built in cement mortar or cement-lime mortar;





(b)if not exceeding 1.8 m in height, be not less than 100 mm
thick and built solid or honeycombed; and

(c)be provided with buttresses or piers not less than 225 mm
square in horizontal section and not more than 2 m apart
centre to centre which shall be placed-
(i) at all angles of such wall; and
(ii) at each end thereof unless such wall is bonded into
another wall not less in thickness than the buttresses or
piers required..

(d)if exceeding 1.8m in length but not exceeding 3 m in
height, be not less than 225 mm thick.

64.(a) The slenderness ratio of any wall or pier of any storey
height shall be-
(i) in the case of a wall. the ratio of the effective height
to the thickness of the wall, exclusive of plaster or
rendering.
(ii) in the case of a pier. the ratio of the effective height
to the least lateral dimension.

(b)The effective height of a storey height of a wall or pier shall
be as shown in column 2 below-

Support to Wall or Pier Effective Height

(i) Wall with lateral support at 3/4 of the storey height.
of that storey height

(ii) wall without lateral support 1 1/2 times the storey
top of that storey height.
height.

(iii) pier with lateral support at the storey height.
the top of that storey height
(iv) pier without lateral support 2 times the storey,
at the top of that storey height.
height

65. (1) Where, in the case of walls or piers built of bricks or
building blocks, the slenderness ratio of any storey height does not
exceed 1, the compressive stresses in such storey height shall not
exceed those specified in Table XIII for the designated bricks or
building blocks opposite the specified mixture of mortar.

(2) Where the slenderness ratio of such storey height exceeds 1,
the compressive stresses in that storey height shall not exceed the
appropriate stress specified in Table XIII multiplied by the factor
specified in Table XIV for the slenderness ratio of such storey height:

Provided that the slenderness ratio shall not exceed 18.

(3) The compressive stress shall be deemed to be the sum of
the dead and imposed loads distributed uniformly over the area
sustaining such load.





TABLE XIII

Maximum compressive stress in MPa in walls and piers of bricks or
building blocks when the slenderness ratio does not exceed 1



* In accordance with regulation 15 up to 1/4 part of lime may be added to
cement-mortar.

TABLE XIV

Reduction factor under paragraph (2) for slenderness ratio of
walls and piers of bricks and building blocks

Note:The factor for intermediate values of the slenderness ratio shall be determined
by interpolation.

66. (1 ) Where, in the case of walls or piers built of concrete,
the slenderness ratio of any storey height does not exceed 1, the
compressive stresses in such storey height shall not exceed those
specified in Table XV for the designated grade of concrete.

(2) Where the slenderness ratio of such storey height exceeds
1, the compressive stresses in that storey height ~hall not exceed
the appropriate stress specified in Table XV multiplied by the
factor specified in Table XV1 for the slenderness ratio of such
storey height:





Provided that the slenderness ratio shall not exceed-

(a) in the case of a pier, 18;

(b)in the case of a wall with the minimum reinforcement
specified in paragraph (4), 24.

(3) The compressive stress shall be deemed to be the sum of
the dead and imposed loads distributed uniformly over the area
sustaining such load.

(4)(a) Shrinkage reinforcement shall be provided in all con-
crete walls.

(b)The volume of that reinforcement shall be not less than 0.4
per cent of the volume of the concrete in the wall, and half
of that reinforcement shall be disposed vertically and half
horizontally.

(c) The reinforcernent all be disposed near the wall surface
and the spacing of bars shall not exceed 300 mm.

TABLE XV

Maximunt compressive stress in MPa on walls and piers of concrete,
when the slenderness ratio does not exceed 1

Maximum permissible
stress


TABLE XVI

Factor for slenderness ratio of walls and
piers built of concrete



mined by interpolation.





67. (1) The maximum stresses specified in regulations 65 and
66 may be exceeded by not more than 25 per cent where such excess
is caused solely by eccentricity of loading or to lateral forces or to a
combination of both.

(2) Additional stresses of a purely local nature as at girder
bearings, column bases and lintels or other concentrated loads. are
to be calculated and the maximum stress resultinu from these
combined with those provided for in regulations 65 and 66 and
paragraph (1) shall not exceed the permissible stress given in
regulations 65 and 66, as the case may be, by more than 50 per cent.

(3) In the case of walls of building blocks. no reliance
shall be placed on the tensile strength of the bricks or building
blocks.
68. (1) Where an external wall is constructed of materials
used in combination with a framework of steel or reinforced
concrete, any part of that wall which does not sustain and transmit
any load other than tha t due to its own weight and to wind pressure
on its own surface may be deemed to be a separate panel wall.

(2) In every panel wall constructed, otherwise than as a cavity
wall, of bricks, building blocks or plain concrete-

(a) the thickness shall be not less than 225 mm throuahout:

(b) the height shall not exceed 7 m.

(c)either the height or the length (whichever is the less) shall
not exceed 18 times the thickness. and

(d)the base shall not overhang the beam upon which it is
supported, to a greater extent than 1/3 of the thickness of the
panel.

(3) In every panel wall constructed as a cavity wall-

(a)the provisions of regulation 60 shall be complied with
except tlhat the inner leaf may be constructed of solid or
hollow bricks or blocks not less than 100 mm thick..

(b) the heigh shall not exceed 7 m;

(c) either the height or the length (whichever is the less) shall
not exceed 3.5 m;

(d) the base shall not exceed 20 m2; and


(e) the base shall not overhang the beam upon which it is
supported, to a greater extent than 1/3 of the thickness of
the overhanging leaf:

Provided that. if the bottom courses are built solid for
the full thickness of the panel wall to a height above its
base at least equal to that full thickness, the base may.
overhang the beam to an extent not exceeding 1/3 of that full
thickness.





(4) In everv panel wall constructed of reinforced concrete-

(a) the thickness shall be not less than 100 mm; and

(b)the volurne of that reinforcement shall be not less than 0.4
per cent of the volume of the concrete in the wall and of
that reinforcement shall be disposed vertically and half
horizontally.

69. (1) Cladding shall-

(a)be constructed entirely of non-combustible materials,
including the frames and sills of windows and doors;

(b) have its external face constructed of-
(1) glass;
(11) copper or aluminium alloy sheeting:
(iii) sheet iron or steel protected by vitreous enamel; or
(M such other materials as the Building Authority, may
approve.

(2) Cladding shall either--

(a) abut solidly against----
(i) the end of any wall partition or any column which
forms part of an enclosure to a compartment of the
building or which forms part of an enclosure to a staircase
or other vertical shaft; and
(ii) any floor or beam; or

(b)have any voids in these positions filled with non-combus-
tible material to the satisfaction of the Building Authority.

(3) Cladding shall be fixed to the main structure of the
building at intervals not exceeding 3.5 in apart vertically, and 1.5 m
apart horizontally.

(4) The strength, stiffness, stability, and durability of the
cladding shall be to the satisfaction of the Building Authority.

(5) All fixings securing the cladding to the main structure shall
be of stainless steel. phospher bronze. aluminium bronze or other
materials to the satisfaction of the Building Authority.

70. (1) Every party wall shall be carried up to the underside of
the roof.

(2) Where the roof is constructed of combustible materials

(a) no combustible part of such roof shall be carried across the
party wall; and

(b) the roof covering shall be solidly bedded in mortar direct
on the top of the party wall for its whole width and length.

71. No floor or roof joist bond timber or wood plate shall be
built into the thickness of any wall.





72. (1) Every wall built of bricks or building blocks shall
be constructed wA a damp-proof course complying with regula-
tion 23.

(2) Such damp-proof courses shall be constructed-

(a)horizontally through the wall at a height of not less than
150 mm above the highest finished level of the external
ground or paving or the surface of any oversite concrete on
either side of the wall;

(b) horizontally under the coping of a parapet wall,

(c) vertically on the outer face of a wall where the ground
surface on the outside of the wall is higher than any floor
of the building. together with a horizontal damp-proof
course under the floor;

Provided that such damp-proof course may be
omitted where the floor and wall are constructed of
properly water-proofed reinforced concrete of not less
than 200 mm in thickness;

(cl)horizontally through the whole area of the brickwork of a
chimney a6ove the roof and be connected to the apron
flashing.

PART VII

FIREPLACES, FLUES AND CHIMNEYS

73. (1) Where any fireplace or stove is built or placed on any
floor which is constructed of combustible material it shall be
provided with a hearth of concrete, stone or other like incombustible
material, level with the floor, under and before the fireplace or stove.

(2) Such hearth shall---
(a)be solid for a thickness of not less than 150 mm in every
part;
(b) extend not less than 150 mm beyond each side of the
fireplace or stove opening;

(c) extend not less than 450 mm in front of the fireplace or
stove opening;

(d) if of concrete, be reinforced with not less than 300 mm2 of
reinforcement per metre width in each direction; and

(e) be adequately supported.

74. (1) Any wall of bricks or building blocks at the back of a
fireplace shall be not less than 100 mm thick and in the case of an
external or party wall it shall be not less than 225 mm thick.

(2) Such minimum thickness shall be carried up from the level
of the hearth to the level of the ceiling of the room in which the
fireplace is situated:





Provided that where the flue from that fireplace is back to back
with another flue. such thickness shall be carried up to a height of
not less than 300 mm above the level of the top of the fireplace
opening.

(3) The jambs of every fireplace opening shall be not less than
225 mm wide on each side.

(4) The enclosure and breast of every fireplace opening shall
be supported by a lintel of reinforced concrete or steel or an arch of
brick or stone.

(5) Every fireplace shall be lined with refractory fire bricks or
slabs not less than 50 mm thick set in fireclay.

75. (1) Every fire ace shall be provided with a chimney.

(2) Where solid fuel or oil is burnt every fireplace shall have its
own flue.

(3) The flue in every such chimney shall-

(a)where used for a fireplace burning solid fuel or oil be not
less than 200 mm across in any direction;

(b)where used for an open domestic gas fire or other gas fire
appliance---
(i) be not less than 0.013 m2 in cross sectional area; and
(ii be encased in incombustible material not less than
25mm thick exclusive of plastering:

Provided that voids may be left in such material
enclosing the flue and not connected therewith.

(4) Every such chimney shall---

(a) be rendered or pargeted on the inside lined with fireclay.
stoneware or other like incombustible material; and

(b) where used for a fireplace burning solid fuel or oil be made
of solid bricks or building blocks, be properly bonded and
solidly put together with cement mortar, or of plain or
reinforced concrete, not less than 100 mm thick:

Provided that soot doors may be inserted in such
chimneys.

76. (1) Every chimney stack shall be carried up above the
level of the highest point of its intersection with the adjoining roof or
gutter to a height of at least---

(a)450 mm where used in connexion with a gas-fired appli-
ance, or

(b)900 mm where used in connexion with a fireplace burning
solid fuel or oil.





(2) The height of every chimney stack measured from the level
of the highest point of its intersection with the adjoining roof or
gutter to the top of the stack. shall not exceed 6 times the least
horizontal dimension of the stack unless it is adequately secured
against over-turning.

(3) The topmost 6 courses of every chimney stack constructed
of bricks or building blocks shall be laid in cement mortar, or
cement-lime mortar containing not less than 1 volume of cement to
every 6 volumes of sand.

(4)(a) Where the height of a chimney stack measured from
the level of the highest point of its intersection with the
adjoining roof or gutter exceeds 1.5m, the part of such
chimney stack above 1.5 m may be constructed of metal
pipes, adequately stayed to resist wind pressure. and with a
cross sectional area not less tha 3/4 of the cross sectional
area of the chimney stack belolw and in any case not less
than 150 mm in internal diameter.

(b) Such pipes shall be construct - -
(i) of cast iron, not less than 5 mm thick at any point, or
(ii) of mild steel plates not less than 5 mm thick, or
(iii) if used with a gas-fired appliance of steel metal of a
thickness not less than 1 mm.

(c) All metal in flue pipes shall be protected against corrosion.

77. (1) No timber (other than wood plugs) or other combus-
tible material shall be placed in any wall or chirmney within 225 mm
of any flue or the inside of any fireplace opening.

(2) No wood plugs shall be driven into any wall or chimney
within 150 mm of any flue or the inside of any fireplace opening.

(3) No woodwork or other combustible material of the sur-
round of any fireplace opening shall be fixed round that opening
unless it is-
(a)distant at least 150mm measured horizontally and 300 mm
measured vertically from that fireplace opening, and

(b) solidly backed with incombustible material.

78. (1) Every chimney shaft built of bricks shall comply with
the following provisions-

(a)it shall be constructed of suitable solid bricks jointed with
suitable mortar;

(b)it shall be square, circular, or of any regular polygonal
shape, and the outer face shall be built to a batter of at
least 20 mm in every 1 m of height;





(c)the height measured from the base to the top of the
chimney shaft, shall not exceed the least width of the base
multiplied by-
(i) 10 times if the shaft be square,
(ii) 12 times if the shaft be circular or polygonal;

(d)the thickness at its top and for 6 m below its top shall be at
least 225 mm and it shall be increased by 1, brick for every
additional 6 m, or part thereof. measured downwards:

Provided that-
(i) any cap, cornice, plinth, string course or other
departure from plain brickwork; and
(ii) any internal lining,

shall be additional to the thickness of the brickwork
required by this paragraph,

(e) any internal lining shall not be bonded with the brickwork.

(f) any metal used in connexion with the construction of the
shaft shall be properly protected against corrosion;

(g) any footing which may be provided at the base of the
shaft shall pread all round at base by regular offsets and
the space enclosed by, such footings shall be filled in solid
with concrete.

(2) Every chimney shaft built of reinforced concrete shall
comply with the relevant provisions ol' Part XII for the structural
use of reinforced concrete and shall comply with the following
provisions-
(a) the connerete shall be not inferior to that designated Grade
IIIA in regulation 19;

(b)the reinforcement shall be in accordance with the require-
ments of regulation 20 and the concrete cover shall be not
less than 40 mm thick;

(c) the concrete stresses shall not exceed the maximum permis-
sible stresses in regulation 116 or 157 if special or designed
mixes are used:

(d) the stresses in the reinforcement shall not exceed 60 per
cent of the maximum permissible stresses in regulation 117
or 58;

(e) due account shall be taken of the effect of temperature
stresses; and

(f) any lining which may be provided to the shaft shall not be
taken as contributing to the strength of the shaft.

(3) If built of mild steel shall be constructed of steel plates not
less than 5 mm thick and properly stayed and protected against
corrosion.





(4) The foundations of the shaft shall be so proportioned that
the resultant of all loads shall be within the middle third of the
foundations, or if on plied foundations shall cause no tension in
any pile.

(5) In paragraph (1)(g) 'base' means the underside of the
course immediately above the footings, if any, or if there are no
footings the bottom of the chimney shaft.

79. (1) Every open cooking slab (not being a fireplace and not
directly connected to a chimney) constructed or adapted for the use
of coal, charcoal or wood as fuel shall be provided with an
incombustible hood of sheet metal or other material as the Building
Authority may approve, connecting with a chimney.

(2) The bottom edge of such hood shall be not more than 2 m
above floor level and shall cover the area of the cooking slab.

80. No floor or roof of combustible material shall be con-
structed over any fireplace, heating appliance or oven, burning solid
fuel or oil fuel, within 1.5 m of the top of such fireplace, heating
appliance or oven, unless protected with a lining of incombustible
material not less than 5 mm thick, covering a horizontal area of not
less than 10 m2 and so arranged as to give the most eftetive
protection.

PART VIII

ROOFS

81. (1) The roof of every building and of any minor structure
placed above such rool except the doors, and frames of dormers or
sky lights shall be covered with tiles, glass, metal or other incom
bustible material:

Provided that where a roof is constructed entirely of incom-
bustible materials the external covering may consist of-

(a)rock asphalt containing not more than 17 per cent by
weight of bitumen; or

(b)a layer or layers of compressed and impervious felt mem-
brane roofing having an aggregate thickness of not more
than 10 mm bedded down solidly on the roof by viscous
materials.

(2) Where the roof is covered in a manner provided by pro-
viso (b) to paragraph (1) the external layer of such roofing shall
be surfaced with hard incombustible mineral matter incorporated
during manufacture.

Provided that asbestos based roofing felt need not be so
surfaced where the slope of the roof is not greater than 20 degrees
from the horizontal.





82. Every roof shall be-

(a) weatherproof; and

(b)provided with adequate gutters and rain water pipes to
prevent the direct discharge of water upon or over any
footpath or roadway.

83. Every part of a roof, to which access is provided, shall be
protected by parapet walls or railings not less than 1 100 mm in
height from finished roof lev ' cl and so constructed as to inhibit
climbing and the passage of articles more than 100 mm in their
smallest dimension. The lowermost 150 mm of such parapet walls
or railings shall be built solid.

84. Where a ceiling is constructed with a space between it and
the floor or roof above, such space shall be properly protected
against vermin and in the case of a timber floor or roof, such space
shall also be adequately ventilated.

PARTIX

DUTIES OF REGISTERED STRUCTURAL ENGINEER IN STRUCTURAL
USE OF TIMIBE, STEEL AND REINFORCED CONCRETE

85.(1) (a) Where any steel framed or reinforced concrete
structure is designed in accordance with the provisions of
regulation 113 or regulations 157 to 165, the structural
details and calculations required by regulation 8(1)(i) of
the Building (Administration) Regulations shall be pre-
pared and signed by a registered structural engineer.

(b)The construction of any structure so designed shall be
supervised by a registered structural engineer in accord-
ance regulation 37 of the Building (Administration)
Regulations.

(2) Structures may be designed and constructed in prestressed
concrete, shall construction or any other methods and materials,
subject to-

(a) the production of proof to the satisfaction of the Building
Authority regarding the soundness of design; and
(b) the structural details and calculations required by regula-
tion 8(l)(i) of the Building (Administration) Regulations
being repared and signed by a registered structural engineer.


(3) Where the Building Authority is satisfied with the proof of
soundness of design of any structure under paragraph (2)(a), the
construction shall be supervised by a registered structural engineer
in accordance with regulation 37 of the Building (Administration)
Regulations.





PART X

STRUCTURAL USE OF TIMBER

86. (1) Every joist, binder, rafter and purlin shall have a
finished breadth of not less than 35 mm.

(2) Floor boards and boarding to flat roofs shall have a
finished thickness of not less than 16 mm.

87. (1) For the purpose of determings the sizes of ceiling
joists a total load shall be taken of not less than 1 kPa. but for the
purpose of designing the construction supporting those joists. the
total load may be taken as 0.5 kPa.

(2) For the purpose of determining the required thickness of
tongued and grooved floor-boards, an imposed load shall be taken
per meter width of the boarding of not less than the load for slabs
specified in column 4 of Table VII for the type of floor specified in
that Table.

