Section		Section
Aggregate Coarse ……………..	5(8)	Empirically constructed Brick	52(1)
Fine ……………..	5(5) & 6	Masonry	30
Anchorage to joisted timber and precast concrete floors	. . 25	Design Constructed of masonry construction	63 &82
Arches over openings	17	Design general requirements for	64
Balustrade -walls empirically constructed Brick	53(3)	Dimensions subject to tolerances	3
general	27(7)	Dispersion forces	65
Basement -walls, empirically constructed brick	46	eccentric or lateral forces stresses due to	72
Beams & rafters ends of	24	empirical construction bearings for beams other than timber in	41
Beams, other than timber in empirical construction bearings for	41	minimum requirements for materials for	42
Block masonry axial stresses in	69	Existing masonry, use of	16
Blocks cay, concrete, glass and sand -cement.	5(9) & (10)	External walls to be weatherproof,	6
gypsum general requirements for	36	Faced walls	29
hollow glass, general requirements for	37	Facings, veneer (see under Veneered Walls)
soil cement	5(12)	Floors joisted timber and precast concrete, anchorage to.	25
Bond	11	loadings and spans in empirical construction	39
breast -Walls	27 (8)	Foundation-walls, empirically constructed brick	46
Brick mansonry basic stresses	67	Free-standing walls, empirically constructed brick	55
Bricks cement clay and sand lime	5(9)	Glass blocks, hollow, general requirements for	37
Soil cement	5(12)	Grout for reinforced brickwork	77
Brick walls (see under walls)		Gypsum blocks, general requirements for	36
Building units ,masonry , general for soil cement	34	blocks, requirements for empirical construction	60
empirically constructed	59	mortar	13(14) to (16)
general requirements for	35	Height, total permissible for empirically constructed brick bearing walls.	45
standard	5(9)	Impact tests for walls, including panel- walls.	First schedule
Calculated design of masonry and walling	63-82	Interpretation of certain terms	2
Cavity –walls empirically constructed brick	49	Interpretation of terms	1
general	33	Joints in masonry bond	11
cement used in mansory	5(3)	workmanship	12
Chases and recesses	17(2)to(6) and 39	Lateral or eccentric forces, stresses due to	72
Cold weather construction in	15	Lime used in masonry	5(4)
Columns empirically constructed brick	50	Lintels general	18
empirically constructed plain normal concrete	61	over openings	17(1)
reinforced -brick detailed requirements for	79	Load-bearing surfaces	10
reinforced -concrete	74(4)	Loading of masonry members	9
concrete cast in situ, axil stresses in	70	Loadings and spans of floors and roofs in empirical construction	39
Columns reinforced	74(4)	Loads, concentrated, stresses under	73
in walling	14	Retaining walls empirically constructed brick	56
Lintels reinforced	forth scedule	general	26
no fines empirical construction in	62	of natural stone	58(3)
no fines empirical construction for	38	Roof, thrust from	20
Plain normal empirically constructed walls of	61	Roofs, loadings and spans in empirical construction	39
walls reinforced	74(1)to(3)	Rubble stone for masonry	5(11)
corbelling	21	Sand used in mortar and concrete	5(5)and (6)
cornices	23	Slenderness ratio effective height of columns and walls.	Table XVI
Cross walls	19	effective thickness of stiffened walls	Table XVII
Mansonry (empirically constructed ) blocks	57	general	66
gypsum blocks	60	permissible limits of	Table XIX
natural stone	58	Soil-cement building units general requirements for	35
soil-cement building units	59	requirements for empirical construction of	59
Mansonry (general) block axial stresses in	69	standard building units	5(9)
brick basic stresses for	67	Stiffened walls, factors for	FIFTH SCHEDULE
Buidling -units general requirements for	34	Stiffeners for hollow glass blocks in masonry walls	37(11) and (13)
existing use of	16	Stone for masonry	5(11)
natural stone axial stresses in	71	Stone masonry, natural axial stresses in	71
Materials for empirical construction , minimum requirements for.	42
for reinforced brickwork	76	empirically constructed.	58
not provide for in the bylaws	5(1)	“Storey” dimensions permissible for empirically constructed brick bearing- walls	44
second hand		Strength, compressive and mixing proportions of mortar	13(7)
unspecified walling of		of building units for empirical construction	42
Mortar general	13	of concrete in walling	14(4)
cubes testing of , for compressive strength	third schedule	testing mortar cubes for	third schedule
for glass blocks in masonry walls	37(13)	Stresses axial, in block masonry	69
for reinforced brickwork	77	axial, in cast-in-situ concrete	70
Joints in masonry (workmanship)	12(3)	axial, in natural stone masonry	71
		basic, for brick masonry	67
Natural stone masonry axial stresses in	71	due to eccentric or lateral forces	72
empirically constructed	58	for large slenderness ratios	68
No-fines concrete empirical construction in	62	permissible in reinforced brickwork	78
general requirements for	38	under concentrated loads	73
openings chases and recesses	17	Support of walls	8
overhanging walls	22	Surfaces, load-bearing	10
Panel -walls empirically constructed brick	52(2) to (6)	Tests impact, for walls, including panel-walls	First schedule
general	31	moisture penetration, for walls, artificial rain test.	Second schedule
impact test for	first schedule	of mortar cubes for compressive strength	Third schedule
Parapet-walls empirically constructed brick	53(1) and (2)	Thrust from roof	20
general	27(1)to (6)	Tolerances, dimensions subject to	3
Partition walls empirically constructed brick	54	Unspecified materials, walling of	7
general	32	Veneer, dimensions of empirically con- structed walls carrying heavy	43
Rafters and beams ends of	24	Veneered walls	28
recesses and chases	17( 2) TO (6)	Walls (general) balustrade-	27(7)
Reinforced brick columns detailed requirements for	79	breast-	27(8)
Reinforced brick walls detailed requirements for	80	cavity-	33
Reinforced brick work cover over reinforcement in	81	Cross-	19
general requirements for	75	curtain-, masonry	30
materials for	76	faced	29
miscellaneous requirements for	82	overhanging	22
mortar and grout for	77	panel.	31
permissible stresses in	78	parapet-	27(1) to (6)
Reinforced concrete columns and walls	74	partition..	32
lintels	fourth schedule	reinforced-brick	80
wall-sections between openings in empirically constructed walls	40	reinforced-concrete	74(1) to (3)
walls (empirically constructed ) brick		retaining.	26
above the roof	48	veneered	28
balustrade	53(3)	Water used in masonry or concrete walling	5(7)
basement	46	Weather, cold, construction in	15
bearing 100 mm thick	47	Weatherproof, external walls to be	6
cavity	49	Wing-walls, empirically constructed brick	51
curtain	51(1)	Workmanship	12
foundation	46
free standing	55
panel	52(2)to(6)
parapet	53(1) and (2)
partition	54
retaining	56
wing	51
brick bearing
permissible “storey” dimensions	44
permissible total height	45
concrete no fines	62
plain normal	61

ARRANGEMENT OF SECTIONS

PRELIMINERY

SECTION

1.Interpretation of terms.

2. Interpretation of certain terms.

3.Dimensions subject to tolerances.

PART I
ERECTION OF MASONRY IN BUILDINGS

4. Application of regulations to masonry and concrete walling.

5. Requirements for materials and building-units.

6. External walls to be weatherproof.

7. Walling of unspecified materials.

8. Support of walls.

9. Loading of masonry members.

10. Load-bearing surfaces.

11. Bond.

12. Workmanship.

13. Mortars.

14. Concrete in walling.

15. Construction in cold weather.

16. Use of existing masonry.

17. Openings, chases and recesses.

18. Lintels.

19. Cross-walls.

20. Thrust from roof.

21. Corbelling.

22. Overhanging walls.

23. Cornices.

24. Ends of beams and rafters.

25. Anchorage to joisted timber and precast concrete floors.

26. Retaining-walls: general.

27. Parapet-walls, balustrade-walls and breast- walls.

28.Vennerd wall

29. Faced wall

30. Masonry curtain walls

31. Panel walls

32. Partition walls

34. Cavity walls: general

35.General requirements for hollow masonry walls

36. Genral requirements for soli cement walls.

37. General requirements for hollow glass blocks.

38. General requirements for no-fines concrete.

PART II
GENERAL REQUIREMENTS FOR EMPIRICAL MASONRY CONSTRUCTION

39. Floors, roofs, chases, recesses and panel-walls in empirical construction.

40.Wall-sections between openings in empirically constructed walls.