(3) Where plain-edged floorboards are used, each floorboard
shall be capable of resisting, without exceeding the maximum
permissible stress specified in Table XVII. the load for slabs specified
in column 4 of Table VII for the type of floor specified in Table VII.
irrespective of the width of the floorboards.

(4) Subject to the provisions of regulation 86(2). the required
thickness of floorboards shall be not less than the thickness deter-
mined by calculation plus 3mm for wear.

88. (1 ) Subject to the provisions of regulation 92, the stresses
in structural timber, other than posts and struts. shall not exceed the
maximum permissible stresses specified in Table XVII.

TABLE XVII

Maximum permissible stresses instructural timber (other than
posts and struts) in M Pu
1 Class of timber

2 3
Kind of stresses
A B

Flexural stress in extreme fibre, (other than floor-
boards) with adequate lateral restraint against
winding or buckling ...................... .... 7.0 5.5
Flexural stress in extreme fibres of floorboards 5.5 5.5
Shear stress in direction of grain 0.7 0.7
Compressive stress perpendicular to grain 2.4 1.7
Tension in direction of grain 10.3 8.3

Modulus of elasticity (mean) ...... 11 000 8 300
Modulus of elasticity (minimum) .. . 7 000 5 200





(2) The mean value of the modulus of elasticity shall only be
used for rafters and floor and ceiling joists and, in all other cases, the
minimum value of the modulus of elasticity shall be used.

(3) Where the direction of the load is inclined to the direction
of the member, the permissible compressive stress for the inclined
surface shall be determined by the formula:

Cbi = CbtCb/Cb sin2 0 + Cbt cos2 0
where - Cb is the permissible compressive stress parallel to
the grain,

Cbi is the permissible compressive stress for the
inclined surface,

Cbt is the permissible compressive stress perpendi-
cular to the grain, and

0 is the angle between the direction of the load and
the direction of the grain.

(4) The shear strength at square cornered notches at the ends
of a flexural member shall be calculated by using the effective depth
(dc)shown in the following figure:

Beam notched at end

and also a permissible shear stress equal to that specified in Table
XVII multiplied by the reduction factor K where-
K= effective depth (de)/total depth (d)

(5) For the purpose of this regulation, adequate lateral restraint
to a flexural member against winding or buckling shall be deemed to
have been provided if the distance between the lateral restraints does
not exceed 50 times the breadth of the member.

89. (1) Subject to regulation 92, the compressive stress in the
direction of the grain of a post or strut shall not exceed the
maximum permissible stress specified in Table XVIII for the ratio of
effective length (l) to the least radius of gyration (k) (or the least
lateral dimension (b) in respect of solid members of rectangular
cross-section only) specified in that Table.





(2) In a post or strut the ratio of effective length (1) to-
(a) least radius of gyration (k), shall not exceed 200; or
(b) least lateral dimension (b), shall not exceed 58.
(3) No post or strut shall be so notched as to reduce its
dimensions below those found necessary by calculation.

TABLE XVIII

Maximurn permissible compressive stresses in posts and struts in MPa

Note: The maximum permissible compressive stress for intermediate values of l/k or
l/b shall be obtained by interpolation between the 2 nearest stresses for the
class of timber used.

90. For the purpose of regulation 89 the effective length of a
post or strut shall be that specified in Table XIX for the type of post
or strut specified in that Table.

TABLE M

Effective length of posts and struts

1 2

Effective length (L= length of
Type of post or strut post or strut between centres
or restraining members)

Properly restrained at both ends in position
and direction ...............0.7 L
Properly restrained at both ends in position
and at 1 end in direction ...0.85 L
Properly restrained at both ends in position
but not in direction ........L
Properly restrained at 1 end in position and
direction and at the other end partially
restrained in direction but not in position 1.5 L
Properly restrained at 1 end in position and
direction but not restrained at the other end 2.0 L

Note:The effective length of a post or strut of a type not specified in this Table
shall be determined to the satisfaction of the Building Authority.





91. The calculated deflexion of any joist or binder shall not
exceed 1/333 of its length.


92. (1) The maximum permissible stresses specified in this
Part may be increased by 25 per cent for members forming part of
the roof construction of a pitched roof when the calculations are
based on all loads including imposed load.
(2) No increase in the maximum permissible stresses specified
in this Part shall be allowed when the calculations are based on all
loads other than imposed load.

93. Members subject to combined bending and axial compres-
sion shall be so proppftioned that the quantities
f/F + fb/Fb

shall not exceed--

(a) unity, or members with a ratio of effective length to least
radius of gyration not exceeding 20; and
(b) 0.91 for members where that ratio exceeds 20,
where-f =axial compressive stress,
F =maximum permissible compressive stress
in posts and struts,
fb =maximum compressive stress due to
bending, and
Fb =maximum permissible compressive flexural
stress in extreme fibres of beams.

94. (1) All framing, tenoning, spiking or nailing. bolting,
strapping and other jointing shall be so designed as safely to
transmit the load and stresses to which it will be subjected and the
execution of all such jointing shall be to the satisfaction of the
Building Authority.
(2) Where bolts are used, adequate plates or washers shall be
used to preserve the grain of the timber from crushing.

PART XI

STRUCTURAL USE OF STEEL

95. (1) Structural steel shall be cleaned of loose scale and rust
and, except where it is to be solidly encased with concrete, brickwork
or other similar non-combustible material, shall be either-

(a) thoroughly coated with at least 2 coats of paint or boiled
oil, 1 coat of which may be applied before erection; or
(b)provided with such other protection against corrosion as
the Building Authority may approve.
(2) The coatings of paint or boiled oil, or other protection
against corrosion, shall, in the case of all surfaces inaccessible after
erection (except surfaces held in direct contact by riveting or
intermittent welding) be applied before erection.





96. (1) Subject to the provisions of Part XVI (Fire Resisting
Construction). where a column or beam is situated wholly or partly
in an external wall or wholly or partly within a recess in a party wali,
that column or beam shall be solidly encased with bric~work,
concrete or other similar material not less than-
(i)100 mm thick where the encasement of a column is exposed
to the weather; and
(ii) 50 mm thick where not so exposed.

(2) Where structural steel may be adversely affected by mois-
ture from the adjoining earth. it shall be solidly encased with
concrete not less than 100 mm thick.

(3) For the purpose of this regulation any concrete used in the
encasement of steelwork shall be not in inferior to that designated
Grade III in regulation 19.

97. (1) Subject to the provisions/of regulations 97(3), (4) and
(5), 99, 101 and 106, the stresses on structural steel (other than
columns and struts), shall not exceed the maximum permissible
stresses specified in Table XX.

(2) In compound or built-up sections formed with different
thicknesses of high yield stress structural steel, the maximum permis-
sible stress for the whole of the section shall be taken as that for the
greatest thickness of material used, except that for shear on webs,
the maximum permissible stress shall be that specified for the
thickness of the web itself.

TABLE XX

Maximum permissble stresses on structural steel
(other than columns and struts) in MPa

1 2 High yield stress
2 structural steel
complying with the
appropriate provisions
of BS 4360: 1972
Mild steel
comphing
with the 3 4
Part of structure And appropriat
kind of stress appropriate prvisions
of B5
4360:1972
For material For material
not exceeding exceeding
25 mm in 25 mm in
thickness or thickness or
diameter diameter diameter

1. For parts in tension-
(a) on the net section for axial stress 140 190 170
(b) flexural stress in extreme fibres of slab
bases ... ...... 185 185 185
(c) flexural stress in extreme fibres on the
net section of-
(i) beams and girders (other than
plate girders) ..... 150 210 190
(ii) plate girders ... 145 200 185
(d) on shop rivets for axial stress 80 110 100
(e) on field rivets for axial stress 60 85 80
(f) on the net section of bolts for axial
stress ............... 80 110 100






Webs of beams shall possess or be provided with adequate stiffness to prevent
buckling.
(b) on shop rivets and turned bolts 90 130 115
(c) on field rivets 80 110 110
(d) on black bolts 60

The strength of rivets and bolts in double shear may be taken as 2 times that for
single shear.
(e) other than on webs, rivets and bolts 100 140 120
........................ ............................





Note. l is the length between effective lateral supports.
kyy is the least radius of gyration of the beam or girder section.
d is the clear distances between flange angles (or flange plates where there are
no flange angles) or web stiffeners, whichever is the lesser.
t is the thickness of the web.
ft,fa,fs are the maximum permissible tensile. compressive and shear stresses,
respectively, in the parent metal or in the weld metal, whichever is
the lesser.

(3) Subject to paragraph (4), where a beam or girder is of
symmetrical section, the maximum permissible stresses specified in
item 2(b) of Table XX may be increased by the percentage specified
in Table XXI for the ratio (kxx /kyy) of the greatest to the least radius
of gyration of the section of that beam or girder.

TABLE XXI

Percentage increase for shape factor

1 2
kxx/kyy Percentage increase
5.0 5.0
4.5 15.0
4.0 30.0
3.5 or less 50.0

Note: (1) kxx is the greatest radius of gyration of the beam or girder section.
(2) The percentage increase for intermediate values of the ratio kxx/kyy shall
be obtained by linear interpolation between the 2 nearest values.





(4)(a) In no case shall the flexural stresses of a beam or
girder of symmetrical section exceed the appropriate stress
specified in column 2 of Table XXII.

(b)The percentage increase permitted by paragraph (3) shall
not be taken into account in regulation 100.

TABLE XXII

Maximum flexural stresses of a beam or girder
of symmetrical section

1 2

MPa

1. Steel complying with the ppro iate provisions of
BS 4360: 1972-
(a) beams or girders, other than plate girders 150
(b) plate girders ............................................ 145
2. High yield stress structural steel complying with the
appropriate provisions of BS 4360: 1972-
(a) beams and girders, other than plate girders-
(i) material not more than 25 mm thick 210
(ii) material more than 25 mm thick 190
(h) plate girders---
(i) material not more than 25 mm thick 200
(ii) material more than 25 mm thick 185

(5) Beams and girders with equal flanges may be designed as
cased beams provided the following conditions are fulfilled:

(a) the section is of single web and I-form or of double open
channel from with the webs not less than 40 mm apart;

(b) the beam is unpainted and is solidly encased in dense
concrete not inferior to that designated grade IIIA in
regulation 19;

(c)the minimum width of solid concrete encasing is at least
equal to (b + 100) mm, where b is the width of the steel
flange in mm,

(d)the surface and edges of the flanges of the beam have a
concrete cover of not less than 50 mm;

(e)the casing is effectively reinforced with wire to BS 4482:
1969. The wire shall be at least 5 mm diameter, and the
reinforcement shall be in the form of stirrups or binding at
not more than 150 mm pitch. and so arranged as to pass
through the centre of the covering to the edges and soffit of
the lower flange;

(f) the beam or girder has a depth not exceeding 750 mm (over
plating where used) and a width not exceeding 450 mm.

(g) the beam or girder is not of a box section. The least
radius of gyration (kyy) may be deemed to be equal to 0.2
(b+ 100) mm and the radius of gyration (kxx) shall be
deemed to be equal to that of the uncased section:





Provided that in no case shall the maximum flexural
stress in extreme fibres of the eased section exceed either---
(i) 1 ' times the maximum permissible stress on the
uncased section of that beam or girder; or
(ii) that specified in Table XXIII,
whichever is the lesser stress.

TABLE XXIII

Maximum flexural stresses in extreme fibres of the
cased section of a beam or girder

1 2

MPa

1. Steel complying with the appropriate prOxisions of
BS 4360: 1972-
(a) beams or girders other than plategirders 150
(b) plate girders ................................ 145

2. High Yield stress structural steel complying with the
appropriate provisions of BS 4360: 1972---
(a) beams and girders, other than plate girders-
(i) material not more than 25 mm thick 210
(ii) material more than 25 mm thick 190
(b) plate girders-
(i) material not more than 25 mm thick 200
(ii) material more than 25 mm thick

98. (1) The permissible ratio of effective column or strut
length (l) to least radius of gyration (k) shall not exceed the
following values:
(a) for any member carrying loads resulting from dead
and imposed loads ...................180
(b) for any member carrying loads resulting from wind
forces only, provided the deformation of such mem-
ber does not adversely affect the stress in any part of
the structure carrying loads resulting from dead
and imposed loads ...................250

(c) for any member normally acting as a tie in a roof
truss but subject to possible reversal of stress due to
the action of wind suction .........350

(2) Subject to the provisions of paragraph (3) and of regula-
tions 99 and 100 the axial stress on column and struts of steel
shall not exceed the maximum permissible axial stress specified in
Table XXIV for the ratio l/k specified in that Table.





TABLE XXIV

Maximum permissible axial stress on columns and struts in MPa

1 Steel complying with the ap priate provisions of-

2 BS 4360: 1972

Ratio
3 4
l/k
BS 4360: 1972
Grade 43 Not exceeding Exceeding 25 mm
25mm in thickness in thickness

0 140 190 170
10 130 180 160
20 120 170 150
30 115 160 140
40 110 145 130
50 100 135 120
60 95 120 110
70 85 110 00
so 80 100 95
90 70 85 80
100 65 75 70
110 60 65 60
100 50 55 55
120 45 50 50
140 40 45 40
150 15 40 35
160 31 35 32
170 29 31 29
180 26 27 26
190 53 25 25
200 21 28 22
210 20 20 20
220 19 19 19
23O 17 17 17
240 15 15 15
250 14 14 14
300 9 11 11
350 8 8 8


Note: The maximum permissible axial stress for intermediate values of l/k shall be
obtained by interpretation between the 2 nearest stresses for the kind of steel
used.

(3) For the purpose of calculating the maximum permissible
axial stress on column or strut where that column or strut-

(a) is of I-section;

(b) has a single web;

(c) does not exceed 750 mm in depth over plating where used;

(d) is solidly encased in concrete not inferior to that designated
Grade IIIA in regulation 19;

(e)the minimum width of solid concrete encasing is at least
equal to b+ 100 mm, where b is the width of the steel flange
in mm;





(f)the surface and edges of the flange of the steel section shall
have a concrete cover of not less than 50 mm; and
(g)the casing is effectively reinforced with wire to BS 4482:
1969 of at least 5 mm diameter, and the reinforcement shall
be in the form of stirrups or binding at not more than 150
nim pitch, and so arranged as to pass through the centre of
the concrete cover,
the least radius of gyration (kyy) may be deemed to be equal to 0.2
(b+ 100) mm and the radius of gyration (kxx) shall be deemed to be
equal to that of the uncased section:

Provided that in no case shall-

(i) the said stress exceed 1 1/2 times the ximum permissible
stress on the uncased section of that column or strut; and

(ii) the ratio (l/k) of that uncased sections exceed 250.

(4) In compound or built-up sections formed with different
thicknesses of high yield stress structural steel, the maximum permis-
sible stress for the whole of the section shall be taken as that for the
greatest thickness of material used.

99. The maximum permissible esses and the increases per-
mitted thereon specified in regulations 97, 98 and 100 for beams.
girders, columns and struts and all their connexions may be in-
creased by 25 per cent when the calculations are based on all loads
including wind load:

Provided that-

(a)the said stresses and increases are not exceeded when the
calculations are based on all loads other than wind load;
and

(b) the increase permitted by this regulation shall not apply to
the stresses specified in regulations 97 (in respect of slab
bases and parts in bearing only), 101 and 106.

100. (1) Members subject to both axial compression and bend-
ing stresses shall be so proportioned that the quantity

fa/Fa + fbc/Fbc

does not exceed unity at any point,
where fa = the calculated average axial compressive stress;
Fa = total permissible axial stress on columns and
struts;

fbc= the maximum resultant compressive stress due
to bending about both principal axes; and
Fbc= total permissible compressive flexural stress in
extreme fibres of beams and girders.

(2) Members subject to both axial tension and bending
stresses shall be so proportioned that the quantity





fl/Fl + fbt/Fbt

does not exceed unity at any point.
where ft= the calculated axial tensile stress;
Ft = total permissibe axial stress in tension;
fbt = the maximum resultant tensile stress due to
bending about both principal axes; and
Fl =total permissible tensile flexural stress in
extreme fibres of beams and girders.

(3) In paragraphs (1) and (2) 'total permissible' means, in
relation to any stress, the maximum permissible stress specified in
regulation 97 or 98 (as the case may be) plus, where applicable, the
increase on the maximum permissible stress permitted in respect of
wind load under regulation 99.

101. The maximum permissible stresses in grillage beams (other
than hollow compound girders) may exceed the stresses specified in
Table XX by 331/3 per cent where-
(a)the beams are entirely embedded in concrete not inferior to
that designated Grade IIIA in regulation 19; and
(b) the beams are spaced apart so that the distance between
the edges of adjacent flanges is not less than 75 mm; and
(c)the thickness of the concrete cover on the top of the upper
flanges and at the outer edges of the sides of the outermost
beams and at the ends is not less than 100 mm; and
(d) the concrete is properly compacted solid around all beams.

102. For the purpose of regulation 98, the effective length of a
column or strut shall be that specified in Table XXV for the type of
column or strut specified in that Table.

TABLE XXV

Effective length of columns and struts

1 2
Effective length (L= length
of column or strut
Type of column or strut between centres of
restraining members)

Properly restrained at both ends in position and
direction ............................................. 0.7 L
Properly restrained at both ends in position and
at 1 end in direction 0.85 L
Properly restrained at both ends in position but
not in direction ............... L
Properly restrained at 1 end in position and
direction and at the other end partially
restrained in direction but not in position 1.5 L

Properly restrained at 1 end in position and,
direction but not restrained at the other end. 2.0 L

Note: The effective length of a column or strut of a type not specified in this Table
shall be determined to the satisfaction of the Building Authority.





103. (1) Both ends of each length of a column. other than a
column of solid round section with shouldered ends, shall be
properly prepared and dead square over the whole area of the ends.

(2) Column joints shall be close butted and the caps, base-
plates and joint seating plates shall be in effective contact over the
whole of the column end.

(3) This regulation shall not apply where sufficient gussets and
rivets are provided to transmit the entire load.

104. (1) The foot of every column, other than a column of
solid round section, shall have affixed thereto either a base-plate or a
slab or bloom base.

(2) Slab or bloom bases shall be properly machined over the
bearing surfaces and shall be in effective contact over the whole area
of the machined end of the column.

(3) Columns of solid round section shall be provided with caps
and bases, the bearing surfaces of which shall be properly machined.
Those caps and bases shall be not less than 1.5 (d+ 75) mm in length
or diameter, where d is the diameter of the column. or. where the
column has a reduced end. If those columns have shouldered ends,
the shoulders shall also be properly machined and the caps and bases
shall be properly machined after being shrunk or screwed on.

(4) A bearing surface which is to be grouted directly to a
foundation need not be machined if that bearing surface is true and
parallel to the machined upper face.
(5) Caps, bases, base-plates and slab or bloom bases shall be
of sufficient thickness to transmit and distribute load without
exceeding the maximum stresses specified in regulation 97.

(6) (a) When the slab alone will distribute the load uniformly,
the minimum thickness of a retangular slab shall be:

r= [3w/P (A 2- B 2/4)]

where- t is the slab thickness in mm;
w is the pressure or loading on the underside of
the base in M Pa;
p is the permissible flexural stress in extreme
fibres of slab bases in MPa.
A is the greater projection of the plate beyond
the column in mm, and
B is the lesser projection of the plate beyond the
column in mm.





(b)For solid round steel columns in cases where the loading
on the cap or under the base is uniformly distributed over
the whole area including the column shaft, the minimum
thickness, in mm, of a square cap or base shall be:

t = 9W/16p x D/D-d

where- t is the thickness of the plate in mm;
W is the total ~Xial load in kN;
p is the permissible flexural stress in extreme
fibres of slab bases in MPa,
D is the length of the side of cap or base in mm,
and
d is diameter, in mm, of the column or, where
the column has a reduced end, of the reduced
end.

(e)For other cases calculations shall be made, based on the
allowable stress of 185 MPa.

105. (1) All column joints shall be designed and constructed to
transmit safely all the forces to which they are subjected.

(2) (a) Column joints in which the resultant unit stress is
wholly compressive and which depend on contact for the
transmission of load shall be sufficiently spliced to retain
the members in place.

(b) Each splice plate shall extend above the joint to a distance
at least equal to the maximum breadth of the column
flange or 150 mm, whichever is the greater dimension, and
shall extend below the joint to a similar distance.

(c) Where the whole of the end of a superimposed column is
not in effective contact with the column beneath, a seating
plate of adequate thickness, which shall extend the full
depth and width of the lower column, shall be interposed
between the ends of the columns.

106. (1) The strength of filler floor beams solidly encased in a
concrete floor slab shall be calculated by either of the following
methods-

(a)on the basis of the combined moment of inertia of the steel
and the surrounding concrete (calculated as in reinforced
concrete neglecting the strength of concrete in tension), in
which case the flexural stress in extreme fibres shall not
exceed 150 M Pa.

(b) on the basis of the section modulus of the fillers alone, in
which case the flexural stress on extreme fibres may be
taken as (160+0.6t) MPa. where t is the number of mm,





not exceeding 75, of structural concrete cover to the
compression flanges of the filler joists:

Provided that where the underside of the slab is flush
with the bottom flanges of the filler joists. no allowance is
to be made for t in respect of support moments, but,
nevertheless, if the top flanges are covered, the allowance
for t may be made in respect of the midspan moments.

(2) The spacing of filler joists centre to centre shall not exceed
the minimum thickness of the structural concrete slab multiplied by
the value n specified in Table XXVI for the imposed load specified in
that Table, unless suitable transverse reinforcement is provided to
the satisfaction of the Building Authority.

TABLE XXVI

Value of n for the spacing of filler joists

1 2

Imposed load in kPa of floor area Value n

Not exceeding 2.5 .................... 10
Exceeding 2.5 but not exceeding 5.0 .......... 8
Exceeding 5.0 but not exceeding 7.5 7
Exceeding 7.5 but not exceeding 10.0 6
Exceeding 10.0 ...............5

107. (1) The calculated deflexion of any beam (other than a
filler floor beam) shall not exceed 1/325 of the span.

(2) The span of any filler floor beam solidly encased in
concrete shall not exceed 35 tinies the depth measured from the
bottom flange of the filler beam to the top surface of the structural
concrete or 12 times that depth in the case of cantilevering fillers.

(3) The span of any beam composed of steel (other than a filler
floor beam) carrying a uniformly distributed load only and comply-
ing with the appropriate provisions of-

(a) BS 4360:1972, Grade 43, shall not exceed 20 times its depth

(b) BS 4360:1972, Grade 50, shall not exceed 13 times its depth

unless the calculated deflexion does not exceed 1/325 of the span.


108. A flange plate or web plate of a column shall be not less
than 10 mm thick. In all other cases, structural steel shall be not
less than 6 mm thick, except-

(a)for standard rolled steel joists, standard rolled steel
channels and packings;





(b) where rust-resisting steels are used; and

(c)where galvanizing or other special provision is made
against corrosion.

109. (1) Bolts shall be provided with washers under the nuts so
that no part of the threaded portion of any bolt is within the
thickness of the parts bolted together.

(2) Shanks of bolts shall project at least 1 full thread beyond
the nuts which shall be so secured as to avoid the risk of their
becoming loose.

(3) The heads of nuts and bolts shall have a true bearing and
taper washers shall be provided where necessary to give that bearing.

(4) The provisions of regulation 110 relating to rivets shall
apply to bolts.

110. (1) The distance from the edge of a rivet hole to the edge
of the plate, bar or member shall be not less than-

(a) the diameter of the rivet, for rolled edges, and

(b) the diameter of the rivet plus 6 mm, for sheared edges.

(2) Rivets shall be so spaced that their centres shall not be
closer together than 3 times the diameter of the rivets.

(3) subject to the provisions of paragraph (7), straight line
pitch in riveted beams, columns or other members shall not exceed
16 times the thinkness of the thinnest outside plate, with a maximum
of 150 mm for parts in compression and 200 mm for parts in tension.

(4) Where 2 rows of staggered rivets occur in 1 flange of a
single angle, the straight line pitch in the direction of stress shall not
exceed 1 1/3 times the distance specified in paragraph (3) in each line.

(5) Where 2 or more flange plates are used, the edge distance,
from the centre line of the nearest rivets connecting the plates to the
web construction, shall not exceed 12 times the thickness of the
thinnest outside plate, and where that edge distance exceeds 9 times
that thickness, tacking rivets shall be introduced connecting those
flange plates together.

(6) Where a single flange plate is used, the edge distance
referred to in paragraph (5) shall not exceed 9 times the thickness of
that plate.

(7) Where tacking rivets are used, the straight line pitch shall
not exceed 24 times the thickness of the thinnest outside plate or 300
mm, whichever is the lesser dimension.

(8) Where a tension member is composed of 2 angles back to
back, the pitch of tacking rivets shall not exceed 1000 mm, and





where a compression member is similarly composed the pitch shall
not exceed 750 mm, or 40 times the least radius of gyration of either
angle, whichever be the lesser dimension:

Provided that tacking rivets on the connected legs of angles may
be staggered.

(9) In paragraphs (7) and (8) 'tacking rivets- means rivets
connecting flange plates together, but not being subject to calculated
stress.

111. (1) Notwithstanding the provisions of regulations 103(3)
and 112(2), welded construction may be used a ' rid shall be carried
out in conformity with the appropriate provisions of BS 5135:1974.

(2) Due account shall be taken in the design of the effects of
any rigidity attributable to welding.

(3) The Building Authority may require the employment of
properly qualified welding supervisor and welders with approved
qualifications for the type of work required as specified in Chapter 6
BS 449:Part 2:1969 for the execution of welded construction.

(4) During construction, the Building Authority may require
from time to time non-destructive tests to be carried out on the
welded structure.

112. (1) As much of the work of fabrication of all steelwork as
is reasonably practicable shall be completed in the works where the
steelwork is fabricated.

(2) Except as provided in paragraphs (3) and (4), rivets or
turned bolts of driving fit shall be used for all work of fabrication
and for field connexions.

(3) Black bolts may be used in cases where no adverse effects
on the structure would result from slipping of the bolts, and where
suitable dead bearings formed by seating plates, packings, brackets
or the like are provided to resist the whole of the shear forces
involved.

(4) The requirements of paragraph (3) as regards dead bear-
ings shall not apply to

(a) roof trusses;

(b) the end connexions of secondary floor beams; or

(c) where, having regard to the particular circumstances of the
case, the Building Authority is satisfied that dead bearings
may be omitted.

(5) Bedding of column bases and bearings of beams and
girders shall be.carried out with Portland cement grout or mortar, or
fine concrete in accordance with the requirements of clause 76 a BS
449: Part 2:1969.











(6) During erection the work shall be securely bolted or
otherwise fastened, and if necessary temporarily braced, so as to
make adequate provision for all erection stresses and conditions,
including those due to erection equipment and its operation. Neither
riveting, permanent bolting or welding shall be done until proper
alignment has been obtained.

(7) All structural steel at the site shall be stored and handled so
that members are not subjected, to excessive stresses and damage.

113. (1) Notwithstandinig the provisions of regulations 97, 98
and 100, steel framed structures may be designed and constructed in
accordance with the relevant provisions of BS 449:Part 2:1969:

Provided that the structural details and calculations required by
regulation 8(1)(i) of the Building (Administration) Regulations shall
be prepared and signed by a registered structural engineer.

(2)The registered structural engineer appointed for such
design or his successor under section 4(2) of the Ordinance shall be
responsible for the supervision of the structural work.

PART XII

STRUCTURAL USE OF REINFORCED CONCRETE

114. (1) Reinforcement shall be free from loose mill scale.
loose rust, oil and other matter which might affect adversely its
proper function with concrete.

(2) The effective diameter of a bar whose cross-section is
constant along its length shall be the diameter of a circle having the
same area as the cross-section of the bar.

(3)The effective diameter of a bar whose cross-section varies
along its length shall be the diameter of a circle having an area equal
to the least area of the bar. An allowance not exceeding 3 per cent
may be added to the least area of the cross-section for any non-
continuous ribs.
(4) Only one grade of deformed bars may be used on a site.
(5)(a) Mild steel and high-tensile or medium high-tensile
steel for main reinforcement shall not be used together in
the same member.

(b)For the purpose of this paragraph, 'member' means any
column, simple beam, continuous beam or slab.

115. (1) Subject to the provisions of Part XVI (Fire Resisting
Construction) the minimum thickness of concrete cover to reinforce-
ment (exclusive of plaster rendering or other applied covering or
decorative finish) shall be-

(a)for each end of a reinforcement. not less than 25 mm or 2
times the diameter of that reinforcement, whichever is the
greater;





(b)for a longitudinal reinforcement in a column, not less than
40 mm or the diameter of that reinforcement, whichever is
greater:

Provided that in a column whose least lateral dimen-
sion is 200 mm or less and whose reinforcement does not
exceed 15 mm in diameter the minimum cover shall be not
less than 25 mm;

(c)for a longitudinal reinforcement in a beam not less than 25
mm or the diameter of that reinforcement, whichever is the
greater;

(d)for any other reinforcement not less than 15 mm or the
diameter of that reinforcement, whichever is the greater.

(2) Where reinforced concrete is exposed to the weather the
minimum cover specified in paragraph (1) shall be increased by not
less than 15 mm

(3) Where reinforced concrete is cast in contact with earth the
minimum thickness of cover shall be 75mm.

(4) Where reinforced concrete (other than reinforced concrete
piling) is cast against formwork and subsequently may be in contact
with earth the minimum thickness of cover shall be 50 mm.

(5) The minimum cover to all reinforcement, including lateral
reinforcement, in concrete piling shall be 40 mm.

(6) The Building Authority may require the cover to be
increased in marine works or where the concrete is exposed to
particularly corrosive conditions.

116. (1) Subject to the provisions of regulations 118 and 120
the compressive, shear and bond stresses in reinforced concrete
shall not exceed the maximurn permissible stresses specified in
Table XXVII for the grade of concrete used.

TABLE XXVII

Maximum premissible stresses in ordinary and quality A
concretes in reinforced concrete in MPa

1 Compression 4 5 6

2 3
Designation Shear Average Local
due to bond bond
bending direct

Grade I .......6.7 5.1 0.7 0.8 1.2
Grade II ......5.9 4.4 0.6 0.7 1.1
Grade Ill .....5.2 3.9 0.5 0.6 0,9
Grade IA ......10.0 7.6 0.9 1.0 1.5
Grade IIA .....8.5 6.5 0.8 0.9 1.4
Grade IIIA ....7.0 5.3 0.7 0.8 1.2





(2) Where the length (L) of a beam between adequate lateral
restraints exceeds 20 times the breadth (B) of its compression flange,
the compressive stress in the concrete shall not exceed the maximum
permissible stress specified in Table XXVII multiplied by the co-
efficient specified in Table XXVIll for the appropriate LIB ratio.

TABLE XXVIII

Stress reduction coefficients for beams

(1) (2) (3) (4) (5) (6)

Slenderness ratio L/B .....20 30 40 50 60
Coefficient ....1.00 0.75 0.50 0.25 0

Note: Intermediate values shall be found by linear interpolation.

117. (1) Subject to the provisions of regulations 118 and 120,
the tensile and cornpressive stresses in reinforcement shall not exceed
the maximum permissible stresses specified in Table XXIX for each
kind of stress.

TABLE XXIX

Maximum permissible stresses in reinforcement in reinforced concrete

1 Maximum permissible stresses in
reinforcement MPa

Mild steel complying 4
with BS 449:1969

2 3
Kind of stress
Not Steel with minimum
Exceeding Exceeding yield point fy MPa
40mm 40 mm


Tension other than tension in
shear reinforcement 125 110 0.5fy or 185 which-
.................. ever is the lesser
Tension in shear reinforcement 125 110 0.5.fy or 140 which-
.................. ever is the lesser
Compression in longitudinal rein-
forcemen in axially loaded
columns and in main reinforce-
ment in beams and slabs where
the compressive resistance of the
concrete is not taken into
account ......... 125 110 0.5fy or 140 which-
................. ever is the lesser

Compression in longitudinal rein- The calculated compressive stress in the sur-
forcement in columns other than rounding concrete multiplied by the modular
axially loaded columns and in ratio but not exceeding
main reinforcement in beams
and slabs where the compressive
resistance of the concrete is
taken into account 125 110 0.5 fy or 140 which-
................. ever is the lesser





(2) In a slender beam to which regulation 116(2) applies, the
stress in any compression steel shall not exceed the permissible stress
specified in Table XXIX for compression in main reinforcement
multiplied by the appropriate coefficient specified in Table XXVIII.

(3) For the purpose of this regulation the modular ratio shall
be taken as 15.

118. (1) Where a reinforced concret column has a ratio of
effective column length to least lateral dimension not exceeding 15,
the stresses in that column shall not exceed the maximum permis-
sible stresses specified in regulations 116 and 117.

(2) Where a reinforced concrete column has a ratio of effective
length to least lateral dimension exceeding 15 and not exceeding 36,
the stresses in that column shall not exceed the maximum permis-
sible stress specified in regulations 116 and 117 multiplied by the
coefficient specified in Table XXX for the appropriate ratio.
(3) The stress in a column due to a combination of direct load
and bending action shall not exceed the maximum permissible stress
for bending specified in regulations 116 and 117 multiplied by the
coefficient specified in Tabel XXX for the appropriate ratio of length
to least lateral dimension.

Provided that the direct stress shall not exceed the stress
specified in paragraph (2).

TABLE XXX

Stress reduction coefficients for slender columns
1 2

Ratio of effective column length Coefficient
to least lateral dimension
15 1.0
18 .9
21 .8
24 .7
27 .6
30 .5
33 .4
36 .3

Note:The coefficient for intermediate ratios of effective column length to least
lateral dimension shall be determined by interpolation.


(4) The ratio of effective column length to least lateral dimen-
sion for any reinforced concrete column or strut shall not exceed 36.





119. For the purpose of regulation 118 the effective length of a
column shall be-

(a)in the case of a column specified in Table XXXI, that
specified in column 2 of that Table, and

(b)in the case of a column not so specified. that determined to
the satisfaction of the Building Authority.

TABLE XXX1

Effective coumn length of reinforced concrete columns

1 2
Type of column Effective column length
(L = length of column between
centres of restraining members)

Properly restrained at both ends in position and
direction ...........; . .7 L
Properly restrained at both ends in position and
at 1 end in direction ........ 85 L
Properly restrained at both ends in position but
not in direction ............................ L
Properly restrained at l end in position and
direction and at the other end partially
restrained in direction but not in position . --- 1.5 L
Properly restrained at 1 end in position and
direction but not restrained at the other end 2.0 L

120. The siresses in reinforced concrete may exceed the per-
missible stresses specified in regulations 116, 117 and 118 by not
more than 25 Per cent:

Provided that--

(a)such excess is solely due to stresses induced by wind
loading, and

(b)except as provided in regulation 158(2) the maximum
stress in reinforcement shall in no case exceed 185 M Pa.

121. (1) The aggregate cross-sectional area of the longitudinal
reinforcements in a reinforced concrete column shall be not less than
0.8 per cent nor more than 4 per cent of the gross cross-sectional area
of that column required to transmit all the load.

(2) Where the longitudinal reinforcement in any column is
continuous without laps and where the least lateral dimension of the
column is not less than 375 mm, the maximum percentage of the
longitudinal reinforcement may be increased to 8 per cent.

(3) A reinforced concrete column having helical reinforcement
shall have not less than 6 longitudinal reinforcements placed
equidistantly around the inner circumference of, and in contact
with, the helical reinforcement.





(4) At each lap in each longitudinal reinforcement, the spliced
reinforcements shall over-lap longitudinally through a distance of
not less than-

(a) (1) 24 times the diameter of the smaller reinforcement
for compressive reinforcement: and
(11) 30 times the diameter of the smaller reinforcement
for tensile reinforcement; or

(b)a sufficient distance to develop the force in thOeinforce-
ment by bond. as calculated in accordance wi regulation
141,

whichever is the greater dimension.

122. (1) (a) A reinforced concrete column shall have trans-
verse or helical reinforcement so disposed as to provide all
necessary restraint against the buckling of each of the
longitudinal reinforcements. Every bar in a column near
the face should be properly link .

(b) The transverse or helical reinforcement shall be secured
to the longitudinal reinforcements and the ends of such
transverse or helical reinforcement shall be properly
anchored.

(2) The diameter of transverse reinforcement shall be not less
than 6 mm or 1/4 of the diameter of the longitudinal reinforcement.
whichever is the greater dimension.

(3) The pitch of the transverse reinforcement shall not exceed-

(a) the least lateral dimension of the column.

(b)12 times the diameter of the smallest longitudinal rein-
forcement in that column; or

(c) 300 mm,

whichever is the least dimension.

(4)(a) Helical reinforcement shall be of regular formation
with the turns of the helix spaced evenly.