41.Bearings for beams other than timber in empirical construction.

42. Minimum requirements for materials for empirical construction.

43. Dimensions of empirically constructed walls carrying heavy veneer.

PART III
REQUIREMENTS FOR EMPIRICALLY CONSTRUCTED MASONRY AND CONCRETE A. BRICK BEARING-WALLS

44. Permissible “storey” dimensions for empirically constructed brick bearing-walls.

45.Permissible total height for empirically con- structed solid-brick bearing-walls.

46.Empirically constructed brick foundation- walls and basement-walls.

47.Empirically constructed brick bearing walls 100 millimeters in thickness.

48.Empirically constructed brick walls above the roof.

49. Empirically constructed brick cavity-walls.

50. Empirically constructed brick columns.

51. Empirically constructed brick wing-walls.

B. BRICK NON-BEARING WALLS

52.Empirically constructed brick curtain-walls and panel-walls.

53.Empirically constructed brick parapet-walls and balustrade-walls.

54. Dimensions of empirically constructed brick partition-walls.

55. Dimensions of empirically constructed brick free-standing walls.

56. Dimensions of empirically constructed brick retaining-walls.

C. MASONRY OTHER THAN BRICK

57.Dimensional requirements for empirically constructed masonry of blocks.

58. Requirements for empirically constructed masonry of natural stone.

59.Requirements for empirically constructed masonry of soil-cement building-units.

60.Requirements for empirically constructed masonry of gypsum blocks.

D. CONCRETE

61.Empirically constructed plain normal con- crete walls and columns.

62.Empirical construction in no-fines concrete.

PART IV
CALCULATED DESIGN OF MASONRY AND WALLING
A. GENERAL

63. Application of certain sections.

64.General requirements for design.

65. Dispersion and application of forces.

66. Slenderness ratio.

67. Basic stresses for brick masonry.

68. Stresses for large slenderness ratios.

69. Axial stresses in block masonry.

70.Axial stresses in cast-in-situ concrete.

71.Axial stresses in natural stone masonry.

72. Stresses due to eccentric or lateral forces.

73. Stresses under concentrated loads.

74.Reinforced-concrete walls and columns.

B. SPECIAL REQUIREMENTS FOR REINFORCED BRICKWORK

75.General requirements for reinforced brick- work.

76.Materials for reinforced brickwork.

77.Mortar and grout for reinforced brickwork.

78.Permissible stresses in reinforced brickwork.

79.Detailed requirements for reinforced-brick columns.

80.Detailed requirements for reinforced-brick walls.

81. Cover over reinforcement in reinforced brick- work.

82. Miscellaneous requirements for reinforced brickwork.

FIRST SCHEDULE: Impact tests for walls, including panel-walls.
SECOND SCHEDULE: Moisture penetration test for walls: artificial rain test.
THIRD SCHEDULE: Testing mortar cubes for compressive strength.
FOURTH SCHEDULE: Reinforced-concrete lintels.
FIFTH SCHEDULE: Factors for stiffened walls.

PRELIMINERY

1. INTERPRETATION OF TERMS.

In this Chapter –

“adequate lateral support”, in relation to a wall, means a cross-wall complying with the requirements of section 19, or a structural member which is designed to resist the overturning moments and lateral forces on the wall supported, or a column, buttress, frame or other construction which is, in the opinion of the local authority, adequately to do so;

“admixture” means a material other aggregate, cement or water, added in small quantities during the mixing of concrete to produce some desired modification in one or more of the properties of the concrete;

“aggregate” means a material which is mixed with cement and water to provide bulk in concrete or mortar;

“coarse aggregate” means aggregate complying with the provisions of subsection(8) of section 5;

“fine aggregate” means aggregate having with the provisions of subsections(5) and (6) of section 5;

“light-mass aggregate” means aggregate having a density of not more than 1000 kilograms per cubic meter, measures loose and dry;

“ordinary aggregate” means aggregate other than light-mass aggregate;

“ashlar masonry” means masonry composed of rectangular units of natural or cast stone which have larger exposed face-areas than those of blocks, and have accurately sawn, dressed, cast or squared beds, and are co laid in mortar that the joints not less than 3 millimeters and not more than 8 millimeters in thickness;

“balustrade” means a row of columns crowned by a railing erected along the edge of a balcony or gallery to prevent persons from falling;

“bearing-plate or padstone” means a block of material, placed under the end of a roof-truss, girder or beam, to distribute the load;

“block” means a masonry-unit used in building, and possessing dimensions such that it can be laid only in a non-bonded or stretcher bond pattern;

“cellular blocks” means blocks which are similar to hollow blocks but which have the cavities closed at one end. The solid cross-sectional area of a cellular block shall comprise at least 45 per centum of the total cross-sectional area of that block;

“hollow blocks” means blocks which-

a) contain at least one large hole or cavity of a size such that the solid material in the block constitutes between 48 per centum and 75 per centum of the total volume of the block calculated from its over-all dimensions; or

b) when used in a wall, or in a leaf of a cavity wall, forms internal cavities which have a total area, in the horizontal plane, or more than 25 per centum of the horizontal cross-sectional area of the wall or leaf of the cavity wall;

“solid blocks” means blocks in which the solid material is not less that 75 per centum of the total volume of the block calculated from over all dimensions;

“bond”, as applied to-

a) masonry, means a systematic arrangement of bricks or other building-units in courses, which will enable them to act together as a whole in sustaining loads, and “to bond” has a corresponding meaning;

b) reinforcement, means the shear stress developed at the interface between a reinforcing-bar embedded in concrete or mortar and the surrounding concrete or mortar when an axial force is applied to the bar, the bond stress tending to restrain relative displacement of the bar;

“brick “ means a masonry-unit used in building and possessing dimensions such that it can be laid with the use of any acceptable masonry bonding pattern;

“building-unit” means a brick or block of clay, concrete, calcium silicate, soil-cement or other material, of regular shape or a natural stone or rectangular or irregular shape and size, used in construction of masonry or walling;

“buttress” means a vertical member bonded into a wall for the purpose of giving it lateral support. It resembles a pier but does not extend to the full height of the wall;

“cast stone” means a reconstructed or artificial stone consisting of a mixture of cement and aggregate;

“column” means a vertical load-bearing member measured at right angles to its thickness, does not exceed four times the thickness, and which is not bonded into a wall;

“concrete” means a mixture of cement, aggregate and water, with or without admixtures, which has, or will set to form a hard, cohesive agglomeration;

“light-mass concrete” means concrete having a density less than 1600 kilograms per cubic metre after it has been cured and become air-dry

“no-fines concrete” means concrete containing not more than 10 per centum fines of the total mass of aggregate;

“normal concrete” means concrete containing both fine and coarse aggregate;

“corbel” means a projection built out from the face of a wall to form a load-bearing surface;

“cornice” means a horizontal projection which crowns or finished a wall or any portion of a wall or any other architectural feature;

“empirically constructed” means constructed or intended to be constructed otherwise than in accordance with a design based on calculation of the dimensions required to limit, to the values set out in sections 67 to 74 or in section 78, the stresses which could occur in the masonry or walling, and “empirically construction” shall have a corresponding meaning;

“foundation-footing” means a foundation, not being a pile, supporting a structural member, and usually wider than the structural member;

“height of the wall or column”-

a) “effective height” of a wall or column, means the height of a wall or column assumed for calculating its slenderness ration;

b) “storey-height” of a wall or column, in any storey, means the height of a wall or column measured from the underside of the floor construction of such storey to the under-side of the floor construction immediately above, or when there is no floor above, to the mean height is no floor above, to the mean height of the gable, where the wall is a gable-wall, or to the underside of the roof construction above, whether this be a wall-plate, girder or other framework:

Provided that-

i) where such wall or column is not laterally restrained by the floor, its storey-height shall be measured from the top of the foundation; and

ii) where a column rests centrally on a foundation-wall which is at least 100 millimetres thicker than the column, the storey-height of such column may be measured from the top of such foundation wall;

c) “total height” of a wall or column means heights measured from the top of the foundation -footing girder or slab on which the wall or column rests to the top of the wall or column, whether or not this is above the roof:

Provided that the total height of a gable-wall shall be taken as its mean height:

“length of wall”-

a) “effective length of a wall” means the length of wall assumed for calculating its slenderness ratio;

b) “unbroken length wall” means a length of wall which is not broken into by opening or by chases or recesses which are regarded as openings in terms of section 17;

c) “unsupported length of wall” means the length of the wall measured between the inner faces of adequate lateral support to a free end;

“light-mass construction” means construction in which the walls in any storey and in all storeys above are built entirely of bricks or blocks having density less than 1 600 kilograms per cubic metre of gross volume, or light-mass concrete;

“masonry” means an assembly of non-combustible building-units bonded together;

a) “masonry construction” means construction of masonry or of masonry in combination with other materials;

b) “solid masonry” means masonry in which the building-units are laid with the joints between such units filled with mortar, and without forming cavities between unit;

“masonry-unit”: see “building unit”;

“mortar” means a mixture of cement or lime, or both, with fine aggregate and water;

“pier” means a vertical masonry member bonded into a wall and of the same height as the wall;

“sleep-pier” see “sleeper-wall” or “sleeper-pier”

“restrained”-

a) “a column fully restrained at the top” means a column adequately restrained at the top from movement in position or direction in the plane being considered;

b) “a wall fully restrained at the top” means a wall supporting a solid concrete beams bonded to the wall, or a wall anchored to a precast concrete floor as specified in section 25, or a wall anchored to, and restrained by, roof-trusses or a roof or roof-components, to the satisfaction of the local authority;

c) “a wall moderately restrained at the top” means a wall supporting a timber floor, and anchored to it as specified in section 25, or a wall anchored to, and restrained by, roof-trusses or a roof or roof-components, to the satisfaction of the local authority;

“roof”-

a) “flat roof” means a roof which is not a pitched roof;

b) “heavy roof” means a roof construction including framing, purlins and covering, having a mass of more than 35 kilograms per square meter of horizontal area;

c) “pitched roof” means a roof supported on the external walls of the building;

“rubble”-

a) “random rubble” means masonry composed of roughly shaped or unshaped stones laid without regularity or coursing;

b) “squared rubble” means masonry composed of roughly squared stones arranged to form well-defined horizontal joints;

“sleeper-wall” or “sleeper-pier” means a foundation-wall or pier erected between other foundation-walls or -piers to provide an intermediate support to the lowest floor, and having no corresponding wall or pier directly above it;

“slenderness ratio” means a ratio between the dimensions of a wall or a column, as prescribed by subsections (1) and (2) of section 66, which is used in determining the permissible stresses;

“soil-cement” means a mixture of natural soil and cement compacted, when moist, into a structural material;

“strength” of a building-unit or material means the average strength of a sample of the unit or material measured as specified in the relevant specification or, if there is no specification applicable, as described by testing authority;

“thickness”, applied to a wall, means the actual thickness;

“effective thickness of a wall” means the thickness of a wall assumed for calculating its slenderness ration, as set out in subsections (5) to (10) of section 66;

“veneer” means the facing attached to a veneered wall;

“heavy veneer” means a veneer having a mass of not less than 75 kilograms per square meter, exclusive of the backing-mortar;

“light veneer” means a veneer having mass of less than 75 kilograms per square meter, exclusive of the backing-mortar;

“masonry veneer facing” means a veneer facing composed of masonry building units;

“wall”-

a) “balustrade-wall” means a wall erected in place of a balustrade and serving the same purpose;

b) “basement-wall” means an external wall of a building, enclosing usable floor space of a basement and either wholly or partly below ground-level;

c) “bearing-wall” means a wall which supports any vertical load in addition to its own mass and the mass of a veneer;

d) “cavity-wall” means a wall in the form of two walls(called leaves), built side by side, tied to each other, and separated by a cavity, either left open as an air space or filled with non-loading material;

e) “cross-wall” means an intersecting, bearing or non-bearing wall which may be considered to limit the unsupported length of the wall which it intersects;

f) “curtain-wall” means a non-bearing external masonry wall of a height of one or more than one storey, and which is laterally supported, either by piers or by the vertical and horizontal structural members of the frame of a building, and may be supported over part of its thickness on the slabs or the beams of such frame, and which carries no load other than its own mass and the mass of veneer, if any, and resists and no force other than wind force;

g) “external wall” means a wall separating the interior from the exterior of a building;

h) “faced wall” means a wall in which a facing and a backing are intended to exert a common reaction under load, and are built up simultaneously;

i) “foundation-wall” means a bearing-wall situated below the lowest floor-level;

j) “free-standing wall” means a wall without adequate lateral support at either end or along the top;

k) 32 times its effective thickness;

l) “non-bearing -wall” means a wall which supports no vertical load other than its own mass and the mass of veneer, if any;

m) “panel-wall” means a non-bearing external wall, built between columns, walls or piers, and not exceeding one storey in height;

n) “parapet-wall” means a wall, or that part of a wall, which is entirely above the abutting upper surface of the roof;‘ “internal-wall” means a wall wholly within a building;

o) “masonry breast-wall” means a masonry wall, or portion of such wall, which extends from the floor on which it is built to the sill of a window, and which extends for a length greater than

p) “partition-wall” means a non-bearing internal wall, which is employed solely for the purpose of subdividing any storey of a building of a building into sections;

q) “retaining-wall” means a wall intended to resist the lateral displacement of materials other than liquids;

r) “rubble stone wall” means a wall constructed of random rubble or squared rubble;

s) “skin wall” means a wall protecting a vertical waterproof or damp-proof layer;

t) “sleeper-wall” see “sleeper-wall” or sleeper-pier;

u) “solid wall” means a wall other than a cavity wall;

v) “veneered wall” means a wall which has a facing and a backing which are not intended to exert a common reaction under load;

w) “wing-wall” means a wall which has adequate lateral support at one end only;

“0,3 per centum proof stress” means the tensile stress at which a non-proportional elongation equal to 0,3 per centum of its original length occurs in a material under load.

2.INTEPRETATION OF CERTAIN TERMS.

(1) Wherever “resist” or “sustain” occurs in Chapter, it shall mean resist or sustain, as the case may be, at the stresses permitted in this Chapter.

(2) Wherever “wall” or “walls” occurs, it shall not mean a veneered wall or walls, unless stated to the contrary.

(3) Wherever the thickness of a wall is mentioned, it shall mean the actual thickness, unless the effective thickness is stipulated.

3.DIMENSIONS SUBJECT TO TOLERENCES.

Where the minimum dimension of a wall, a pier or column built of masonry is given in millimetres in this Chapter, then, to make allowance for the tolerance permitted in the size of the standardized building-units, such minimum dimension shall be deemed to be subject to the tolerance set forth in Table I.

TABLE I
DIMENSIONS SUBJECT TO TOLERANCES.

1	2
Dimensions in millimeters	Tolerence (minus) in millimetres
50 65 100 215 or greater	3 3 3 5

4.APPLICATIONS OF REGULATIONS TO MANSORY AND CONCRETE WALLING.

(1) All buildings composed of masonry construction, and all masonry and concrete walls, shall be erected in accordance with the provisions of this section.

(2) All materials and building-units shall comply with the requirements of section 5.