(b)Where an increased load on the column on account of
the helical reinforcement is allowed for under regula-
tion 143(1)(b), the pitch of the helical turns shall be-
(i) not more than 75 mm or of the core-diameter of
the column, whichever is the lesser dimension; and
(ii) not less than 25 mm or 3 times the diameter of the
helical reinforcement, whichever is the greater dimension.

(c)Where an increased load on the column on account of the
helical reinforcement is not allowed for the requirements
of paragraphs (2) and (3) shall be complied with.





123. (1) The diameter of a longitudinal reinforcement in a
reinforced concrete column shall be not less than 12 mm.

(2) The diameter of the main reinforcement in a reinforced
concrete slab shall be not less than 10 mm and that in a reinforced
concrete beam not less than 12 mm.

(3) The diameter of a reinforcement in reinforced concrete
(other than a longitudinal reinforcement in a column or a main
reinforcement in a beam or slab) and the diameter of a link, helix.
stirrup or the like, shall be not less than 6 mm.

(4) The diameter of reinforcement forming a fabric reinforce-
ment for the purpose of resisting tension in reinforced concrete shall
be not less than 5 mm.

124. (1) The distance between 2 reinforcements in reinforced
concrete shall be not less than-

(a) the diameter of either bar if their diameters are equal;

(b) the diameter of the larger bar if their diameters are
unequal; or

(c) 5 mm more than the greatest size of coarse aggregate
comprised in the concrete.

whichever is the greatest dimension.

(2)(a) When immersion vibrators are used, sufficient space
shall be provided to enable the vibrator to be inserted.

(b) The vertical distance between 2 horizontal main reinforce-
ments and the corresponding distance at right angles to 2
inclined main reinforcements shall be not less than 15 mm
or the maximum size of the coarse aggregate. whichever is
the greater.

(3)The provisions of paragraph (1) shall not apply at a splice.
except for the distance between pairs of lapped bars, nor to bars
transverse to one another.

(4)The pitch of main reinforcements in a reinforced concrete
solid slab shall not be more than 3 times the effective depth of that
slab.

(5) The pitch of distributing reinforcements in a reinforced
concrete solid slab shall be not more than 4 times the effective depth
of that slab.

125. (1 ) Where at any cross-section the shear stress. as calcu-
lated from the equation given in regulation 140(1). exceeds the
maximum permissible shear stress specified in regulation 116 the
whole shearing force shall be provided for by the tensile resistance of
shear reinforcement acting in proper combination with the compres-
sive resistance in the concrete:





Provided that-

(a)the magnitude of the shear stress so calculated shall not
exceed 4 times the maximum permissible shear stress for
the concrete alone; and

(b)the local bond stress in the main reinforcement calculated
in accordance with regulation 141Q)(a) does not exceed
the maximum permissible local bond stress specified in
regulation 116.

(2) Tensile reinforcement which is ipclined and carried through
a depth of beam equal to the arm of the resistance moment may also
act as shear reinforcement provided it is anchored sufficiently.

126. (1) A stirrup in reinforced concrete shall pass round, or
otherwise be adequately secured to the appropriate tensile rein-
forcement and each end of that stirrup shall be properly anchored.

(2) Where at any cross-secyion the shear stress. as calculated
from the equation given in regulation 140(1) does not exceed the
permissible shear stress for the concrete nominal stirrups shall be
provided at a spacing not exceeding the arm of the resistance
moment, or 450 mm, whichever is the smaller. Such nominal
stirrups shall be not less than 6 mm in diameter for beams not more
than 450 mm in depth and not less than 10 mm in diameter for
beams more than 450 mm in depth:

Provided that in any event the cross-sectional area of such
stirrups shall be not less than 0.15 per cent of the horizontal
cross-sectional area of the beam.

127. In a reinforced concrete solid slab spanning in one
direction-

(a)distributing reinforcement shall be provided at right-angles
to the main tensile reinforcement of that slab; and

(b)the area of reinforcement in each direction shall be not less
than 0.15 per cent of the gross cross-sectional area of the
concrete at right-angles to the direction of the reinforcement.

128. (1) Where compression reinforcement is required in a
beam, it shall be effectively anchored against buckling by stirrups at
points not further apart, measured from centre to centre, than 12
times the diameter of that compression reinforcement or 300 mm,
whichever is the smaller.

(2) Where the area of the compression reinforcement in a
beam exceeds 4 per cent of the cross-sectional area of the beam, any
steel in excess of that percentage shall be ignored in calculating the
resistance moment of the beam.





(3) For the purposes of paragraph (2) the cross-sectional area
of a rectangular beam shall be taken as the total depth multiplied by
the width and for a T or L beam shall be taken as the total depth
multiplied by the width of the rib.

129. (1) Where reinforced concrete walls are intended to carry
vertical loads. they shall. subject to the provisions of this regulation.
be in accordance with the appropriate provisions of regulations 114
to 123 for reinforced concrete columns-

(a)in the application of regulations 114 to 123 to reinforced
concrete walls, -effective height-, 'thickness- and -ver-
tical- shall respectively be substituted for---elTective column
length-. ---leastlateral dimension'* and -longitudinal-
wherever they occur in those regulations; and

(b)the provisions of regulation 122 relating to helical rein-
forcement shall not apply.

(2) In a reinforced concrete wall intended to carry vertical
loads-

(a)the aggregate cross-sectional area of the vertical reinforce-
merit shall be not less than 0.4 per cent of the gross
cross-sectional area of the wall.

(b)the aggregate cross-sectional area of the lateral reinforce-
ment shall be not less than 0.2 per cent of the gross
cross-sectional area of the wall;

(c)the diameter of a vertical reinforcement shall be not less
than 10 mm: and

(d)the distance between 2 vertical reinforcements shall not
exceed 300 mm.

(3) Where in a reinforced concrete wall. the stresses do not
exceed 75 per cent of the maximum permissible stresses specified in
regulation 116 -

(a)the provisions of regulation 122 relating to transverse
reinforcement shall not apply;

(b)the aggregate cross-sectional areas of the vertical and
lateral reinforcements shall each be not less than 0.2 per
cent of the gross cross-sectional area of the wall.

(4) The thickness of any load-bearing reinforced concrete wall
shall be not less than 125 mm.

(5) When tension occurs in a reinforced concrete wall.
adequate reinforcement shall be provided to resist such tension and
throughout the wall the reinforcement shall not in any section
thereof be less than 0.4 per cent of the gross cross-sectional area of
that section.





(6) Whenever the vertical reinforcement I's taken to assist in
resisting compression, transverse reinforcements in the form of
cross-ties shall be provided to prevent the vertical reinforcement
from buckling.

(7) The pitch of the tranverse reinforcement shall not exceed-

(a) 2 times the thickness of the reinforced concrete wall; or

(b)16 times the diameter of the smallest vertical reinforcement
in the wall; or

300 mm,

whichever is the least dimension.

(8) The effective width of a reinforced concrete wall subject to
concentrated loads, shall not exceed-

(a)the distance measured from centre to centre between
concentrated loads; or

(b) width of bearing plus 4 times the wall thickness on each
side of the concentrated load.

whichever is the smaller dimenson.

(9) A wall shall be effectively supported laterally by:

(a)horizontal reinforced concrete slabs of adequate thickness
to prevent buckling; or

(b)beams spaced with a clear spacing of not more than a
distance of 8 times the thickness of the wall. or

(c)reinforced concrete cross walls. where the wall is stiffened
by closely spaced cross walls such that the length of wall
between adjacent cross walls is less than the effective
height, the slenderness ratio shall be assumed to be the
ratio of this length to the wall thickness.

(10) In paragraphs (2) and (3) 'lateral reinforcement' means
reinforcements parallel to the length of the wall.

130. (1) Reinforcements shall not be connected by welding
without the approval of the Building Authority.

(2) When reinforcements are connected by welding. they shall
conform to the appropriate provisions of BS 693:1960. or BS
5135:1974.

131. (1) Computation of stresses shall accord with the laws of
mechanics and the recognized general principles relating to the
design of reinforced concrete.

(2) In the computation of stresses it shall be assumed that-





(a)both steel and concrete are elastic within the range of the
permissible stresses and the modular ratio is equal to 15,

(b) at any cross-section plane sections remain plane; and

(L.)all tensile stresses are taken by the reinforcement except
that the concrete may be assumed to resist diagonal
tension within the limits of shear stress specified for
concrete in regulation 116.

132. (1) Reinforced concrete members shall possess adequate
stiffness to prevent such deflexion or deformation as might impair
the strength or efficiency of the structure or produce cracks in
finishes or in partitions.

(2) For all normal cases it shall be assumed that the stiffness
will be satisfactory if-'

(a)in the case of members with steel stresses not more than
125 MPa, the ratio ofspan to overall depth does notexceed
the values, ~given in Table XXXII, and

(b)in the case of members with steel stresses greater than 125
MPa. the ratio of span to overall depth does not exceed 90
per cent of the values given in Table XXXII.

TABLE XXXII

Permissible values of ratio of spall to depth
of beams and slabs

(1) (2)

........BEAMS---..............Ratio of span to overall depth

Simply, supported ................................... 20

Continuous *** .****** ........... ** 25

Cantilever . ..................10

SLABS-
Spanning in 1 direction

(i) simply supported ........30

(ii) continuous ..............35

Spanning in 2 directions
(i) simply, supported ....................... 35
(ii) continuous ..............40

Cantilever ...................12

(3)(a) For the purposes of calculating bending moments in
continuous structures, the moment of inertia shall be
estimated by considering-





(i) the entire concrete section. ignoring the reinforce-
ment;
(ii) the entire concrete section, including the reinforce-
ment, on the basis of the modular ratio: or
(iii) t he compression area of the concrete section, com-
bined with the reinforcement on the basis of the modular
ratio.

(b)The same method shall be adopted for the beams and the
columns.

133. (1) The effective span of a beam or slab shall be taken
as-

(a) the distance between the centres of bearings~ or

(b)the clear distance between supports plus the effective depth
of the beam or slab.

whichever is the lesser.

(2) In paragraph (1)(b) 'effective depth' of a beam or slab is
the distance between the centre of tension and the edge of the
compression section.

134. (1) In T-beams the breadth of the flam-w assurned as
taking compression shall not exceed

(a)1/3 of the effective span of the T-beams:

(b)the distance between the centres of the ribs of the T-heams:
or

(c)the brandth of the rib plus 12 times the thickness of the
slab.

whichever is the least.

(2) In L-beams the breadth of the flange assumed as taking
compression shall not exceed-

(a) 1/6 of the effective span of the L-beams.


(b)the breadth of the rib plus ' of the clear distance between
ribs, or

(c) the breadth of the rib plus 4 times the thickness of the slab.

whichever is the least.

(3) When a part of a slab is considered as the flange of a
T-beam or L-beam-

(a) (i) the reinforcement in the slab transverse to the beam
shall cross the full breadth of the flange; and





(ii) where the slab is assumed to be spanning indepen-
dently in the same direction as the beam. such transverse
reinforcement shall be near the top surface of the slab: and

(b) the quantity of such reinforcement shall---
(i) be related to the shear stress in the slab produced by
its acting as the compression member of the T-beam or
L-beam; and

(ii) in no case be less than 0.3 per cent of the gross
cross-sectional area of the slab.

135. (1) Bending moments in beams and slabs shall be calcu-
lated for the effective span and all loading thereon.

(2) The bending moments to be provided for at a cross-section
of a continuous beam or slab shall be the maximum positive and
ncuative moments at such cross-section. allow ing in both cases. if so
desired. for the reduced moments due to the width of the supports.
for the following arrangements of super-imposed loadings---

(a) alternate spans loaded and all other spans unloaded:

(b) any 2 adjacent spans loaded and all other spans unloaded.

(3) Except where the approximate values for bending moments
assumed in regulation 136(1)(c) are used the negative moments at
the supports for any assumed arrangements of loading may each be
increased or decreased by not more than 15 per cent. in which case
the calculated simultaneous positive moments in the 2 adjacent
spans shall be decreased or increased. respectively by, the sanie
numerical value and the positive moments elsewhere in the span
adjusted accordingly.

136. (1) The bending moments in beams and slabs spanning in
1 direction shall be calculated on 1 of the following assumptions---

(a)beams shall be designed as members of a continuous
framework. with monolithic connexion between the beams
and columns, and the bending moments calculated taking
into account the resistance of the columns to bending.

(b) beams and slabs shall be designed as continuous over
supports and capable of free rotation about them. Never-
theless, where the supports to beams or slabs are mono-
lithic with them and stiff in relation to them, the beams or
slabs shall be designed with due regard to such stiffness: or

(c) unless more exact estimates are made. the bending moments
in uniformly loaded beams and slabs continuous over 3 or
more approximately equal spans shall be assumed to have
the values given in Table XXXIII.





TABLE XXXIII

Approximate values of bending moments in uniformly
loaded beams and slahs continuous ovre 3 or more
approximately equal spans


Nole: Wd is the total dead load per span.
Wx is the total superimposed load per an.
Spans may be considered as approximately equal when the shortest span
is not less than 85 per cent of the longest span.

(2) Notwithstanding the provisions of paragraph (1). where
beams are framed into external olumns they shall be designed to
resist bending moments in combination with the columns in con-
formity with regulation 143.

137. (1) The design of solid slabs spanning in 2 directions at
right angles shall be based on either of the methods given in
paragraphs (2) and (3).

(2) In order to estimate the bending moments in a slab
spanning in 2 directions at right angles. the slab shall be assumed to
act as a perfectly elastic thin plate, Poisson's ratio being assumed
equal to zero.
(3) Where, in the case of a simply supported slab. adequate
provision is not made to resist torsion at the corners of the slab and
to prevent the corners from lifting, the bending moments at mid-
span shall be assumed to have the values given by the following
equations:

Mx=Xxwlx2
My=Xywlx2

where -Mx and My are the bending moments at mid-span
on strips of unit width and spans lx and ly
respectively:
W is the total load per unit area:
ly is the length of the longer side;
lx is the length of the shorter side., and
Xx and Xy, are coefficients shown in Table XXXIV.





TABLE XXXIV

Bending moment coeficients for slabs spanning in 2 directions
at right angles simply supported on 4 side



(4) In the case of slabs restrained on 4 sides-

(a)where the corners of a slab are prevented from lifting and
adequate provision for torsion in accordance with sub-
paragraph (e) js made, the bending moments shall be
assumed to have the values given in sub-paragraph (e);
(b) slabs are considered as being divided in each direction into
middle strips and edge strips as shown in Diagram 1, the
middle strip having a width of 3/4 of the width of the slab
and each edge strip having a width of 1/8, of the width of the
slab, except that, for slabs for which the ratio of the sides
ly/lx exceeds 4.0, the middle strip in the short direction shall
be taken to have a width of ly-lx, and each edge strip a width
of lx/2

DIAGRAM 1

Division of slabs into
middle and edge strips

FOR SPAN lx FOR SPAN ly



(c)the maximum bending moments per unit width in the
middle strip of a slab shall be calculated by the following
equations:

Mx=Bxwlx2
My=Bywlx2

where-Mx and My are the maximum bending moment
on strips of unit width in the direction of
spans lx and ly respectively..
W is the total load per unit area:
ly is the length of the longer side;
lx is the length of the shorter side;
Bx and By are coefficients given in Table XXV.





TABLE XXXV

Bending moment coefficients for rectangular panels supported
on 4 sides with provision for torsion at corners

1 Short span coefficients Bx 10




l
Short span coefficients Bx 10





(d)No reinforcement parallel to the adjacent edges of the slab
need be inserted in the edge strips above that required to
comply with sub-paragraph (e) and regulations 124 and
127(b).

(e) (i) Torsion reinforcement shall be provided at the
corners of a slab except at corners contained by edges over
both of which the slab is continuous.
(ii) At corners contained by edges over neither of which
the slab is continuous, top and bottom reinforcement shall
be provided for torsion at the corner of the slabs. Both
top and bottom reinforcement shall consist of 2 layers of
bars placed parallel to the sides of the slab and extending in
these directions for a distance of 1/5 of the shorter span.
The area of the bars in each of the 4 layers. per unit width
of the slab, shall be 3/4 of the area equired for the maximum
positive moment in the slab.
(iii) At corners contained edges over only 1 of which
the slab is contiuous the torsional reinforcement may be
reduced to 1/2 of that required by sub-sub-paragraph (ii).
(iv) Any reinforcement provided for the purpose of
complying with other regulations may be included as
part of the reinforcement required to comply with this
paragraph.

Where a stab ends and there is monolithic connexion
between the slab and the supporting beam or wall, provi-
sion shall be made for the negative moments that may
occur in the slab at such support. The negative moment
to be assumed in these cases depends on the degree of fixity
afforded to the edge of the slab, but for general purposes it
may be taken as 2/3 of the moment given in Table XXXV for
the mid-span of the slab.

(5) The loads on the supporting beams for a 2-way rectangular
slab shall be assumed to be in accordance with Diagram 2.

DIAGRAM 2

Diagram showing the load
carried by supporting booms





138. (1) Allowance shall be made for the bending moments
due to concentrated loads, using methods based on the elastic
theory.

(2)(a) If a solid slab is simply supported on 2 opposite edges
and carries 1 or more concentrated loads in a line in the
direction of the span, it shall be designed to resist the
maximum bending moment caused by the loading system.
Such bending moment shall be assumed to be resisted by
an effective width of slab (measured parallel to the sup-
ports)equal to the sum ofthe load width and 2.4x (l - X/l)
where X is the distance from the nearer support to the
section under consideration and l is the span.

(b)Where the concentrated load is near an unsupported edge
of a solid slab the effective width shall not exceed the value
in sub-paragraph (a). nor 1/2 that value plus the distance of
the centre of the load from the unsupported edge as shown
in Diagram 3.
RAM 3

Effective width of solid stab
carrying a concentrated toad
near an unsupported edge


(3) Notwithstanding the provisions of regulation 127, distri-
bution reinforcement of not less than 0.3 per cent of the gross
cross-sectional area of the slab shall be provided over the full
effiective width resisting the bending moment due to the concen-
trated load.

139. When openings in floors or roofs are required such open-
ings shall be trimmed where necessary by special beams or reinforce-
ment so that the designed strength of the surrounding floor is not
impaired by the opening, due regard being paid to the possibility of
diagonal cracks developing at the corners of openings.

140. (1) The shear stress q at any cross-section in a reinforced
concrete beam or slab shall be calculated from the following
equation:





q= Q/bla

where-Q is the total shearing force across the section;
b is the breadth of a rectangular beam or the
breadth of the rib of a T-beam or L-beam; and
la is the arm of the resistance moment.

(2) (a) Where 2 or more types of shear reinforcement are used
in conjunction, the total shearing resistance of the beam
may be assumed to be the sum of the shearing resistances
computed for each type separately.

(b)The spacing of stirrups when required to resist shear-
(i) shall be not less than 8 times the diameter of the
stirrups or 75 mm, whichever is the greater; and
(ii) shall not exceed a distance equal to the arm of the
resistance moment.

The resistance to shear Q shall then be calculated from the
following equation:

Q=PstAwla/ S

where-Pst is the permissible tensile stress in the shear
reinforcement;
Aw is the cross-sectional area of the stirrup,
la is the arm of the resistance moment; and
S is ffie spacing of stirrups.

(c) (i) The resistance to shear at any section of a beam,
reinforced with inclined bars, may be calculated on the
assumption that the inclined bars from the tension mem-
bers of 1 or more single systems of lattice girders in which
the concrete forms the compression members.
(ii) The shear resistance at any vertical section shall
then be taken as the sum of the vertical components of the
tension and compression forces cut by the section.
(iii) Care must be taken that such assumptions do not
involve greater stresses in the horizontal bars than the
permissible stresses.

a distance to the end of the bar such that the average bond
stress does not exceed the permissible average bond stress
given in regulation 116.

(b)The length measured from such section shall be not less
than-

the bar diameter x the tensile stress in the bear
4 times the permissible average bond stress.





(c)The bar shall extend at least 12 bar diameters beyond the
point at which it is no longer required to resist stress.

(d)For the purposes of this paragraph, the length of the bar so
determined may have deducted from it a length equivalent
to the value of the hook as given in paragraph (5) but no
deduction shall then be made for the length of the bar
contained in the hook.

(2) (a) The local bond stress calculated from the formula-

Q/lao

where- Q is the tal she force across the section;
la is the arm of the resistance moment; and
o is the sum the perimeters of the bars in the
tensile reinforcement,

shall not at any point exceed the permissible local bond
stress given in regulation 116.

(b)In members of variable depth the effect of the change in
depth shall be taken into account in calculating the bond
stress.

(3) Hooks and other anchorages of reinforcement shall be
of such form, dimensions and arrangement as will ensure their
adequacy without over-stressing the concrete or other anchorage
material.

(4)(a) A hook at the end of a mild steel bar shall be of the
form indicated in Diagram 4 with an internal radius of the
bend not less than 2 times the diameter of the bar, and a
length of straight bar beyond the end of the curve of at
least 4 times the diameter of the bar, except that where the
hook fits over a main reinforcing or other adequate anchor
bar, the radius of the bend may be reduced to that of the
main reinforcing or anchor bar.

DIAGRAM 4

Standard book for mild steel bars





(b) Where hooks are formed in high-yield bars---
(i) the internal radius of the bend shall be at least 3
times the diameter of the bar; and
(ii) the length of straight bar beyond the end of the
curve shall be at least 4 times the diameter of the bar.

(5) A bend in a reinforcement bar shall be assumed to have an
anchorage value equivalent to a length of bar equal to 4 times the
diameter of the bar for each 45 degrees through which the bar is
bent:

Provided that-

(a)the radius of the bend shall be not less than 2 times the
diameter of mild steel bars, or 3 times the diameter of
high-yield bars;
(b) the length of the straight part of the bar be ond the end of
the curve shall be at least 4 times the diameter of the bar;
and

(c)whatever be the angle through which the bar is bent. the
assumed anchorage value shall not be taken as more than
equivalent to a length of bar equal to 16 times the diameter
of the bar.

(6) In bends in reinforcing bars, the local stress on the concrete
shall not exceed 3 times the value permitted in regulation 116 for the
concrete in direct compression.

(7) Notwithstanding any of the provisions of paragraphs (1)
to (6), in the case of stir ups and transverse ties, complete bond
length and anchorage shall be deemed to have been provided when
the bar is-

(a) (i) bent through an angle of at least 90 degrees round a
bar of at least its own diameter, and
(ii) the stirrup or tie is continued beyond the end of the
curve for a length of at least 8 bar diameters: or

(b) (i) bent through an angle of 180 degrees; and
(ii) the stirrup or tie is continued beyond the end of the
curve for a length of at least 4 bar diameters.

(8)(a) A bar in compression shall extend from any section
for a distance such that the average bond stress does not
exceed. the permissible average bond stress given In regula-
tion 116 by more than 25 pet. cent.

(b)The length measured from such section shall be not less
than-

the bar diameter x the compressive stress in the bar
5 times the permissible average bond stress,





(c)The bar shall extend at least 12 bar diameters beyond the
point at which it is no longer required to resist stress.

(9)(a) Laps in bars in any member shall be staggered
wherever practicable.

(b) The length of lap in bars in tension shall be not less than-

the bar diameter x the tensile stress in the bar : or
4 times the permissible average bond stress

30 bar diameters,

whichever is the greater.

(c)The length of lap in bars in compression shall be not less
than-

the bar diameter x the compressive stress in the bar : or
5 times the permissible average bond stress

24 bar diameters,

whichever is the greater.

(10)(a) In the case of deformed bars, the bond stresses shall
not exceed those permitted in regulation 116 by more than
25 per cent

(b)For the purpose of this paragraph. a bar is deformed if its
bond strength exceeds that of a plain round bar by 25 per
cent or more

(11) All bent up bars acting as shear reinforcements shall be
fully anchored in both flanges of the beam, the anchorage length
being measured from the end of the sloping portion of the bar.

142. (1) In this regulation, a floor or roof of ribbed and hollow
block construction means a floor or roof which consists of a series of
reinforced concrete ribs cast-in-situ-

(a)between blocks which remain part of the completed floor
or roof, or

(b) on forms which may be removed after the concrete has set.

(2) Blocks and forms shall be of suitable material which will
retain its shape and dimensions and is strong enough to support the
concrete when placed.

(3) The tops of the ribs shall be connected by a topping of
concrete, of the same quality as the concrete used for the ribs and,
cast-in-situ, over the blocks or forms.

(4) The blocks shall be neglected in determining the bending
and shearing resistance of hollow block construction.





(5) Subject to the provisions of Part XVI (Fire Resisting
Construction), the thickness of topping. after allowance has been
made for the effect of wear if necessary. shall be not less than 50 mm
or A the clear distance between the ribs. whichever is the greater.
10

(6) (a) The width of the rib shall be not less than 75 mm.

(b)The depth, excluding any topping, shall be not more than 3
times the width.

(c)The spacing shall be not more than 750 mm measured from
centre to centre.

(7) At least 50 per cent of the total positive reinforcement in
ribs shall be carried through at the bottom on to the bearin and
effectively anchored.

(8) For the purpose of determining the positive reinforcement
in the span, floors continuous over soports may be treated as
simply supported, in which case, negative reinforcement shall-

(a) be provided over the support to prevent cracking.

(b) have a cross-sectional are of not less than 1/4 of the positive
reinforcement in the mi dle of the adjoining bays. and

(c.) extend at least 1/5 of th clear spans into the adjoining bays.

(9) Notwithstanding regulation 115 (minimum cover to rein-
forcement) and subject to the provisions of Part XVII (Fire
Resisting Construction), cover to reinforcement shall be not less
than 20 mm or the diameter of the bar, whichever is the greater,
exclusive of any finishing materials.

(10) Notwithstanding regulations 123, 124 and 125. the topping
slab shall be reinforced with-

(a)main reinforcement at right angles to the ribs, required for
flexure, but not less than 0.3 pep. cent of the gross cross-
sectional area of the concrete and spaced at a distance not
more than 4 times the total thickness of the topping, and

(b)distribution reinforcement at right angles to the main
reinforcement of an amount not less than 0. 15 per cent of
the gross cross-sectional area of the concrete and spaced at
a distance not more than 5 times the total thickness of the
topping:


Provided that the diameter of the main reinforcement shall be
not less than 6 mm where bars are used or 5 mm where fabric is used.

(11) Where blocks are used in between cast-in-situ ribs as part
of the completed floor or roof, they shall not be placed within 75 mm
from the walls or beams at right angles or parallel to the ribs.





(12) In floor or roof systems where the ribs run in one direction
only, stiffeners of minimum 75 mm width between ribs for the full
depth of the rib shall be provided for clear length of rib greater than
4 m and at intervals not exceeding 4 m.

forced with longitudinal bars and lateral ties shall not
exceed that given by the following equation:

Po=pccAc+pscAsc

where-pcc is the permissible stress for the concrete in
direct compression;
Ac is the cross-sectional area of concrete exclud-
ing reInfol cing steel;
Psc is the permissible compressive stress for
column bars; and
Asc is the cross-sectional area of the longitudinal
steel.

(b)Where helical reinforcement is used, the permissible axial
load Po on a column shall not exceed that given by the
equation in sub-paragraph (a). or the following equation.
whichever is the greater:

Po=PccAk+P Asc + 185Ab
where-Ak is the cross-sectional area of concrete in the
core excluding the area of longitudinal rein-
forcement; and
Ab is the equivalent area of helical reinforcement
(volume of helix per unit length of the
column), and
Pcc Ak + 185Ab shall not exceed 0.5uwAc where
uw is the works resistance to crushing of the
concrete at 28 days.

(c)The permissible combination of direct load and bending
moment to which a column may be subjected shall be
determined on the basis of the elastic theory, with a
modular ratio of 15 and the permissible stresses in bending
given in regulations 116 and 117.

(d)The load on a column subject to both direct load and
bending moment shall not exceed that permissible for an
axially load column.

(c) The permissible load on a reinforced concrete column,
having a ratio of effective length to least lateral dimension
between 15 and 36, shall not exceed the appropriate
permissible load in sub-paragraph (a), (b), (c) or (d)
multiplied by the coefficient appropriate for each ratio of





effective column length to least lateral dimension shown in
Table XXX. When, in a column having helical reinforce-
ment, the permissible load is based on the core area, the
least lateral dimension shall be taken as the diameter of the
core.

(2)(a) Bending moments in internal columns supporting an
approximately symmetrical arrangement of beams and
loading shall not be required to be calculated except in the
case of flat slab construction.

(b)Bending moments in external columns and in internal
columns supporting an arrangement of beams and loading
not approximately symmetrical shall be calculated and
provided for. The expression given in Table XXXVI shall
be used for estimating moments-,

TABLE XXXVI

3 4

1 2 Moments for
Moments for frames of 2 or
frames of 1 bay. more bays


Note:-
(1) Me is the bending moment at the end of the beam framing into the
column, assuming fixity at both ends of the beam;
Mes is the maximum difference between the moments at the ends of the 2
beams framing into opposite sides of the column. each calculated on
the assumption that the ends of the beams are fixed and assuming
one of the beams unloaded;
Kb is the stiffness of the beam;
Kbl is the stiffness of the beam on 1 side of the column:
Kb2 isthe stiffness of the beam on the other side of the column:
Kl is the stiffness of the lower column:
Ku is the stiffness of the upper column.

(2)The stiffness of a member shall be obtained by dividing the moment of
inertia of a cross-section by the length of the member. provided that the
member is of constant cross-section throughout its length.





144. (1) The bending moments at any section ofa footing fora
reinforced concrete column or wall shall be taken to be the moment
of the forces over the entire area on 1 side of the section. The
critical section for bending in the footing shall be taken at the face of
the column or the wall.

(2)(a) Subject to sub-paragraph (b) the reinforcement pro-
vided to resist the bending moments specified in paragraph
(1) shall be distributed uniformly across the full width of
the section.

(b)In rectangular flootings for columns, the reinforcement
parallel to the hort edge should be more closely spaced
near the column.

(3) The critical sections for shear shall be taken to be at a
distance from the column face equal to the efFective depth of the
footing.

(4) The critical section for local bond stress shall be taken to
be the same section as the critical section for bending moment at the
face of the column or wall.

145. Flat slabs may be designed-

(a) as continuous frames analysed by the elastic theory in the
manner described in regulation 155; or

(b) by the empirical method described in regulation 156,
and shall comply with regulations 146 to 154.

146. (1) In regulations 147 to 156---

'flat slab' means a reinforced concrete slab with or without drops,
supp ted, generally without beams. by columns with or with-
out flared column heads;

'panel' means the rectangular part of a flat slab enclosed by the
Centre lines joining 4 adjacent columns,

'drop' means the part of a flat slab which is thickened throughout
an area surrounding the column or column head; and

'column head' means an enlargement at the top of a column which
is designed and built to act monolithically with the column and
flat slab.

(2) In regulations 147 to 156-
L1 is the length of the panel in the direction of the span.
L2 is the width of the panel at right angles to the span;
L is the average of L, and L2;
D is the diameter of the column head or column, where no
column head is provided;
ts is the thickness of the slab;
td is the thickness of the drop; and
w is the total load per unit area on the panel.





147. Flat slab panels shall be assumed to be divided into---

(a)a middle strip which shall run the full length of the panel
symmetrical about the centre line of the panel and ' the
width of the panel,

(b)a column strip which shall run the full length of the panel
and consist of 2 adjacent quarter panel widths, 1 on each
side of the column centre line,

as shown in Diagram 5.

DIAGRAM 5
Division of flat sab panels
into column and middle strips



148. The minimum thickness t2 of a flat slab shall be not less
than-

(a) 125 mm;

(b) L/32 for end panels without drops,


L/36 for fully continuous interior panels without drops and
for end panels with drops;

(d ) L/40 for fully continuous interior panels with drops,

whichever is the greatest.

149. (1) The critical sections for shear shall be assumed to be-

(a)at a distance from the column head or, when no column
head is provided, from the column of 1/2 the thickness of the
drop, or, where no drop is provided, 1/2 the thickness of the
slab; and





(b) at a distance from the drop of ' the thickness of the slab,

as shown in Diagrams 6, 7 and 8.

(2) The shearing stresses at the critical sections shall not
exceed the permissible values specified in regulation 116.

150. (1) Columns supporting flat slabs shall not be less than
300 mm in diameter.

(2) When column heads are provided, the interior column
heads and such part of the exterior column heads as will lie within
the building shall satisfy the following requirement-

(a)the angle of slope of the column head shall not exceed 45-
from the vertical;

(b)the diameter (D) of the column head shall be measured at a
distance 40 mm below the slab or drop; and

(c) the diameter (D) shall not exceed 4
as shown in iagrams 7 and 8.

(3) For the purposes of paragraph (2), where column and
column ad are not circular in cross-section the term diameter (D)
shall be cemed to mean the diameter of the largest circle which can
be draw within the actual section at a distance of 40 mm below the
slab or rop.

(4 No part of any column head which lies outside the en-
velope described in paragraph (2) shall be considered for structural
purposes.
DIAGRAM 6

Critical section for shearing stress in flat slabs
without drop and column without column hood






DIAGRAM 7

Critical section for shearing stress in flat
slabs without drop


DIAGRAM 8.

Critical sections for shearing stresses in
flat slabs with drop


151. (1) An opening shall not encroach on a column head or a
drop.

(2) Except where the aggregate length or width of openings
does not exceed any of the following-

(a)in the area common to 2 middle strips, 0.4L measured
parallel to the centre line;

(b) in the area common to a middle strip and a column strip, 1/4
the width of the strip;





(e)in the area common to 2 column strips, 1/10 of the width of
the strip,

openings shall be completely framed on all sides with beams capable
of carrying the loads to the columns.

(3) When framing capale of carrying the loads to the
columns is not provided for openings within the limitations of
paragraph (2), the remaining portions of the slab or strip shall be
designed to resist the total negative or positive moments and shear
so that the strength of the slab as a whole is not impaired by the
openings.

152. (1) Drops hall be rectangular in plan.

(2) The thickness of a drop shall be not less than 1 1/4, nor more
than 1 1/2, times the thickness of the slab.


(3) The overall width of a drop shall be not less than 1/3 the
panel width nor more than 1/2 the panel width in that direction.

(4) For exterior panels the width of the drop at right angles to
the discontinuous edge and measured from the column centre line
shall be 1/2 the width of drop for interior panels.

153. (1) The spacing of reinforcement at critical sections shall
not exceed 2 times the effective depth except in those portions of the
slab which may be of cellular or ribbed construction.

(2) When the drop, if provided, is less than the full width of
the column strip, the reinforcement in the thinner part of the column
strip shall be of the same diameter at the same spacing as the
reinforcement in the middle strip and the remainder of the reinforce
ment required to resist the maximum bending moments in the
column srip shall be placed within the width of the drop.

(3) When the diameter of the column head is less than 2 times
the diameter of the column, of the reinforcement required to resist
the negative moment in the column strip shall be placed in 1 the
width of the column strip and symmetrical about the line joining the
column centres.

(4) At all discontinuous edges all reinforcement shall extend to
within 75 mm of the edge of the panel and shall be hooked around a
bar of its own or greater diameter or shall be properly anchored in
the edge beam, if any.

(5) Splices-

(a) shall not be made at sections of maximum stress; and

(b) where required, should be staggered.





154. Where the slab is supported by a marginal beam of depth
greater than 1 1/2 times the thickness of the slabs, or by a wall-

(a)the load to be carried by the beam or wall shall be all loads
carried directly on the beam or wall plus a uniformly
distributed load equal to of the total load on the slab;

(b) the bending moment in the 1/2 column strip adjacent and

parallel to the beam or wall shall be 1/4 of the moments
specified in regulation 155 or 156.

155. Where flat slabs are designed as continuous frames and
analysed by the elastic theory-

(a)the structure shall be divided longitudinally and trans-
versely into frames each consisting of a row of columns
and a strip of slab bounded by the centre lines of the panels
on each side of the row of columns. both longitudinal and
transverse frames each being designed for the full load on
the floor area;

(b)each frame may be analysed in its entirety, or each strip of
floor or roof may be analysed separately assuming the
columns to be fixed at the floor above and below,

(c)the spans used in the analysis shall be to the centre lines of
supports except for a slab supported on a wall when the
span shall be taken to the face of the wall plus the depth
of the stab;

(d)the moment of inertia of the slab or column shall be
assumed to be that of the gross cross-section of the
concrete, variation of moment of inertia along the axes of
columns or slabs being taken into account;

(e)the joints between column and slab shall be considered
rigid and this rigidity (infinite moment of inertia) shall
extend in the slab from the column centre line to the edge
of the column or column head and in the column from the
top of the slab to the bottom of the column head if
provided;

(f) the maximum moments shall be calculated for the follow-
ing arrangement of the imposed loads-
(i) where alternate spans are loaded and all other spans
unloaded; and
(ii) where any 2 adjacent spans are loaded and all other
spans unloaded;

(g)the slab shall be designed for the bending moments as
determined in sub-paragraph (f), which shall be dis-
tributed between the column strip and middle strip in
accordance with Table XXXVII;





TABLE XXXVII

Distribution expressed as percentage of
total negative or positive moments

2 3

1

Column strip Middle strip

Negative moments ......75 25
Positive moments ......55 45

Note: Provision need not be made for greater negative moments than those at the
critical sections for shear immediately adjacent to the column as defined in
regulation 149(1)(a);

Provided that the sum of the Maximum Positive
bending moment and the average of the maximum nCga-
tive bending moments for the whole panel width used in
the design of any 1 span shall be not less than:
wL2/10 [L1 -2D/3]2

(i) where w is the total load per unit area on the panel;
(ii) where the diameters of the columns or column
heads supporting the panel are not equal, D shall be taken
as the average of the 2 diameters;

(h) columns shall be designed to resist the combination of
bending moment and direct load consistent therewith
which produces the greatest stresses in the column.