(3) The construction shall be executed in accordance with the general requirements of sections 6 to 38, and, in addition, every part of the construction shall be constructed either-

a) in accordance with the general requirements for empirical construction set out in sections 39 to 43, and the particular requirements for empirical construction set out in sections 44 to 62, applicable to the building-units or materials used; or

b) in accordance with the provisions of sections 63 to 82 for the calculated designed masonry construction:

Provided that-

i) where no calculations are submitted for approval in connexion with the design of any masonry building, or any particular portion of such building, it shall be assumed that such building or portion is intended to comply with the requirements for empirical construction set out in 39 to 62; and

ii) the local authority shall be entitled to require that-

A. walls and piers which support any cantilevered load other than the loads from lintels or from timber floor-joints or ceiling-joists, or from timber rafters or trusses; and

B. any portion of the building which the local authority considers would otherwise be dangerous;

shall either be designed in accordance with the provisions of sections 63 to 82 for the calculated design of masonry construction or be constructed of other materials in accordance with these by-laws.

(4) All walling of materials other than masonry or concrete shall comply with the requirements sect out in section 7 for unspecified materials’

5.REQUIREMENTS FOR MATERIALS AND BUILDING-UNITS.

(1) Materials not provided for in these by-laws.- Subject to the provisions of section 7, building materials not provided for in these by-laws may be used in walling if they comply with the terms of a departure certificate or authorization granted in terms of Part VII of Chapter 2.

(2) Second-hand materials.- Second-hand building materials may not be used unless such materials-

a) are sound; and

b) comply with the requirements of these by-laws; and

c) have been thoroughly cleaned and all adhering other materials which would interfere with their intended function removed.

(3) Cement.- Cement used in masonry shall comply with the requirements of C.A.S. No. A46:

Provided that cement not so complying, but, nevertheless, complying with a specification acceptable to the local authority, may be used.

(4) Lime.- Lime used in masonry shall comply with the requirements of C.A.S. No. A15, Building limes.

(5) Fine aggregate(sand).- Fine aggregate used in mortar shall comply with the requirements os C.A.S. No. A34, Aggregates for concrete, and, in addition-

a) at least 97 per centum of any sample measured by mass, shall pass tthrough a 2,36 millimetre sieve; and

b) the percentage which passes a 75-micrometre sieve when tested in accordance with C.A.S. No. A33, Methods for sampling and testing of minerals aggregates, sands and fillers, shall not exceed 7,5 per centum.

(6) Fine aggregate in concrete shall comply with the requirements of C.A.S. No. A34

(7) Water.- Water for use in masonry or concrete walling shall be clean and free from clay and silt and such amounts of oil, acid, alkali or organic or other matter as, in the opinion of the local authority, will seriously impair the strength and durability of the masonry or walling

(8) Coarse aggregate (stone) .- Coarse aggregate for concrete shall comply with the requirements of C.A.S No. A34.

(9) Standard building units .- The building-units listed in this subsection, when used in construction of buildings, shall comply with the requirements of the standard specification application to the unit concerned, and, in addition, shall comply with the other provisions of this Chapter.

Table

(10) Hollow glass blocks which are 298, 5 millimetres square in elevation, but which in other respects comply with B.S. 1207, shall also be permitted.

(11) Stone for masonry.- Rubble stone shall have a “crushing value” (10 per centum fine test) when tested in accordance with C.A.S No. A33 of not less than 75 kilonewtons.

(12) Soil-cement blocks and bricks.- Soil-cement blocks and bricks, when tested in accordance with C.A.S No. 41, shall comply with the following requirements-

a) the average compressive strength at an age of 28 days shall not be less than 2,8 megapascals;

b) the increase in mass after immersion in water for 24 hours shall not exceed 12 per centum of the dry mass;

c) the linear expansion after immersion in water for 24 hours shall not exceed –

i) 0,05 per centum where, in the opinion of the local authority, cracking of the walls cannot be tolerated;

ii) 0,1 per centum where the blocks or bricks are to be used only in internal walls.

6.EXTERNAL WALLS TO BE WEATHERPROOF.

(1) Every external masonry or concrete wall of a habitable portion of a building shall be capable of withstanding the artificial rain test described in the Second Schedule and shall be-

a) constructed of masonry building-units so as to be at least 200 millimetres thick; or

b) constructed of plain normal concrete at least 200 millimetres thick or reinforced concrete at least 100 millimetres thick, and be treated if necessary; or

c) constructed of no-fines concrete at least 200 millimetres thick; or

d) of such lesser thickness as is permitted by this Chapter for the relevant conditions.

(2) Every external wall of a habitable portion of a building which is not of masonry or concrete shall be weatherproof to the satisfaction of the local authority.

7. WALLING OF UNSPECIFIED MATERIALS.

(1) For the purposes of this section –

“structural damage” shall mean a cracking, spalling or crumbling of the surface of the wall which is readily visible to the naked eye. The fracture of glass in adjacent windows or damage to applied finished shall not be deemed to be structural damage to the wall;

“structural failure” shall mean collapse of the wall or a portion of the wall, or holding of the wall;

“load factor” shall mean the quotient found when that load which causes the first signs of structural damage or structural failure, as the case may be , is divided by the maximum load which the walls are designed to support.

(2) If the walls of a building are to be constructed of materials or building-units not specified in this Chapter, the local authority may call for tests to be conducted, or a report submitted, according to the provisions of Chapter 2, and shall prohibit the use of such materials or units unless the results of the tests demonstrate or the report shows, that such walls comply with such of the following requirements as are, in the opinion of the local authority, applicable to them-

a) when loaded with static loads, the walls shall provide load factors for structural damage and for structural failure not less than those considered satisfactory by the local authority for the material and method of construction concerned;

b) the walls shall withstand the impact test set out in the First Schedule;

c) the deflection, under design load, at the center of walls which are to be plastered shall not exceed 1/360 of the distance between lateral supports, and that of walls which are not to be plastered shall not exceed 1/240 of such distances;

d) when testes for moisture penetration as described in the Second Schedule, walls shall not show visible dampness on the inside surface to the extent specified within a lesser period than set out in the Table in that Schedule for the appropriate conditions;

e) the construction shall be shown to be, or be assessed as being

i) durable; and

ii) stable under variations in load, and under variations in temperature and moisture content which are due to climatic conditions.

8. SUPPORT OF WALLS.

(1) Every wall supported by another all or a structural member shall be supported on a foundation complying with the provisions of Chapter 4, except where the local authority permits the construction of a wall on solid rock after having satisfied itself that the safety of the building will not be endangered by the omission of a foundation.

(2) Except as provided in section 21, no wall shall be allowed to carry a wall thicker than itself, and where, in a building, walls are interrupted by floor-slabs, every wall in each storey shall be located vertically over the wall below, unless full provision is made in the design of such building to support a wall in another position.

(3) Lateral stability to a building as a whole shall be provided by cross-walls or by other means which are to the satisfaction of the local authority.

(4) Empirically constructed walls other than wing-walls, free standing walls and retaining-wall shall have adequate lateral supports at each end.

(5) Empirically constructed external walls shall be either moderately or fully restrained at the top in each storey of a building.

(6) Empirically constructed gable-walls shall be securely anchored to the roof along the top of the gable, and, where necessary, in the opinion of the local authority, provision shall be made at such anchorage to accommodate movement of the roof due to expansion or contraction of the roof.

9. LOADING OF MANSORY MEMBERS.

(1) Where floor-slabs or other slabs or beams are supported by masonry or plain concrete walls, piers or columns, no loads other than the normal surface finishes shall be superimposed upon such supporting members, unless adequate falsework is left or placed under them to carry such superimposed loads without undue deflection, until-

a) such time as the mortar or concrete in such walls, piers or columns has attained the minimum comprehensive strength at 28 days applicable to the class of mortar or concrete employed, as specified in section 13 or 14 respectively; or

b) failing tests to demonstrate such strength referred to in paragraph (a), the following periods have elapsed after the mixing of the mortar or concrete used in the last portion of such walls, piers or columns to the constructed-

i) for class D mortar, 28 days;

ii) for other mortar and concrete made with-

A. Portland cement other than high early strength Portland, 28 days;

B. high early strength Portland, cement, 5 days.

TABLE II

LOADING OF MANSONRY MEMBERS

cementitious materials

1	2
PERIOD	MAXIMUM HEIGHT OF FILL
Less than 3 days 3 days the required period	One third full height as specified in section 46. Full height

“full height” means the height of fill for which a wall acting as a retaining wall has been designed, or, for an empirically con structed foundation or basement wall, means the height specified in section 46 for such brick foundation or basement walls;
† required period” means-
(a) the period required to achieve the design strength of the mortar or concrete or the required strength thereof as set out in section 13 or 14, as the case may be; or
(b) the period set out above in this section for the class of mortar or concrete concerned, before walling supporting slabs or beams is permitted to receive its full load;
whichever is the lesser.

(2) Fill or back-fill shall not be placed against any wall until the period set out in Table II for the relevant maximum height of fill has elapsed after the completion of the wall.

10. LOAD-BEARING SURFACING.

(1) Except as specified in subsection (2), all building-units in masonry construction shall be laid in horizontal courses with their load-bearing surfaces horizontal.

(2) The exceptions to subsection (1) are-

a) stones in random rubble stone walls;

b) stones in natural stone bearing-walls, in which case the beds of the stones shall be approximately level for a minimum distance of 120 millimetres back from the face of the wall;

c) building-units which are permitted to be built to a pattern not forming horizontal courses:

Provided that, for the purposes of section 17, the portion of the wall formed by such units shall be regarded as either an opening or a recess, depending on whether or not such portion extends to a thickness greater than one third of the thickness of the wall;

d) cases where the local authority is satisfied that the design requires the bedding-planes to be inclined to the horizontal.

11. BOND

(1) Except in rubble stone wall, the vertical joints in successive courses in masonry walls shall break joint to the extent of at least a quarter of the length of a building-unit.

(2) Whenever the thickness of a solid wall of bricks or blocks is composed of more than one building-unit, either wall ties shall be built into such a wall to bond it together or a bond shall be
employed which provided a complete course of headers evenly distributed over the face area of the wall.

(3) The clear distance between any header or tie and its nearest neighbor in any direction in any direction shall not exceed the following value-

a) for bricks-

i) 450 millimeters, measured vertically; or

ii) 900 millimeters, measured horizontally;

b) for blocks-

i) 600 millimeters, measured vertically; or

ii) 900 millimeters, measured horizontally.

(4) Where wall-ties are employed to bond together the leaves of a wall, both the ties and their spacing shall comply with the requirements of section 33, whether the leaves are separated by a cavity or not.

(5) Bond-stones.- In walls built of natural stone, bond-stones shall be evenly distributed over the face areas of the wall, and shall be provided on both sides to such an extent that the area of the bond-stones on each side, measured in the plane of the wall, is not less than one-sixth of the face area of the wall.

(6) The bond-stones referred to in subsection (5) shall, in the case of rubble stone walls, which are not retaining-walls, be built into the thickness of the wall to a depth of not less than 320 millimeters or the thickness of the wall, whichever is less, and, in the case of rubble stone retaining-walls, the bond-stones shall extend far enough from each face into the thickness of the wall to overlap the adjacent bond-stones extending from the opposite face by not less than 100 millimeters.

(7) In the case of ashlar masonry walls, bond-stones shall extend throughout the full thickness of the wall.

(8) The maximum distance between adjacent bond-stones on the same side of the wall, center to center, in both the horizontal direction and the vertical stone walls not more than 600 millimeters thick and 750 millimeters for rubble stones walls thicker than 600 millimeters.

(9) Walls shall be properly bonded by a masonry bond to piers and buttress, and, except where walls are bonded to cross-walls by anchors in accordance with section 19, to cross walls.

12. WORKMANSHIP.

(1) Except where the local authority considers it to be unnecessary or inadvisable, all walls shall be plumb, and shall be adequately braced during construction.

(2) Except for concrete and soil-cement building-units, which shall be kept in a dry condition, all masonry building-units shall be thoroughly wetted with water immediately before being laid.

(3) Except in rubble stone walls, and where permitted by the local authority, all masonry building -units shall be laid in mortar joints shall be filled, and shall be not less than 5 millimetres and not more than 20 millimetres in thickness.

(4) No portion of a masonry wall shall be built up during building operations more than 1 metre above the top of any other portion of such wall.

13.MORTARS.

(1) Mortars: classification.-Except where gypsum is required by section 36, or where another mortar is permitted under subsection (8) , mortar shall be one of the classes specified in Table III to subsection (7), and shall otherwise comply with the requirements of this section relating to its class. The requirements of this section relating to its class. The use of “artificial plasticisers” may be employees as an additive to cement mortars with the approval of the local authority.

(2) Composition: class A.- Class A mortar shall be composed of Portland cement together with fine aggregate in the proportions specified in subsection (7) . Plastic hydrated lime to the extent of no
more than 25 per centum of the dry cement by volume may be added to increase the workability, Such mortar shall be used within 60 minutes of the time when the cement was added to the mix.

(3) Composition: classes B and C.- Classes B and C mortars shall be composed of Portland cement together with fine aggregate in the proportions specified in subsection (7), and may include either lime-putty or hydrated lime.

(4) If normal lime is used in class B or class C mortar-

a) the mortar shall not be used as before it has been allowed to mature for at least 24 hours after the lime has been mixed with the fine aggregate; and

b) the mortar shall be used within 60 minutes of the time when the cement was added to the mix.

(5) Composition: class D.- Class D mortar shall be composed of lime-putty or hydrated lime and fine aggregate in the proportions specified in subsection (7), and Portland cement to the extent of not more than 25 per centum by volume of the dry lime may be added to increase the strength.

(6) If normal lime is used in class D mortar, the mortar shall be allowed to mature before being used for at least 24 hours after the lime has been mixed with the fine aggregate.

(7) Proportions and required strength mortars.- When tested in accordance with the Third Schedule, mortars of the classes specified in Table III shall have the minimum compressive strength shown in that Table.

TABLE III

MIXING PROPORTIONS AND STRENGTHS OF MORTARS

1	2	3	4	5
	LIMITING PROPORTIONS MEASURED BY VOLUME			Minimum required compressive strength in megapascals (at 28 days)
Class	cement	lime	fine aggregate
A B C D	1 1 1 0.25	0-0.25 0-1.25 0-2.5 1	not more than 4 not more than 6 not more than 9 not more than 4.5	14.0 6.5 2.0 0.6

(8) Special mortars.- Mortars other than those specified in subsection (1), such as hydraulic lime mortar, may be used where tests have shown them to be satisfactory with regard to strength, soundness and consistency, to the satisfaction of the local authority.

(9) Permitted use of mortars.- Except where the provisions of this Chapter require otherwise, mortars shall be used only as specified in subsections (10) to (13):

Provided that mortar classes of a higher required compressive strength may be used for the purposes permitted for a class of lower required strength, but not vice versa.

(10)Class D mortar may be used-

a) in a bearing-wall or pier in a single storey building, or in the topmost storey of a building:

Provided that-

i) such wall shall not be a cavity-wall or a rubble stone wall; and

ii) such mortar shall not be used in a portion of the wall which is either above the surface of the roof or below the damp-proof course near ground-level or which is exposed to continual dampness;

b) in a partition-wall or a curtain-wall or a panel-wall, but not in a retaining-wall or a balustrade-wall or a free-standing wall.

(11) Class C mortar may be used-

a) in a bearing-wall pier:

Provided that such mortar shall not be used in a portion of the wall which is either above the surface of the roof or below the damp-roof course near ground-level, or which is exposed to severe conditions of continual dampness;

b) in a partition-wall or curtain-wall or a panel-wall, but not in a retaining wall or a balustrade-wall.

(12) Class B mortar may be used in bearing-walls, piers and columns, and in partition-walls, curtain-walls, panel-walls, free-standing walls and wing-walls.

(13) Class A mortar may be used in any masonry construction.

(14) Gypsum mortar.- Gypsum mortar shall composed of gypsum and fine aggregate, the volume of which shall not exceed twice that of the gypsum.

(15) In no case shall gypsum be mixed with Portland cement, or be allowed to come into contact with Portland cement or the products thereof within seven days of the time when Portland cement was mixed with water.