156. (1) Flat slabs designed by the empirical method shall
comply with the provisions of this regulation.

(2) The slabs shall comprise rectangular panels and there shall
be at least 3 continuous panels in both directions.

(3) The ratio of the length of a slab to its width shall not
exceed 4:3.

(4) The length or width of any 2 adjacent panels shall not
diffier by more than 10 per cent of the greater length or width. End
spans may be shorter but not longer than adjacent interior panels.

(5) Where adjacent spans differ the length of the longer span
shall be used in calculating the negative bending moments between
the 2 panels.

(6) For fully continuous interior panels the critical sections for
bending moment are-

(a) for positive moment, along the centre lines of the panels,





(b)for negative moments, along lines joining the centres of the
columns and around the perimeter of the column heads.

(7) The total bending moment in each direction for a panel
shall be:

Mo = wL2/10 [ L1 - 2D/3]2

and shall be distributed between the column strips and middle strip
by the percentage specified in Table XXX VIII.

TABLE XXXVIII

Distribution of bending moments in panels of flat
slabs designed by the empirical Ineihod

Distribution of moments
expressed as a percentage
of Mo

(8)(a) Slabs shall be reinforced in 2 directions and the
reinforcement shall be so disposed that each strip is rein-
forced over its full width.

(b)In each strip not less than 50 per cent of the positive
reinforcement shall extend in the lower part of the slab to
not less than 0.125L from the line joining the centres of the
columns.





(c)Not more than 50 per cent of the positive reinforcement
may be bent up at a distance of not less than 0.25L from
the centre line of the panel.
(d)Not less than 50 per cent of the negative reinforcement
shall extend not less than 0. 3L beyond the line joining the
centres of the columns.
(e)Negative reinforcement in the top of the slab shall not stop
or be bent down at a distance of less than 0.2L from the line
joining the centres of the columns as shown in Diagram 9.

(9)(a) Internal columns shall be designed to resist 50 percent
of the maximum negative moment in the column strip.
(b)External columns shall be designed to resist 90 per cent of
the maximum negative moment in the column strip.
(c)These moments shall be apportioned between the upper
and lower columns in proportion to their stiffnesses.
(d)When external columns carry portions of the floors and
walls as a cantilevered load the specified column moments
may be reduced by the moment due to dead load only on
the cantilever.

DIAGRAM 9

Details of Reinforcement


157. (1) Subject to the provisions of regulations 118 and 120
the compressive, shear and bond stresses in reinforced concrete
constructed of special or designed mixes shall not exceed the
maximum permissible stresses specified in Tables XXXIX and XL
for the appropriate mix.





(2) For the purpose of Tables XXXIX and XL, uw is the
works resistance to crushing of the concrete when tested in
accordance with the First Schedule within 28 days after mixing.

TABLE XXXIX

Maximum permissible conipressive stresses for special mixes
and designed mixes in MPa

Maximum permissible compressive stress

1 2 3

direct due to bending


Special mixes uw/4 but not more than 8.5 uw/3 but not more than 11

Designed mixes Uw/3.65 but not more than 11 uw/2.73 but not more than 15

TABLE XL

Maximum permissible shear and bond stresses for special and designed mixes in MPa






(3) Before adopting the higher stresses permitted for designed
mixes the registered structural engineer responsible for the design
shall give due consideration to the exactness of the method of design,
deflexions, site conditions which may affect adversely the control or
proper curing of the concrete, and such other factors as might
influence his selection of the appropriate strength of concrete for
the work.

(4) The requirements of regulation 116(2) shall apply to
special and designed mixes subject to the maximum permissible
stresses specified in Table XXXIX.

158. (1) Subject to regulation 118, the upper limit for the
maximum permissi e stresses specified in Table XXIX may be
increased to those specified in Table XLI.

TABLE XLI

Maximum permissible stresses in reinforcement in reinforced concrere






(2) The maximum stress specified in regulation 120(h) may be
increased from 185 to 230 MPa.

(3) In slender beams to which regulation 116(2) applies the
stress in any compression steel shall not exceed the permissible stress
specified in Table XLI for compression in main reinforcement
multiplied by the appropriate coefficient specified in Table XXVIII.

(4) For the purposes of this regulation the modular ratio shall
be taken as 15.

159. The provisions of regulation 118 shall apply to columns of
special and designed mixes subject to the maximum permissible
stresses specified in Table XXXII.

160. (1) It shall be assumed for all normal cases that the
stiffness of members will be satisfactory:

Provided that-

(a)where either the stress in the reinforcement exceeds 140
MPa or the stress in the concrete exceeds 10 M Pa the ratio
of span to overall depth does not exceed 90 per cent of the
value given in Table XXXII;

(b)where both the stress in the reinforcement exceeds 140
MPa and the stress in the concrete exceeds 10 MPa the
ratio of span to overall depth does not exceed 85 per cent
of the values given in Table XXXII.

(2) In the case of members designed by the load factor method,
the limiting stresses for the purposes of paragraph (])(a) and (b) shall
be the stresses at working loads.

161. (1) Subject to the following provisions of this regulation,
reinforced concrete members may be designed to have a load factor
of not less than 1.8 against crushing of the concrete and against
yielding of the steel.

(2) For the purposes of paragraph (1) the resistance to crush-
ing of the concrete in the member shall, for beams and slabs, be
assumed to be-

(a)not more than 3/5 of the specified resistance to crushing of
the concrete for the works test at 28 days-
(i) for ordinary concretes in accordance with Table IV;
(ii) for Quality A concretes in accordance with Table V;
and
(iii) for special concrete mixes in accordance with Table
VI; and

(b) not more than 2/3 of the specified resistance to crushing of
the concrete for the works test at 28 days for designed
concrete mixes in accordance with Table VI.





(3) For the purposes of paragraph (1) the resistance to crush-
ing of the concrete in the member shall, for columns, be assumed
to be-

(a)not more than 0.68 times the specified resistance to crush-
ing of the concrete for the works test at 28 days-
(i) for ordinary concretes in accordance with Table IV;
(ii) for Quality A concretes in accordance with Table V;
and
(iii) for special concrete mixes in accordance with
Table VI; and

(b)not more than 0.76 times the specified resistance to crush-
ing of the concrete for the works test at 28 days for
designed concrete mixes in accordance with Table VI.

(4) For the purposes of paragraph (1)-

(a) the maximum stress in the concrete at failure shall be taken
as not more than 2/3 of its resistance to crushing as assumed
in paragraph (2) or (3) and considered as constant over the
depth of th the compression zone, which depth in the case of
beams and slabs shall not be taken as greater than 1 the
effective depth of the member,
(b) the yield point of the reinforcement shall be taken as not
greater an 1.8 times the appropriate maximum permis-
sible stress specified in Table XXIX and regulation 158.

(5) Paragraph (1) shall apply only where the stresses in the
members at working loads are not such as to cause excessive
cracking ore cessive deflexions.

162. (1) For a beam to which regulation 116(2) applies designed
by the load factor method, the maximum permissible load shall be
the maximum load calculated as for a normal beam and multiplied
by the coefficient specified in Table XXVIII for the appropriate
slenderness ratio.

(2) For a column to which regulation 118(2) applies designed
by the load factor method, the maximum permissible load, or
combination of direct load and bending moment, shall not exceed
the maximum load, or combination of direct load and bending
moment, calculated as for a short column and multiplied by the
coefficient specified in Table XXX for the appropriate ratio of
effective column length to least lateral dimension.

163. For beams and solid slabs of rectangular cross-section
without compressive reinforcement and for qualities of concrete and
steel within the range permitted by these regulations, the require-
ments of regulation 161 may be deemed to be satisfied if the resistance
moment (Mr) (corresponding to the working loads) is assumed to be
the lesser of the 2 values calculated from the following 2 equations:





(1) based on the tensile reinforcement,

Mr = Astpstla,
(2) based on the resistance to crushing of the concrete in
compression,
Mr = Pcb/4 bd1 2

where-la is the lever arm, which may be taken as
d1- 3Astpst/ 4bpcb

Ast is the area of tensile reinforcement,
Pst is the permissible tensile stress in the rein-
forcement;
Pc is the permissible compressive stress in the
concrete in /bending;
b is the breadth of the section., and
d1 is the effective depth to the tensile rein-
forcement;

(3) where it is necessary/ior the resistance moment to exceed

Pcb/4 bd12, compressive reinforcement should be provided
so that

M=Pcb/4 bd12 + AscPsc (d1 - d2)

where-Asc is the area of compressive reinforcement;
psc is the permissible compressive stress in the
steel, or
380(1 - d2/dn) M Pa,

whichever is the lesser,
dn is the depth of the concrete in compression.,
and
d2 is the depth to the compressive reinforce-
ment.

The area of tensile reinforcement shall be such that the stress in
the steel does not exceed the permissible stress.

164. (1) The resistance moment when compressive reinforce-
ent is not provided may be assumed to be the lesser of the 2 values
alculated from the following equations:

(a) based on the tensile reinforcement,

Mr = Astpst (d1 - ds/2)






(b)based on the resistance to crushing of the concrete in
compression.

Mr = pcb bd12

where ds is the depth of slab forming the flange and the factor
has the values given in Table XLII.

TABLE XLII

Values of for computing resistance nionient based on the resistance
to crushing of the concrete in compression

Values of for d1/ds

1 2 3 4 5 6 7
b/br 2 or less 3 4 5 6
1 0.25 0.25 0.25 0.25 0.25 0.25
2 0.25 0.22 0.20 0.185 0.175 0.125
4 0.25 0.20 0.17 0.15 0.14 0.062
6 0.25 0. l95 0.165 0.14 0.125 0.042
8 0.25 0.19 0.16 0.135 0.12 0.031
0.25 185 0.145 0.12 0.10 0

Note: br is the width of the rib.

(2) Where it is necessary for the resistance moment to exceed
pcb bd1 2 compressive reinforcement should be provided so that:

Mr = pcb bd1 2 + Asc psc(d1 - d2)

and the area of tensile reinforcement should be such that the stress in
this steel does not exceed the permissible stress.

(3) For in ermediate values of b/br and d1/ds, the value of can
be calculated from the following formula:

= br/4b + 1/3 [1-br/b][2ds/d1 - (ds/d)2]

165. (1) For columns of rectangular section with symmetrical
reinforcement, the section should be assumed to be controlled by
compression when the load exceeds Pb given by the following
equation:

Pb = pccbd1 X - Asc(pst - psc)

where pcc is the permissible stress for the concrete in direct
compression;
b is the breadth of the column.
d1 is the effective depth to the tensile reinforcement:
Asc is the area of the compressive reinforcement:
which for the conditions of bending to which
the above equation applies is equal to 1/2 of the
total area of reinforcement in the column;





psc and pst are the permissible stresses in the reinforcement
for compression and tension. respectively, and
X = 585/ 690 + 1.8 Pst

where cold worked reinforcement is used, the denominator
in the formula for X should be increased to:

690 + 375Pst x 103/ Es

in which Es is the secant modulus of elasticity of the steel at
a stress of 1.8Pst,

At the load Pb the corresponding eccentricity of load eh
relative to the centre of the section is given by the following
equation:

Pb (eb + d1-d2/2) = pcc bd1 2 X(1-1/2X) + AscPsc(d1-d2)

where d2 is the depth to the compressive reinforcement.

(2) When the section is controlled by compression. the permis-
sible load (P) on the column is related to the permissible load (P,)
for an axially loaded column, as given in regulation 143(])(a), and
the eccentricity (e) of the load (P) relative to the centre of the
section, according to the following equation:

P=Po/1 + [Po/Pb - 1] e/eb

(3) When h applied load is less than Pb the section is
controlled by tension and the permissible load is given by the
following

P= pcc bd (0.5 - e/d - Y)

+ (0.5 - e/d - Y)2 + psc/pcc (d1 - d2/d) + Y(2d1/d - Y)

where- Y = r/2 [ Pst - Psc/Pcc]

r = total area of reinforcement/bd; and

d is the overall depth of the column section.





PART XIII

WHARVES, PIERS AND SEA-WALLS

166. Every sea-wall, breakwater, jetty, mole, quay, wharf or
pier shall be designed and constructed to the satisfaction of the
Building Authority.

PAR XIV

RETNING WALLS

167. (1) Retaining walls may be constructed of masonry, brick-
work, or plain or reinfored concrete.

(2) Retaining walls shall be so designed and constructed as to
support safely the ground they retain and any loads and pressures
from any surcharge, traffic and footings of nearby structures on top
or at the back of the walls and any water pressures that may be im-
posed on the back face and on the base of the walls, and to provide
a safety factor of-
(a) 2.0 against overturning; and

(b) 1.5 against sliding depending on friction on ground only.
or 2.0 against sliding if passive ground resistance is added
to counteract sliding.

168. (1) A foundation of concrete shall be provided on solid,
undisturbed ground or on piles.

(2) Such foundation shall extend for the full thickness at the
base of the retaining wall, and shall be so designed that the
resultant of all forces acting on the wall shall be within the middle
third of the foundation, or if on piled foundation shall cause no
tension in any pile.

169. Retaining walls constructed of brickwork shall be properly
bonded and built solid throughout in cement mortar.

170. Retaining walls constructed of masonry may be built in
cement mortar or dry. In either case the wall shall be properly
bonded .

171. (1) Retaining walls constructed of brickwork or masonry
exceeding 4 m in height shall be provided with 1 or more bond
courses of concrete, in no respect inferior to Grade III and at least
300mm in depth;

Provided that bond courses of reinforced concrete may be less
than 300 mm in depth.

(2) The distance between the foundation and the first of such
bond courses and the distance between any 2 adjacent bond courses
shall not exceed 2 m measured vertically.





172. (1) A weep hole, with an internal diameter of not less than
75 mm, shall be provided to every 3 m2 of the face of every retaining
wall:

Provided that weep holes may be omitted in retaining walls-

(a) constructed of masonry built dry; or

(b)designed to withstand maximum potential hydraulic pres-
sure; or

(e)with adequate subsoil drainage behind such retaining wall
to carry away subsoil water.

(2) Where on or after the date* on which the Building (Con-
struction) (Amendment) Regulations 1981 come into operation a
drainage system is incorporated in a retaining wall to reduce any
water pressures that may be imposed on the back face and on the
base of the retaining wall, such drainage system shall be designed
and constructed so as not to be rendered ineffective during service by
the penetration of soil or due to any other cause.

173. (1) Every retaining wall shall be provided with a proper
coping of concrete or such other materials as the Building Authority
may approve.

(2)(a) Where the ground at the top of any retaining wall or
portion of the wall is accessible and is more than 600 mm
above the ground level at the foot of the walls or portion of
wall, parapet walls or railings not less than 1 100 mm in
height from top of coping level. shall be provided.

(b)Such parapet walls or railings shall be so constructed as to
inhibit-
(i) climbing; and
(ii) the passage of articles more than 100 mm in their
smallest dimension.

(c)The lowermost 150 mm of such parapet walls or railings
shall be built solid.

174. Adequate channels laid to suitable gradients, or paving in
accordance with the provisions of regulation 41 shall be formed at
the top and toe of every retaining wall to carry away stormwater.
seepage, or other surface water.

PART XV

WELLS

175. No well shall be sunk or reopened without the permission
of the Building Authority.





176. No well shall be sunk in the vicinity of any septic tank,
cesspool, sewage sump or in any foul ground and no well shall be
excavated near any foundations.

177. (1) Wells may be excavated or bored and shall be of
sufficient diameter and depth to provide an adequate water supply.

(2) For the purposes of this regulation, a supply of water shall
be adequate if in the opinion of the Building Authority the yield
of water from such well during the period from 1 December to
30 April next succeeding, as ascertained and certified in accordance
with this regulation, wuld be sufficient in all respects for all the
purposes for which the well is to be used.

(3) For the purpose of this regulation, the yield of water from
a well shall be ascertained by the authorized person in a manner and
by a method approved by the Building Authority-

(a) during the first such period as is referred to in paragraph
(2) after the first consent to the commencement of the
building works is given by the Building Authority in
respect of the building for which the well is required, or if
such first consent is given during such a period then during
such period. or

(b) if the Building Authority so directs. during any such period
as is referred to in paragraph (2) after the first consent to
the commencement of the building works is given by the
Building Authority in respect of the building for which the
well is required.

(4) The yield of water from the well ascertained in accordance
with paragraph (3) shall be certified by the authorized person to the
satisfaction of the Building Authority.

178. (1) Every excavated well except in solid rock shall be
properly lined for its entire depth with brickwork. or other suitable
material and such lining shall be provided with suitably fixed iron
rungs foot rests not more than 600 mm apart for the entire depth.

(2) The lining of every well shall be rendered impervious for a
depth of not less than 1 800 mm from the level of the adjoining
ground.

(3) A suitable filter of clean broken stone, gravel or sand shall
be provided at the bottom of every excavated well.

179. (1) Access for cleaning purposes must be provided for
every excavated well.

(2) An efficient close-fitting cover shall be fitted over every
well.





180. (1) The top of every well shall be suitably protected to
prevent the direct entry of any surface water or sullage water.

(2) The ground surface adjoining the top of every well shall be
paved with suitable impervious material for a distance of not less
than 1 m in every direction from the side of such well and so
constructed as to slope away from the well to a suitable channel.

181. A suitable parapet wall, not less than 750 mm in height,
shall be constructed around the top of every well from which water
is to be drawn by means of a bucket.

PART XVI

FIRE RESISTING CONSTRUCTION

182. In this Part--

'basement- means any storey of a building or any compartment
which is wholly below the level of the street or streets on which
such building abuts, or being partially below such level has no
access to such streets in the event of fire;

'compartment of a building' means any volume, or floor area in any
1 storey, in any building assessed as a unit for the purposes of
Table XLIII;

'elements of construction' means-

(a) any floor, beam, column or hanger.