(16) Gypsum mortar shall not be used as mortar with building-units other than gypsum or glass blocks:

Provided that it may be used as internal plaster with any mature building units.

14. CONCRETE IN WALLING.

(1) Concrete used in walls, piers and columns, and in foundations for them, shall except where otherwise specified, be made, placed and cured in accordance with the requirements of the appropriate Central African, and, in addition, shall comply with requirements of the of the following subsections.

(2) Normal concrete, other than light-mass concrete used in the construction of load-bearing members, shall be mixed in the proportions of one part of cement to not more than nine parts in all, when measured by volume and counted separately before mixed, of fine and coarse aggregate, and such concrete used in the construction of non-load-bearing members shall be mixed in the proportions of one part of cement to not more than than twelve parts in all of fine and coarse aggregate, measured in the same way.

(3) Light-mass concrete and no-fines concrete used in bearing-walls shall be made, placed and cured in accordance with the requirements for controlled concrete in Chapter 3.

(4) When tested in accordance with the provisions of Chapter 3, the various classes of concrete shall have a cube strength at an age of 28 days of not less than the following-

a) normal concrete, with ordinary aggregate-

i) for load-bearing members, 14 mega pascals;

ii) for non-load-bearing members, 7 mega pascals;

b) light-mass normal concrete, 3,5 mega pascals;

c) no-fines concrete employing ordinary aggregate, 2,45 mega pascals;

d) no-fines concrete employing light-mass aggregate, 1,75 mega pascals.

1Note that further requirements are set out as follows-
for reinforced-concrete walls and columns, in section 74;
for reinforced-concrete lintels, in section 18;
for unreinforced-concrete walls, in sections 61, 62 and 70.

15.CONSTRUCTION IN COLD WEATHER.

No masonry construction shall take place when the temperature at the site of work is below-

a) 2 degrees Celsius at a time when the temperature is rising; or

b) 5 degrees Celsius at a time when the temperature is falling.

16.USE OF EXISTING MANSONRY .

(1) an existing masonry wall, pier or column may be used in the construction of a building, and in the repair, alteration or enlargement of a building, if it complies with the requirements of these by-laws.

(2) an existing masonry wall which is structurally sound which is of insufficient thickness for its proposed use may be made thicker by the addition of material similar to that of the existing wall, laid in mortar of the required proportions, if the foundations for the completed structure comply with these by-laws.

(3) The additions or linings referred to in subsection(2) shall be thoroughly bonded to the existing masonry by toothings bonded 100 millimeters deep or the full thickness of the lining. Whichever is lesser, into the new masonry, and at least 100 millimeters into the existing masonry.

(4) The toothings referred to in subsection (3) shall be distributed uniformly throughout the area of the additions to the wall, and shall have an aggregate vertical cross-sectional area not less than 15 per centum of the total area of that part of the wall thickened by lining.

(5) Plaster, or adherent coatings which might impair the adhesion shall be stripped off any wall-surface against which a lining is to be built, and the whole of such masonry surface shall be created before the construction of the lining is commenced.

17. OPENINGS, CHASES AND RECESSES.

(1) Lintels and arches over openings2..-The portion of a masonry or concrete wall above an opening shall be provided with a lintel constructed as an arch, and shall comply with requirements as set out in Chapter 3 or section 18.

(2) Chases and recesses.- Where horizontal chases or recesses are cut to a depth greater than one-fifth of the thickness of the wall, or leaf of the cavity-wall, concerned, or are built into the wall to a depth grater than one-third of such thickness, or where chases or recesses are cut or formed on both sides of particular length of wall, then such chases of section 40, and shall be bridged over accordingly.

(3) Decorative timber or timber nailing-strips may be set into masonry or concrete walls, piers or columns, but such timber is regarded as a recess if the depth of building is less than one-third of the thickness of the wall, and as an opening if it is more than one-third.

(4) No length of wall between openings which is less than 230 millimetres in length shall have any openings, recess or chase out into it unless supported to the approval of the local authority:

Provided that this provision shall not be constructed as preventing such an opening, recess or chase being built in as construction proceeds in such a length of wall.

(5) Every chase shall be filled solidly around services with mortar not weaker than class B, and the filling shall be allowed to harden before any plastering is done. The surface of the chase shall be wetted down and the mortar made dry around service-boxes shall be similarly filled with mortar not weaker than class B.

(6) Wall not to be endangered by openings, chases or recesses.- The number, size, position and manner of forming of openings, recesses and chases in any masonry or concrete wall such that such wall, pier or column is not, in the opinion of the local authority, thereby rendering unsafe.

18. LINTELS.

(1) Reinforced concrete lintels may:-

a) be constructed in accordance with the requirement set out in the Fourth schedule: or

b) be proprietary pre-cast lintels of approved manufacture.

(2) Lintels of types other than that specified in subsection (1) may be used to the design and construction being approved by the local authority.3

2 Where required by the provisions of Chapter 11, lintels should have the fire-resistance rating there specified for structural members.

3Reinforced brick lintels, if designed and constructed to accord with the provisions of NBR1 Information sheet X/BOU 2-29, dated June 1975, issued by the National Building Research Institute of South Africa, shall be deemed to satisfy the requirements of the local authority.

19. CROSS WALLS.

Every cross-wall shall comply with the follow- ing requirements-
(a) it shall be built at an angle of not less than
40 degrees with the wall which it intersects;
Where required by the provisions of Chapter 11, lintels should have the fire-resistance rating there specified for structural members.
“Reinforced brick lintels, if designed and constructed to accord with the provisions of NBRI Information Sheet X/BOU 2-29, dated June, 1975, issued by the National Building Re- search Institute of South Africa, shall be deemed to satisfy the requirements of the local authority.

(b) it shall be carried up to the full-storey height of the wall which it supports;
(c) if a gable is to be supported laterally by a cross-wall, the wall may be raked up to the gable in the form of a buttress commencing from the top or wall-plate level of the wall: Provided that-
(i) the angle of the rake is not greater than 45 degrees to the horizontal; and (ii) the height of the buttress shall be designed to provide the maximum necessary support to the gable at a point where the cross-wall meets the gable-face; and
(iii) the cross-wall and the buttress shall be bonded to the gable.
(d) its over-all thickness shall be not less than 200 millimeters for solid walls or 280 millimeters for cavity-walls:
Provided that, in a single-storey building or the topmost storey of a building, the over- all thickness may be 100 millimeters for solid walls or 200 millimeters for cavity-walls; (e) the unbroken length of the cross-wall, adjoining the supported wall, shall be not
less than-
(i) for cross-walls less than 200 millimeters in thickness, one-third of the height of the walls; and
(ii) for cross-walls not less than 200 millimeters in thickness, one-quarter of the height of the walls;
(f) the length of cross-walls which are wing- walls or portions of intersecting walls shall be measured from the nearer face of the supported wall, excluding the thickness of the latter;

(g) where a cross-wall is bonded into two return walls, extending in opposite directions from the two ends of the cross-wall, the length of the cross-wall shall include the thickness of the two return walls;
(h) a cross-wall shall be deemed to be properly bonded to a cavity-wall if it is bonded to one leaf only:
(i) a cross-wall which is a cavity-wall shall have both leaves bonded to the wall which it, supports;
(j) when a wall and the cross-wall supporting it are built up separately-
(i) the wall and cross-wall shall be bonded together by regular and evenly spaced toothing’s comprising half the height of the walls, so as to provide a bond of not less than 100 millimeters; or
(ii) metal anchors of minimum cross- section 3 x 32 millimeters or of equivalent cross-sectional area and at least 450 millimeters in length, with ends bent up at least 50 millimeters, shall be provided at vertical intervals not exceeding one meter, and such anchors shall be protected against corrosion.

20. THRUST FROM THE ROOF.

(1) Where a roof exerts lateral thrust on supporting walls, piers or columns which results wholly or partly from dead, the walls, piers or columns shall be designed in accordance with requirements of sections 63 to 82.

(2) If such thrust results from superimposed load only, then no such design shall be necessary on that account.

21.CORBELLING.

(1) Walls less than 215 millimetres in thickness shall not be corbelled, nor, in a cavity-wall, shall a leaf less than 215 millimetres in thickness corbelled :

Provided that nothing in this section shall be construed as preventing walls overhanging their supports in accordance with the provision of section 22.

(2) In a single-storey dwelling-house or dwelling-units, a 215 millimetres solid foundation-wall may be corbelled to support a cavity-wall of a maximum over-all thickness of 300 millimetres:

Provided that –

i) the total projection does not exceed 50 millimetres on either side;

ii) the foundation-wall is corbelled out to provide a solid bearing of the full total thickness of the cavity-wall in accordance with section 22;

(3) Except as may be permitted in the requirements for constructions specified in Chapter 22, and as set out in this section, no corbel shall be used to support wall.

(4) No corbel from a masonry less than 330 millimetres in thickness shall be used to support a floor or a roof, except that, in dwellings-houses or dwelling-units only, wall not less than 215 millimetres in thickness may be corbelled to support a timber floor.

(5) Walls built of hollow building-units shall not be corbelled.

22. OVERHANGING WALLS.

Walls may overhang their supports only in the case of a single-storey building or the top storey of a building:

Provided that-

i) the base of a solid wall or of the leaf of a cavity-wall shall not overhang its support to a total extent greater than one-third of its thickness, whether the overhang occurs on one or both sides;

ii) a cavity-wall which is built up a solid wall, properly bonded, to a height above its base of not less than its total thickness, shall not overhang its support to a total extent greater than one-quarter of its total thickness;

iii) the support for the overhanging portion of the solidly built-up base of a cavity-wall shall be a corbel, in which each individual course projects beyond the course below by not more than one-third of the height of the course

or, alternatively, shall be a further portion of solid wall, properly bonded, equal in height of a corbel constructed as described in this section.

23. CORNICES.

The center of gravity of every cornice, whether surmounted by masonry or not, shall fall within the middle third of the thickness of the wall below, unless adequate structural support is provided.

24. END OF BEAMS AND RAFTERS.

(1) Solid bearing-walls less than 215 millimeters in thickness, and cavity bearing-walls having both leaves not thicker than 100 millimeters each, shall not be broken into, subsequent to being built, for the insertion of beams or rafters, except with the written approval of the local authority.

(2) Timber beams and joists supported upon masonry shall have a bearing at least 75 millimeters in length at each point of support.

(3) beans and girders, other than loose of timber, in empirically constructed buildings shall have an area of bearing masonry in accordance with the provisions of section 41.

(4) In buildings not empirically constructed, the bearings shall be such as yo prevent stresses in the masonry exceeding those specified in sections 63 to 73 or in section 78.

25. ANCHORAGE TO JOISTED TIMBER AND PRECAST CONCRETE FLOORS.

(1) Where the joisted timber or precast concrete floors are to be regarded as providing lateral restraint to the supporting-wall at the level of the floor, anchors shall be provided to secure the bearers or joists or flooring-units to the wall at distances apart not greater than 1,8 metres, measured along the wall extending through two storeys, or not greater than 1,2 metres for a wall extending through more than two storeys.

(2) The anchors referred to in subsection (1) shall-

a) be of corrosion-resistant metal or protected metal; and

b) have a cross-section of not less than millimetres, or equivalent area; and

c) have a length of not less than 600 millimetres; and

d) be securely fastened to timber joists by screws, nails or bolts; and

e) be anchored in the wall by means of split and upset ends, or by other effective means.

(3) Where the restrained wall is parallel to timber joists, such anchors shall be secured to not less than three joists with fastenings which can develop the full strength of the anchor, and herring-bone or solid strutting of cross-section not less that 38 x 38 millimetres shall be provided between three joists nearest the wall.

(4) The strutting referred to in subsection (3) shall be at right angle to the joists and opposite the wall-anchor.

(5) Where such a wall is parallel to precast flooring-units –

a) the anchors shall be carried over at least three supporting units or extend at least 750 millimetres from the wall; and

b) the ends shall be turned down at least 50 millimetres between units or into in situ concrete ribs; and

c) such anchors shall be protected from corrosion by a dense cement-mortar topping not less than 25 millimetres in thickness.

(6) In the case of cavity-walls, such anchors need to be fixed in the nearer leaf only.

26. RETAINING-WALLS: GENERAL.

(1) Every retaining-wall which does not comply with the provisions of section 46 or 46 shall be designed in accordance with the requirements of section 63 to 82.

(2) A French drain or other efficient form of drain shall be provided behind a wall over 400 millimetres in height, intended to act as a retaining -wall, to drain fill, and steps shall be taken, where needed, to prevent erosion of the fill near the drain.

(3) weep-holes to carry off water from such drain shall be provided through such a wall, of size and spacings suitable in the opinion of the local authority, for the soil conditions prevailing.

(4) A surface-drain shall be provided in front of the retaining-wall to dispose of water from the weep-holes.

(5) Notwithstanding the provisions of subsections (2) to (4), the local authority may approve other similarly adequate means to drain the fill behind the retaining-wall, and to dispose the water so drained off.

27. PARAPET-WALLS, BALUSTARDE-WALLS AND BREAST-WALLS.

(1) Masonry parapet-walls shall be designed in accordance with the requirements of section 63 to 82, unless they are bonded into return walls bonded to the structural frame of the building, or are tied to reinforced-concrete or reinforced-brick columns, or bonded into reinforced-brick piers.

(2) Reinforced-concrete columns shall be constructed in accordance with the provisions of Chapter 3.

(3) Reinforced-brick columns and piers shall comply with the requirements of sections 75 to 82.

(4) The return walls, columns and piers referred to in subsection (1) shall be no farther apart, center to center, than-

a) 7,5 meters for parapet-walls 215 millimeters in thickness; or

b) 4,5 meters for parapet-walls 100 millimeters in thickness

(5) If masonry parapet-walls are constructed on a concrete slab, they shall be provided with expansion joists at distances apart not exceeding 7,5 meters, and if such walls are bonded to piers, the expansion joints shall bisect the piers.

(6) Empirically constructed parapet-walls shall be constructed in accordance with section 53, and, if such walls act as balustrades, they shall comply with the requirements of subsection (7).

(7) Masonry balustrade-walls shall be designed in accordance of sections 63 to 82, unless tied columns or bonded into return walls or piers, and shall be provided, where necessary, with expansion joints as required for parapet-walls by subsection (5):

Provided that the return walls, columns or piers shall be not farther apart than-

a) 6,6 meters for a wall 215 millimeters in thickness; or

b) 4,05 meters for a wall 100 millimeters in thickness;

and the expansion joints shall not be farther apart than 8,1 meters.

Attention is drawn to the requirements for balustrades in Chapters 11 and 12.

28. VENEERED WALLS.

(1) Materials used as veneers shall have a thickness not less than stated in S.A.B.S. 073 except where the local authority permits a local diminution of thickness such as required to permit the support of veneer on a rib, slab or beam.

(2) Materials used for masonry veneer shall be sound and durable and free from fissures which might affect their durability, and, in the opinion of the local authority, have a record of satisfactory use under conditions comparable to those of their intended use, or be proven durable under test conditions comparable to exposure in the place of their intended use.

(3) No materials other than those referred to in S.A.B.S. 073 shall be used for anchors unless they are tested and shown to be satisfactory, in the opinion of the local authority.

(4) The thickness of the veneer shall not be included in the required thickness of veneered walls. The thickness of the backing and the height of the veneered walls shall be-

a) for empirically constructed walls, as set out in sections 42 and 43;

b) for designed walls, as required by sections 63 to 82

Provided that due allowance shall be made for the additional load caused by the mass of the veneer, and that effective thickness of the wall is derived from the thickness of the backing alone.

(5) Veneer faces shall be designed and constructed in accordance with the requirements of S.A.B.S 073, unless calculations of stresses are submitted to, and approved by the local authority.

(6) Heavy masonry veneer facings shall be tied into a backing of masonry or other non-combustible material5 which is, in the opinion of the local authority of adequate stability and rigidity.