(b) any load bearing wall or load bearing member; and

(c) any staircase and the landings and supports thereto;


---F.R.P.' means the period for which the element of construction is
capable of resisting the action of fire when tested in accordance
with BS 476:Part 8 or as specified in the Third Schedule;

'staircase' includes landings and lobbies attached thereto without
any intervening enclosure.

183. Every building shall be separated from any adjoining
building by a wall having an F.R.P. of not less than 4 hours.

184. (1) Each element of construction in a building or com-
partment of a building shall have an F.R.P. not less than that
specified in Table XLIII appropriate to the use and the volume, or
floor area in any one storey, as the case may be:

Provided that each element of construction in any building
which exceeds 3 storeys shall in no case have an F. R.P. of less than 1
hour.





TABLE XLITI






1 2 3

Volume, or floor area in any 1 storey Fire
Use (as the case may be) resistance
period

6 transformer In all cases. 2 hours.
chamber or
purpose
involving a
similar fire risk.
7 Garage (a) Not more than 45 m2 in floor area. 1/2 hour.
purposes. (b) More than 45 m2 but not more than 90 m2 1 hour.
in floor area.
(c) More than 90 m2 in floor area. 2 hours.

(2) Save with the consent of the Building Authority the floor
area of any 1 compartment used for btustorage or warehouse
purposes shall not exceed 700 m2.

(3 ) Where a single storey building does not exceed 7 000 m3 in
volume or 7.5 m in height, steel work therein other than columns
and beams in external or party walls may, subject to the provisions
of PART XI (Structural Use of Steel) be unprotected.

(4) The joints of and any elements of construction shall be
tight and proof against the passage of smoke or flame.

185. Every compartment of a building shall be separated from
any adjoining compartment by a wall or floor having an F.R.P. of
not less than 2 hours, and if 1 or both compartments demand a
longer period of fire resistance, the separating wall or floor between
the compartments shall have an F.R.P. of 4 hours:

Provided that where adjoining compartments are used solely
for domestic purposes the separating wall or floor between the
compartments shall have an F.R.P. of 1 hour.

186. (1) Each element of construction of a staircase shall have
an F.R.P. not less than the period required for each element of
construction of the building or compartment in which the staircase is
situated:

Provided that this paragraph shall not apply to staircases
enclosed in accordance with paragraph (2).

(2) Where a staircase serves more than 1 compartment of a
building-

(a) such staircase shall be enclosed by walls, and

(b)such walls shall have an F.R.P. not less than the longer
period required for the elements of construction in any
compartment so served:

Provided that this paragraph shall not apply to any external
staircases open to the weather on at least 2 sides.





187. Where compartments of a building to which the provisions
of regulation 185 apply are situated in the topmost storey of a
building, the walls required by that regulation shall be carried up to
the underside of the roof of the storey:
Provided that where the ceiling is formed beneath a pitched
roof, the walls need only be carried up to the underside of the roof so
as to form in the roof space vertical firechecks at a distance apart not
exceeding 35 m.

188. Walls separating compartments of a building or enclosing
staircases, in accordance with regulation 185 or 186 may have
openings where-
(a) the door and frame of such opening has an F. R.R-
(i) in the case of walls separating compartments, 1 hour,
or.
(ii) in the case of walls enclosing staircases, 1 the period
requried for such walls:
Provided that in no case shall the door have an F.R.P.
less that 1/2 hour; and
(b) such door is self-closing, except in the case of such a door
in a domestic building which does not lead from a staircase
to a corridor used in common.

189 (1) Borrowed lights may not be provided in walls separat-
ing compartments of buildings in accordance with regulation 185.
(2) Where borrowed lights are provided in any wall enclosing,
in accordance with regulation 186, a staircase-
(a) the area of such lights shall be not more than -g' of the total
area of the wall; and
(b) the lights shall be glazed with a 6 mm wired glass or
covered with glass bricks or blocks.

190. Each element of construction in a basement shall have an
F.R.P. of 4 hours.

PART XVII
MISCELLANEOUS

191. Where any doors for disabled persons are provided in
accordlince with regulation 72* of the Building (Planning) Regula-
tion
(a)double-action self-closing doors shall have a check mech-
anism to prevent the doors swinging beyond the closed
position and a transparent panel with a bottom edge not
more than one metre and the top edge not less than 1.5 m
above floor level;
(b)door handles shall be not less than 900 mm and not more
than 1.05 m above floor level, measured from the top sur-
face of the grip; and
(c) door thresholds shall not exceed 25 mm in height.





FIRST SCHEDULE

METHODS FOR DETERMINING THE RESISTANCE TO
CRUSHING OF CONCRETE

PART 1

GENERAL

1. (1) In this Schedule unless the contrary appears-

'average resistance to crushing' means the arithmetical mean of the resistances to
crushing of a stated number of cubes;

.,consecutive cubes- means cubes made from consecutive samples orconcrete as taken
during the work, and tested at the same age;

'designed mean resistance to crushing- means the mean resistance to crushing to be
aimed for in designing a mix to comply with a specified resistance to crushing:

-designed standard deviation- is the standard deviation adopted in designing a mix.,

.,mean resistance to crushing' means the arithmetical mean resistance to crushing of
all the concrete of a particular grade produced in a given period of time;

'preliminary test' means a test made in accordance with BS 188 1: Parts 3 and 4: 1970
both prior to the commencement of the work and subsequently whenever any
important change is to be made in the materials or in the proportions of the
materials to he used, to ascertain the suitability of the available materials or to
determine suitable mix proportions.

..range' means the difference between the highest and lowest value in a set.

'seC means a stated number of consecutive individual results;

'specified resistance to crushing' means for ordinary concretes and Quality A
concretes, the resistance to crushing specified in Tables IV and V for the
appropriate grade, for special mixes and designed mixes. the particular resistance
to crushing within the limits of Table VI appropriate to the permissible stresses
adopted for the structural design;

-standard deviation- means a measure of variability calculated from the resistances
to crushing of the individual cubes tested at a given age each representing a
different batch of concrete having the same specified resistance to crushing;

'works resistance to crushing' means the resistance to crushing obtained from works
tests,

'works test' means a test made in accordance with BS 1881: Parts 3 and 4: 1970
during the course of the work to assess or prove the quality of the concrete used
in the work.

(2) The mean resistance to crushing may be estimated from tests on such a
number of cubes of concrete as may be approved by the Building Authority generally
or for a particular grade of concrete or in a particular case.

(3) The standard deviation, may be calculated from either of the following
equations:







where- Ex is the sum of all the individual results;
E(x)2 is the sum of the,.squares of all the individual results;
E(x-x)2 - is the sum of tyel,,quares of the differences between the
average, x, of all the individual results and each in-
dividilal result, x, in turn; and
n is the number results. which should be not less than
40 for a reasonably accurate estimate of the standard
deviation.

2. The resistance to crushing of concrete shall be determined by testing
standard 150 mm cu of the appropriate age made. cured and tested in accordance
with the approprite provisions of BS 1881: Parts 3 and 4: 1970 and in accordance
with this Schedule.

3. (1) Samples of oncrete for making test cubes shall be taken in accordance
with BS 1881: Part 1: 19 .
(2) For the purpose of determining the resistance to crushing at a particular age
after mixing, each works cube shall be made from a difrerent batch of concrete.
(3) For the purpose of checking the ratio of resistances to crushing at different
ages 3 cubes shall be made from the same batch of concrete for each age for which the
ratio is required.

4. (1) The following information shall be recorded-
(a) identification mark of each cube..
(b) designation of concrete:
(c) brand and type of cement
(d ) types of aggregates:
(e) mix proportions;
(f) water/cement ratio;
(g) dates of moulding and testing;
(h) location after placing in the work of the concrete from which the sample was
taken;
(i) number of cubes and their marks:
(j) mixer from which sample was taken (if more than 1 mixer is used).
(k) weather conditions; and
(l) curing conditions.
(2) Copies of test reports for concretes of Quality A. special mixes and designed
mixes hall be submitted to the Building Authority within 21 days after testing.
(3) Test reports for concretes of ordinary quality shall be kept and made
avail e for inspection if necessary. until at least 6 months after the completion of the
building works.

PART II

CONCRETE OF ORDINARY QUALITY

5. (1) Preliminary tests are not required for concrete of ordinary quality.
(2) (a) The works resistance to crushing of concrete of ordinary quality shall
be determined from sets of 3 consecutive cubes from the same grade of
concrete tested at the same age.

(b)At least 1 cube should be made for each grade of concrete on each day that it
is used.

6. The specified resistance to crushing for the appropriate grade shall be
deemed to have been attained if the average resistance to crushing of each set of 3
consecutive cubes is not less than the specified resistance and no individual result is
less than 85 per cent of the specified resistance.





PART Ill

CONCRETES OF QUALITY A

7. (1) (a) Preliminary tests should be made for concrete of Quality A.

(b)6 cubes shall be made for each test and 3 of these cubes shall be tested at the
age of 7 days and the remaining 3 at 28 days.

(2)(a) The works resistance to crushing of Quality A concrete shall be
determined from sets of 3 consecutive cubes from the same grade ofconerete
tested at the same age.

(b)For each age at which the resistance to crushing is to be determined at least 3
cubes shall be made for each grade of concrete on each day it is used.

8. The specified resistance to crushing for the appropriate grade shall be
deemed to have been obtained if-

(a)none of the individual crushing resistances is less than the specified
resistance to crushing; or

(b) if the average resistance to crushing of eMh set of 3 consecutive cubes is not
less than the specified resistance and the difference between the greatest and
least result of the set is not more than 20 per cent of that average.

PART IV

CONCRETES OF SPECIAL MIXES

9. (1) (a) Preliminary tests shall be made for special mixes.

(b)For each preliminary test 6 cubes shall be made from each of 2 batches of
the same mix proportions.

(c) 3 cubes ofeach set of 6 cubes shall be tested at 7 days and the remaining 3 at
28 days.

(2)(a) The works resistance to crushing of concrete of special mixes shall be
determined from a set of 3 cubes tested at the same age.

(b)For each age at which the resistance to crushing is to be determined. at least
1 set of 3 cubes shall be made for each grade of concrete on each day it is
used and if more than 75 m3 of any grade is used in a day 1 set shall be
made for each 75 m3 or part thereof.

10. The specified resistance to crushing in accordance with Table VI shall be
deemed to have been attained if-
(a)none of the individual resistances to crushing is less than the specified
resistance to crushing, or

(b)the average resistance to crushing of each set of 3 consecutive cubes is not
less than the specified resistance to crushing and the difrerence between the
greatest and least result of the set is not more than 20 per cent of that
average, provided that ifindividual cubes from 2 consecutive sets fall below
the required resistance to crushing the mix shall be adjusted to give a higher
strength so that not more than 1 set in 3 consecutive sets shall contain
individual results lower than the specified resistance to crushing.

PART V

CONCRETES OF DESIGNED MIXES

11. (1) (a) Preliminary tests shall be made for designed mixes.



(b)For each test 6 cubes shall be made from each of 3 batches ofthe same mix
proportions.





(e)3 cubes of each set of 6 cubes shall be tested at 7 days and the remaining 3 at
28 days.
(2)(a) The works resistance to crushing of designed mixes shall he determined
from a statistical analysis of not less than 40 cube tests at the same age.
(b) A sample of concrete shall be taken on 8 separate occasions during each of
the first 5 days of usinreafter at least 3 samples shall be
taken on each day thatd if more than 120 m3 is used in a
day a sample shall be taken from each 40 m3 or part thereof.
(c) 1 cube from each sample taken under sub-paragraph (b) shall be tested at 7
days and 1 additional cube from at least every fourth sample taken under
sub-paragraph (b) shall be tested at 28 days.
12. The preliminary test under sub-paragraph 11 (1) shall be deemed to be
acceptable if the average of the resistances to crushing of the 3 sets of 3 cubes tested at
the specified age exceeds the specified resistance to crushing by not less than 2 times
the designed standard deviation. If the difference between the greatest and least
individual results for any set of 3 cubes is more than 20 per cent of the mean resistance
to crushing for which the mix has been designed an additional set of 3 cubes shall be
made and tested.

13. (1) The specified resistance to crushing of designed mixes shall be deemed
to have been attain if the works test results. when examined individually and in
consecutive (but not overlapping) sets of 4 cubes, satisfy each of the following
conditions-
(a)no individual result is less than 80 per cent of the specified resistance to
crushing;
(b)not more than 2 individual results of any 40 consecutive results fall below
the specified resistance to crushing
(c)the range of any set is not more than 4 times the designed standard
deviation;
(d) the average of any set is not less than the specified resistance to crushing plus
the designed standard deviation;

(e) the average of not more than 1 set in any 10 consecutive sets is less than the
specified resistance to crushing plus 1 1/3 times the designed standard devia-
tion; and

f) the overall average of not less than 40 consecutive individual resistances is
not less than the specified resistance to crushing plus 2 times the standard
deviation of those resistances.
(2) If sub-paragraph (1) (a) is not satisfied the parts of the structure made from
the batch of concrete from which the low test result was obtained shall be subjected to
individual inspection and testing.

(3) (i) If sub-paragraph (1)(b), (c). (d) or (e) is not satisfied in the first 10 sets
the mix shall be modified to increase the resistance to crushing.
(ii) If sub-paragraph (1) (b). (c). (d) or (e) is not satisfied in subsequent
sets, the overall average of the previous 40 consecutive results including the
non-complying set. shall be calculated and examined for compliance with
sub-paragraph (1) (f).

(iii) If sub-paragraph (1)(f)is not satisfied the mix shall be modified to
increase the resistance to crushing until it complies therewith.

SECOND SCHEDULE [reg. 19(7).]
DESIGN OF CONCRETE MIXES

1. (1) The proportions of concretes of special mixes and of design mixes shall
be selected within the limits of Table VI so that the designed mean resistance to
crushing of the concrete exceeds the specified resistance to crushing (as defined in the
First Schedule) by a suitable margin and so that the workability is adequate for the
means of compaction available on the site.
(2) In designing a mix to satisfy these requirements attention should be given to
the following factors-





(a) specified strength,
(b) durability;
(c) degree of control;
(d) age at which a particular resistance to crushing is required:
(e) size of members,
(1) type of cement:
(g) spacing of reinforcement;
(h) maximum size of aggregate;
(i) shape and grading of aggregates available.
(j) available means of compaction:
(k) ratio of water to cement ratio, and
(1) ratio of aggregate to cement ratio.
2. (1) The designed mean resistance to crushing of special mixes shall initially
exceed the specified resistance to crushing by a margin of not less than 14 MPa.
(2) Where the works tests show to the satisfaction of the Building Authority
that the standard of acceptance can be maintained with a smaller margin, the mix
may be redesigned with a margin of not less than 10 MPa.

3. (1) The designed mean resistance to crushing of designed mixes shall
exceed the specified resistance to crushing by a margin of not less than 2 times the
designed standard deviation.

(2) Where there is no previous information on the standard deviation which
may be expected under similar conditions, the designed standard deviation used
initially shall be not less than 7 MPa for the purpose of ensuring that the margin
initially taken shall be not less than 14 MPa.

(3) Where there is previous information on the standard deviation which can he
expected under similar conditions or where the standard deviation can be calculated
from the results of at least 40 works cube tests. such standard deviation ma% be used
as a basis for designing or redesigning the mix:
Provided that the standard deviation used in designing or redesigning a mix shall
be not less than 3.5 MPa.

4. (1) For concrete which is protected from the weather or from corrosive
conditions, the cement content and the ratio of water to cement will generally be
selected on the basis of the required resistance to crushing and workability.
(2) For exposed concrete the maximum ratio of water to cement maybe limited
by the requirements of durability rather than strength. The Table hereto 'sets out the
maximum ratio of water to cement for various types of exposure. The cement content
should be selected so that the required workability can be obtained without exceeding
the maximum ratios of water to cement.

TABLE

MAXIMUM RATIOS OF WATER TO CEMENT (BY MASS) FOR
DURABILITY OF DIFFERENT TYPES OF STRUCTURE UNDER VARIOUS
DEGREES OF EXPOSURE






THIRD SCHEDULE [reg. 182.]
MINIMUM REQUIREMENTS FOR CONSTRUCTION AND
MATERIALS TO BE CAPABLE OF RESISTING THE ACTION
OF FIRE FOR SPECIFIED PERIODS
TABLE A
WALLS AND PARTITION'S

Construction and Materials Minimum thickness in mm
(excluding plaster)
for period of




In this Table:-
Class 1 Aggregate means foamed slag, pumice, blast furnace slag. crushed brick
and burnt clay products, well burned clinker. crushed limestone.
Class 2 Aggregate means flint, gravel. granite and all crushed natural stones
other than limestone.





TABLE B

FLOORS AND LANDINGS






TABLE C

STEEL COLUMNS AND BEAMS







In this Table:-
'Solid Protection' --- means casing which is bedded close up to the steel without
any intervening cavities and with all joints in that easing made full and solid.
'Hollow Protection' - means that there is a void between the protective material
and the steel. All hollow protection to columns shall be effectively scaled at
each floor level.

Reinforcement-where reinforcement is required in this Table. that reinforce-
ment shall consist of steel binding wire not less than 2.5 mm diameter. or a
steel mesh weighing not less than 0.5 kg M2. In the case of concrete
protection. the spacing of that reinforcement shall not exceed 300 mm in any
direction.





TABLE D

REINFORCED CONCRETE COLUMNS AND REAMS
















TABLE E

STAIRS






TABLE F

GLAZING



TABLE G

DOORS L.N. 9/75. L.N. 42/75. L.N. 294/76. L.N. 95/78. L.N. 76/81. L.N. 234/82. L.N. 268/83. 73 of 1983. L.N. 363/84. Citation. Interpretation. 73 of 1983, s. 3. L.N. 234/82. L.N. 294/76. Materials. British Standard Specification or British Standard Code of Practice. Permissible stresses not to be exceeded. Dispersion of load. Overloading. Support for adjoining and other buildings. Bricks and building blocks. L.N. 294/76. L.N. 294/76. Cement. L.N. 294/76. Lime. Sand. L.N. 294/76. Red earth. Water. Cement mortar. Cement-lime mortar. Lime mortar. Aggregate. L.N. 294/76. L.N. 294/76. L.N. 95/78. Concrete. First Schedule and Second Schedule. L.N. 294/76. L.N. 294/76. L.N. 294/76. L.N. 95/78. L.N. 294/76. Reinforcement for concrete. L.N. 294/76. Structural and rivet steel. L.N. 294/76. L.N. 42/75. Timber. L.N. 294/76. L.N. 294/76. Materials for damp-proofing. Buildings to be designed for wind effects. L.N. 268/83. Design loads. L.N. 294/76. L.N. 294/76. L.N. 95/78. L.N. 294/76. L.N. 294/76. L.N. 294/76. L.N. 294/76. Test load. Notice as to load. L.N. 294/76. L.N. 76/81. Site formation works. L.N. 234/82. Bulk excavation in scheduled area. L.N. 234/82. Ground investigation in scheduled area. Foundations. Construction of foundations. L.N. 294/76. Site investigation. Settlement. Safe bearing capacity. Allowable bearing pressure. L.N. 294/76. L.N. 294/76. L.N. 294/76. L.N. 95/78. Permissible pressure on concrete. L.N. 294/76. Piling. L.N. 294/76. L.N. 294/76. Pressure from adjacent ground. Footings. Caissons. L.N. 42/75. L.N. 42/75. L.N. 294/76. Grouting. Covering of sites. L.N. 294/76. L.N. 294/76. L.N. 294/76. Areas, etc. to be paved. L.N. 294/76. Certain floors to be impermeable. Lowest floor to be above ground level. L.N. 294/76. Ventilation below wood floors. L.N. 294/76. Construction of wood floors. Skirting. Construction and bonding of walls. Buildings over 4 storeys or 15 m in height. L.N. 294/76. Application of regulations. L.N. 294/76. Rules for measuring height of storeys and height of walls. L.N. 294/76. Rules for measuring length of walls. Thickness of external walls and party walls of buildings other than public buildings or buildings of the warehouse class. L.N. 294/76. Thickness of external and party walls of public buildings and buildings of the warehouse class. L.N. 294/76. L.N. 294/76. L.N. 294/76. Thickness of internal load bearing walls. L.N. 294/76. Recesses and openings. L.N. 294/76. L.N. 294/76. Loads on walls. L.N. 294/76. Corbelling and overhanging work. Thickness of walls where difference in ground levels. L.N. 294/76. (Cap. 123, sub. leg.) Thickness of external walls of certain small buildings. L.N. 294/76. Cavity walls. L.N. 294/76. Glass block walls. L.N. 294/76. Parapet walls. L.N. 294/76. Boundary walls and fences. L.N. 294/76. Definition of slenderness ratio. Maximum compressive stresses in walls or piers of bricks or building blocks. L.N. 294/76. Maximum compressive stresses in walls and piers of concrete. L.N. 294/76. L.N. 294/76. L.N. 95/78. Eccentric loads and lateral forces on slender walls. Panel walls. L.N. 294/76. L.N. 42/75. Cladding. L.N. 294/76. Party walls to be carried up to roof. Timber not to be built into walls. Damp-proof courses. L.N. 294/76. Fireplaces and stoves to have hearths. L.N. 294/76. Fireplace openings. L.N. 294/76. Fireplaces to have chimneys and flues. L.N. 294/76. Chimney stacks to be carried above roof. L.N. 294/76. Combustible materials in proximity to chimneys. L.N. 294/76. Chimney shafts. L.N. 294/76. Open cooking slabs to have hoods. L.N. 294/76. Ceilings over fireplaces to be protected. L.N. 294/76. Roofs to be covered. L.N. 294/76. Roofs to be weatherproof. Accessible roofs to have parapet or railings. L.N. 294/76. Hollow ceilings. Steel framed and reinforced concrete structures. (Cap. 123, sub. leg.) (Cap. 123, sub. leg.) (Cap. 123, sub. leg.) Finished sizes of structural timber. L.N. 294/76. Minimum load on ceiling joists and floor boards. L.N. 294/76. Maximum permissible stresses in structural timber. L.N. 294/76.* Maximum permissible stresses for posts and struts. L.N. 294/76. Effective length of posts and struts. Maximum deflexion. Stresses due to imposed load on pitched roof. Combined bending and axial stresses. Joints and connexions. Cleaning and protection against corrosion. Protection. L.N. 294/76. Stresses (steel other than columns and struts). L.N. 294/76. L.N. 294/76. L.N. 294/76. L.N. 294/76. Stresses in columns and struts. L.N. 294/76. L.N. 294/76. Stress due to wind. Combined stresses. Grillage beams. L.N. 294/76. Effective length of columns and struts. Ends of columns. Bases for columns. L.N. 294/76. L.N. 294/76. Joints in columns. L.N. 294/76. Filler floor beams. L.N. 294/76. L.N. 294/76. Deflexion and span of beams. L.N. 294/76. Thickness of steel. L.N. 294/76. Bolts. Rivets and riveting. L.N. 294/76. Welding. L.N. 294/76. Fabrication and erection. L.N. 294/76. Saving. L.N. 294/76. (Cap. 123, sub. leg.) Reinforcement. Minimum cover of reinforcement. L.N. 294/76. L.N. 95/78. Stresses in reinforced concrete. L.N. 294/76. Stresses in reinforcement. L.N. 294/76. Stresses in reinforced concrete columns. Effective length of columns. Stresses due to wind. L.N. 294/76. Longitudinal reinforcement for columns. L.N. 294/76. Transverse or helical reinforcement for columns. L.N. 294/76. Diameter of reinforcements. L.N. 294/76. Spacing of reinforcements. L.N. 294/76. Shear reinforcement. Stirrups. L.N. 294/76. Reinforcement in solid slabs. Compression reinforcement. L.N. 294/76. Reinforced concrete walls. L.N. 294/76. Welding of reinforcement. L.N. 294/76. Basis of design. Stiffness of members. L.N. 294/76. Effective span. T-beams and L-beams. Bending moments. Beams and slabs spanning in 1 direction. Slabs spanning in 2 directions at right angles with uniformly distributed loads. Distribution of concentrated load on solid slabs. Trimming for openings. Resistance to shear. L.N. 294/76. Bond and anchorage. Floors and roofs of ribbed and hollow block construction. L.N. 294/76. Permissible loads on columns. L.N. 294/76. Footings. Method of design for flat slab construction. Definitions and notation for flab slab construction. Division of panels in flat slab construction. Minimum thickness of flat slabs. L.N. 294/76. Shearing stresses in flat slabs. Columns and column heads in flat slab construction. L.N. 294/76. L.N. 294/76. Openings in panels in flab slab construction. Drops in flat slab construction. Reinforcement of flat slabs generally. L.N. 294/76. Panel with marginal beams or walls in flat slab construction. Design of flat slabs as continuous frames. Empirical design of flat slabs. Maximum permissible stresses in special and designed mixes. First Schedule. L.N. 294/76. Increase in maximum permissible steel stresses. L.N. 294/76. L.N. 294/76. Stresses in columns of special and designed mixes. Stiffness of members with higher steel and concrete stresses. L.N. 294/76. Load factor method of design. Slender beams and long columns designed by the load factor method. Simplified formulae for rectangular beam and solid slab sections in load factor method. L.N. 294/76. Simplified formulae for T-beams or L-beams in load factor method. Formulae for short columns subject to both direct load and bending in load factor method. L.N. 294/76. L.N. 95/78. L.N. 95/78. Wharves, piers and sea-walls. Materials and design. L.N. 76/81. Foundations. Brickwork. Masonry. Bond courses required. L.N. 294/76. Weep holes. L.N. 294/76. L.N. 76/81. [*10.4.81.] (L.N. 76/81.) Copings and parapets. L.N. 294/76. Surface channels. Permission from Building Authority to sink or reopen wells. Wells prohibited in certain places. Wells to be of sufficient depth and diameter. Wells to be lined and filter required. L.N. 294/76. Access for cleaning and close-fitting cover required. Channels and paving to ground surface adjoining top of wells required. L.N. 294/76. Parapet wall required where water is drawn by a bucket. L.N. 294/76. Interpretation. L.N. 294/76. Third Schedule. Adjacent buildings. Elements of construction within buildings. L.N. 294/76. L.N. 294/76. Adjoining compartments to be separated. Staircases. Topmost storeys. L.N. 294/76. Openings in walls separating compartments or enclosing staircases. Borrowed lights. L.N. 294/76. Basements. L.N. 363/84. Doors for the disabled. (Cap. 123, sub. leg.) [*In operation on 1.8.85] [reg. 19(7).] Interpretation. L.N. 294/76. L.N. 294/76. Standard 150mm cubes. L.N. 294/76. Samples of concrete for making cubes. L.N. 294/76. Records. Number of cubes for ordinary quality concrete. Standard of acceptance for ordinary quality concrete. Number of cubes for Quality A concrete. Standard of acceptance for Quality A concrete. Number of cubes for concrete of special mixes. L.N. 294/76. Standard of acceptance for preliminary and works tests of concrete of special mixes. Number of cubes for concrete of designed mixes. L.N. 294/76. Standard of acceptance for preliminary tests of concrete of designed mixes. Standard of acceptance for works tests of concrete of designed mixes. General considerations. Criteria for special mixes. L.N. 294/76. Criteria for designed mixes. L.N. 294/76. Durability. L.N. 294/76. L.N. 294/76.

L.N. 9/75. L.N. 42/75. L.N. 294/76. L.N. 95/78. L.N. 76/81. L.N. 234/82. L.N. 268/83. 73 of 1983. L.N. 363/84. Citation. Interpretation. 73 of 1983, s. 3. L.N. 234/82. L.N. 294/76. Materials. British Standard Specification or British Standard Code of Practice. Permissible stresses not to be exceeded. Dispersion of load. Overloading. Support for adjoining and other buildings. Bricks and building blocks. L.N. 294/76. L.N. 294/76. Cement. L.N. 294/76. Lime. Sand. L.N. 294/76. Red earth. Water. Cement mortar. Cement-lime mortar. Lime mortar. Aggregate. L.N. 294/76. L.N. 294/76. L.N. 95/78. Concrete. First Schedule and Second Schedule. L.N. 294/76. L.N. 294/76. L.N. 294/76. L.N. 95/78. L.N. 294/76. Reinforcement for concrete. L.N. 294/76. Structural and rivet steel. L.N. 294/76. L.N. 42/75. Timber. L.N. 294/76. L.N. 294/76. Materials for damp-proofing. Buildings to be designed for wind effects. L.N. 268/83. Design loads. L.N. 294/76. L.N. 294/76. L.N. 95/78. L.N. 294/76. L.N. 294/76. L.N. 294/76. L.N. 294/76. Test load. Notice as to load. L.N. 294/76. L.N. 76/81. Site formation works. L.N. 234/82. Bulk excavation in scheduled area. L.N. 234/82. Ground investigation in scheduled area. Foundations. Construction of foundations. L.N. 294/76. Site investigation. Settlement. Safe bearing capacity. Allowable bearing pressure. L.N. 294/76. L.N. 294/76. L.N. 294/76. L.N. 95/78. Permissible pressure on concrete. L.N. 294/76. Piling. L.N. 294/76. L.N. 294/76. Pressure from adjacent ground. Footings. Caissons. L.N. 42/75. L.N. 42/75. L.N. 294/76. Grouting. Covering of sites. L.N. 294/76. L.N. 294/76. L.N. 294/76. Areas, etc. to be paved. L.N. 294/76. Certain floors to be impermeable. Lowest floor to be above ground level. L.N. 294/76. Ventilation below wood floors. L.N. 294/76. Construction of wood floors. Skirting. Construction and bonding of walls. Buildings over 4 storeys or 15 m in height. L.N. 294/76. Application of regulations. L.N. 294/76. Rules for measuring height of storeys and height of walls. L.N. 294/76. Rules for measuring length of walls. Thickness of external walls and party walls of buildings other than public buildings or buildings of the warehouse class. L.N. 294/76. Thickness of external and party walls of public buildings and buildings of the warehouse class. L.N. 294/76. L.N. 294/76. L.N. 294/76. Thickness of internal load bearing walls. L.N. 294/76. Recesses and openings. L.N. 294/76. L.N. 294/76. Loads on walls. L.N. 294/76. Corbelling and overhanging work. Thickness of walls where difference in ground levels. L.N. 294/76. (Cap. 123, sub. leg.) Thickness of external walls of certain small buildings. L.N. 294/76. Cavity walls. L.N. 294/76. Glass block walls. L.N. 294/76. Parapet walls. L.N. 294/76. Boundary walls and fences. L.N. 294/76. Definition of slenderness ratio. Maximum compressive stresses in walls or piers of bricks or building blocks. L.N. 294/76. Maximum compressive stresses in walls and piers of concrete. L.N. 294/76. L.N. 294/76. L.N. 95/78. Eccentric loads and lateral forces on slender walls. Panel walls. L.N. 294/76. L.N. 42/75. Cladding. L.N. 294/76. Party walls to be carried up to roof. Timber not to be built into walls. Damp-proof courses. L.N. 294/76. Fireplaces and stoves to have hearths. L.N. 294/76. Fireplace openings. L.N. 294/76. Fireplaces to have chimneys and flues. L.N. 294/76. Chimney stacks to be carried above roof. L.N. 294/76. Combustible materials in proximity to chimneys. L.N. 294/76. Chimney shafts. L.N. 294/76. Open cooking slabs to have hoods. L.N. 294/76. Ceilings over fireplaces to be protected. L.N. 294/76. Roofs to be covered. L.N. 294/76. Roofs to be weatherproof. Accessible roofs to have parapet or railings. L.N. 294/76. Hollow ceilings. Steel framed and reinforced concrete structures. (Cap. 123, sub. leg.) (Cap. 123, sub. leg.) (Cap. 123, sub. leg.) Finished sizes of structural timber. L.N. 294/76. Minimum load on ceiling joists and floor boards. L.N. 294/76. Maximum permissible stresses in structural timber. L.N. 294/76.* Maximum permissible stresses for posts and struts. L.N. 294/76. Effective length of posts and struts. Maximum deflexion. Stresses due to imposed load on pitched roof. Combined bending and axial stresses. Joints and connexions. Cleaning and protection against corrosion. Protection. L.N. 294/76. Stresses (steel other than columns and struts). L.N. 294/76. L.N. 294/76. L.N. 294/76. L.N. 294/76. Stresses in columns and struts. L.N. 294/76. L.N. 294/76. Stress due to wind. Combined stresses. Grillage beams. L.N. 294/76. Effective length of columns and struts. Ends of columns. Bases for columns. L.N. 294/76. L.N. 294/76. Joints in columns. L.N. 294/76. Filler floor beams. L.N. 294/76. L.N. 294/76. Deflexion and span of beams. L.N. 294/76. Thickness of steel. L.N. 294/76. Bolts. Rivets and riveting. L.N. 294/76. Welding. L.N. 294/76. Fabrication and erection. L.N. 294/76. Saving. L.N. 294/76. (Cap. 123, sub. leg.) Reinforcement. Minimum cover of reinforcement. L.N. 294/76. L.N. 95/78. Stresses in reinforced concrete. L.N. 294/76. Stresses in reinforcement. L.N. 294/76. Stresses in reinforced concrete columns. Effective length of columns. Stresses due to wind. L.N. 294/76. Longitudinal reinforcement for columns. L.N. 294/76. Transverse or helical reinforcement for columns. L.N. 294/76. Diameter of reinforcements. L.N. 294/76. Spacing of reinforcements. L.N. 294/76. Shear reinforcement. Stirrups. L.N. 294/76. Reinforcement in solid slabs. Compression reinforcement. L.N. 294/76. Reinforced concrete walls. L.N. 294/76. Welding of reinforcement. L.N. 294/76. Basis of design. Stiffness of members. L.N. 294/76. Effective span. T-beams and L-beams. Bending moments. Beams and slabs spanning in 1 direction. Slabs spanning in 2 directions at right angles with uniformly distributed loads. Distribution of concentrated load on solid slabs. Trimming for openings. Resistance to shear. L.N. 294/76. Bond and anchorage. Floors and roofs of ribbed and hollow block construction. L.N. 294/76. Permissible loads on columns. L.N. 294/76. Footings. Method of design for flat slab construction. Definitions and notation for flab slab construction. Division of panels in flat slab construction. Minimum thickness of flat slabs. L.N. 294/76. Shearing stresses in flat slabs. Columns and column heads in flat slab construction. L.N. 294/76. L.N. 294/76. Openings in panels in flab slab construction. Drops in flat slab construction. Reinforcement of flat slabs generally. L.N. 294/76. Panel with marginal beams or walls in flat slab construction. Design of flat slabs as continuous frames. Empirical design of flat slabs. Maximum permissible stresses in special and designed mixes. First Schedule. L.N. 294/76. Increase in maximum permissible steel stresses. L.N. 294/76. L.N. 294/76. Stresses in columns of special and designed mixes. Stiffness of members with higher steel and concrete stresses. L.N. 294/76. Load factor method of design. Slender beams and long columns designed by the load factor method. Simplified formulae for rectangular beam and solid slab sections in load factor method. L.N. 294/76. Simplified formulae for T-beams or L-beams in load factor method. Formulae for short columns subject to both direct load and bending in load factor method. L.N. 294/76. L.N. 95/78. L.N. 95/78. Wharves, piers and sea-walls. Materials and design. L.N. 76/81. Foundations. Brickwork. Masonry. Bond courses required. L.N. 294/76. Weep holes. L.N. 294/76. L.N. 76/81. [*10.4.81.] (L.N. 76/81.) Copings and parapets. L.N. 294/76. Surface channels. Permission from Building Authority to sink or reopen wells. Wells prohibited in certain places. Wells to be of sufficient depth and diameter. Wells to be lined and filter required. L.N. 294/76. Access for cleaning and close-fitting cover required. Channels and paving to ground surface adjoining top of wells required. L.N. 294/76. Parapet wall required where water is drawn by a bucket. L.N. 294/76. Interpretation. L.N. 294/76. Third Schedule. Adjacent buildings. Elements of construction within buildings. L.N. 294/76. L.N. 294/76. Adjoining compartments to be separated. Staircases. Topmost storeys. L.N. 294/76. Openings in walls separating compartments or enclosing staircases. Borrowed lights. L.N. 294/76. Basements. L.N. 363/84. Doors for the disabled. (Cap. 123, sub. leg.) [*In operation on 1.8.85] [reg. 19(7).] Interpretation. L.N. 294/76. L.N. 294/76. Standard 150mm cubes. L.N. 294/76. Samples of concrete for making cubes. L.N. 294/76. Records. Number of cubes for ordinary quality concrete. Standard of acceptance for ordinary quality concrete. Number of cubes for Quality A concrete. Standard of acceptance for Quality A concrete. Number of cubes for concrete of special mixes. L.N. 294/76. Standard of acceptance for preliminary and works tests of concrete of special mixes. Number of cubes for concrete of designed mixes. L.N. 294/76. Standard of acceptance for preliminary tests of concrete of designed mixes. Standard of acceptance for works tests of concrete of designed mixes. General considerations. Criteria for special mixes. L.N. 294/76. Criteria for designed mixes. L.N. 294/76. Durability. L.N. 294/76. L.N. 294/76.

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