(7) Light masonry veneer facings shall be provided with supports at the heads of all openings, except where the omission is specifically approved by local authority.

(8) The use of veneers shall otherwise comply with the requirements of S.A.B.S. 073.6

5 Attention is drawn to the fact that masonry veneer facings which are fixed direct to the structural framework must comply with the requirements for curtain-walls or panel-walls(see definition)

6The sealing-coat and mastic should preferably be from the same manufacturer.

29. FACED WALLS.

(1) For empirically constructed faced walls the building-units and mortar comprising both facing and backing shall comply with the requirements of section 42.

(2) No materials other than those referred to in S.A.B.S. 073 shall be used for anchors unless they are tested and shown to be satisfactory, in the opinion of the local authority.

(3) When the thickness of a faced wall is derived from calculation, the permissible stresses applicable to the building-units and mortar forming the facing or those forming the backing (whichever gives the greater thickness of wall) shall be applied to the whole of the wall.

(4)When the thickness of such wall is taken from the requirements of this Chapter for empirically constructed walls, such thickness shall be that applicable to the building-units and mortar comprising the backing or to those compromising the backing or those comparing the facing, whichever building-units and mortar require the greater thickness.

(5) The use of facings in faced walls shall otherwise comply with the requirements of S.A.B.S 073.

30.MASONRY CURTAINWALLS.

(1) Masonry curtain-walls shall be tied to the horizontal and vertical structural members of the building frame by means of corrosion-resistant anchors, which are secured to such members with fastenings which develop the full strength of the fastenings which develop the full strength of the anchor, and there shall be at least anchor for each 0,8 square metre or remaining portion thereof of face-area of the curtain wall, and anchors shall be evenly spaced along such members.

(2) The anchors referred to in subsection (1) shall have the minimum dimensions set out in Table IV.

TABLE IV
ANCHORS FOR CURTAIN-WALLS

1	2	3
	Minimum size in millimeters
material	wire anchors (diameter)	strip anchors (thickness x width)
copper hard drawn…….. annealed……….. brass 70% copper 30% zinc annealed……… half hard ……. stainless steel mild steel, galvanised or otherwise adequetly protected malleable cast iron adequetly protected	4,00 5,60 – – 11,20 11,20	– 1,60x 32 1,60x 25 1,20x 16 1,20x 16 – – 5 x20 5 x20

(3) Materials not mentioned in Table IV shall not be used for anchors unless they are tested, and the local authority is of the opinion that they are equally satisfactory to those mentioned in Table IV:

Provided that the curtain-wall may be fixed to the frame by some other means acceptable to the local authority.

31. PANEL-WALLS.

(1) Panel-walls shall be secured to the structural frame at both ends and, where required by section 52, along their tops, so as to prevent lateral movement, by means of corrosion-resistant anchors, each of cross-sectional area of not less than 60 square millimetres.

(2) There shall be one anchor for each 0,5 square metre or remaining part thereof of the face area of the panel-wall, and anchors shall be evenly spaced along such edges of the wall as are anchored by another approved method.

(3) Panel-walls which overhang their supports shall comply with the requirements of section 22.

32. PARTITION -WALLS.

Every partition-wall shall either be bonded or anchored to cross-walls at both ends as required by section 8 or 19, or shall be so fixed at one end only and at the other be fixed to a framework which, in the opinion of the local authority, provided an adequate lateral support.

33.CAVITY-WALLS : GENERAL.

(1) Cavity-walls may be used for load bearing purposed, subject to the conditions specified in this section.

(2) The inner and outer leaves of the shall be separated by a cavity which shall, throughout, be of a width of not less than 50 and not more than 75 millimetres, and, where the damp-proof layer does not bridge the cavity, shall, throughout extend at least 150 millimetres below damp-proof level, but in no case below finished ground-level.

(3) The inner and outer leaves of the wall shall be securely tied to each other with bonding-ties in accordance with the following paragraphs-

a) such ties shall be placed at distances apart not exceeding 1 metre horizontally and 450 millimetres vertically;

b) within 150 millimetres of the sides of every opening, there shall be one tie to every 300 millimetres of height of such opening if the leaves are not connected by a bonded jamb;

c) the ties shall be butterfly type or vertical twist type, and shall conform to S.A.B.S. 28. Metal ties for cavity walls

(4) During construction, the cavity shall be cleared regularly of mortar droppings or other debris, and provision shall be made to drain the cavity.

(5) The cavity shall be sealed at the top of the wall, and, if the wall in the storey above overhangs the wall beneath, the lower wall shall be sealed at its top by solid walling of a height of not less tha 215 millimetres and of a thickness, measured in the direction of the thickness of the wall, of not less than 215 millimetres.

(6) where the wall supports a floor on which the superimposed load exceeds 250 kilograms per square metre of floor area, the floor-loads shall be deemed to be carried entirely on one leaf of the wall, which shall be designed and constructed to carry such load.

(7) The external leaf of a load-bearing cavity-wall shall be supported by floor-slabs carried through both leaves of the wall at vertical intervals not greater than 12 meters or three Storeys, whichever is the lesser; in such a case, the internal leaf of the wall below such a slab shall be designed to carry the loads coming from both leaves of the wall above such slab.

34. GENERAL REQUIREMENTS FOR HOLLOW MANSONRY UNITS.

Where hollow masonry building-units are used in masonry construction, the following requirements shall be complied with-

a) where roofs, floors or beams bear directly on walls, piers or columns, either-

i) all cavities in the top course of the building -units in the supporting member shall be completely filled with mortar of the same class as that used for laying the units; or

ii) the top course in the supporting member shall be of sold building-units not less than 100 millimetres in height;

b) where a wall of hollow units is decreased in thickness at any particular height, the top course of units of the thicker section shall either be completely filled with mortar of the same class as that used in laying the units or be of solid units not less than 100 millimetres in height;

c) in no case shall a foundation-wall of hollow units be corbelled to carry a thicker wall;

d) in no case shall a wall of hollow units supports a veneer, except in accordance with S.A.B.S. 073;

e) where mortar is spread on the cross-webs, a clear space, free of mortar, not less than 25 millimetres in width, may be left at the centre of each such web to prevent the passage of moisture through the joint.

35. GENERAL REQUIREMENTS FOR SOIL-CEMENT UNITS.

(1)Soil-cement building-units shall not be use in masonry in the following cases-

a) in basement-walls or foundation-walls;

b) in lintels and arches;

c) in walls exposed, in the opinion of the local authority, to prolonged rainfall or continual dampness;

d) in veneered walls.

(2) Soil-cement blocks and soil-cement bricks may be used in bearing-walls other than those set out in subsection (1) if such walls are designed in accordance with the provisions of sections 63 to 82.

(3) In walls not designed in accordance with the provisions of sections 63 to 82-

a) soil-cement blocks may be used only in single-storey and double-storey buildings; and

b) soil-cement bricks may be used only in single-storey buildings.

(4) Two-storey buildings built of soil-cement block shall be strengthened by a concrete-belt course which is-

a) not less than 150 millimetres in depth, and of the full width and length of the walls; and

b) reinforced with two 10 millimetre-diameter mild-steel rods, or reinforcement of equivalent cross-sectional area; and

c) of Grade 20; and

d) situated immediately under the upper-floor joists;

and which shall extend continuously around the building.

(5) Conduits and piped, other than water-pipes, plumbing and drain-pipes, may be housed in chases in soil-cement walls:

Provided that, if such conduits or pipes are of an external diameter greater than 25 millimetres, such chases shall not be cut, but shall be built in as the work proceeds, and the wall shall be thickened around the chase to the extent of the dimensions of the chase.

36. GENERAL REQUIREMENTS FOR GYPSUM BLOCKS.

(1) Gypsum blocks shall be used only in non-loading-bearing, interior walls which are not, in the opinion of the local authority, exposed to continuous dampness.

(2) Gypsum blocks shall not be laid in any mortar other than gypsum mortar, and shall not be allowed to come into contact with Portland cement and Portland cement products within seven days after the cement was mixed with water.

37. GENERAL REQUIREMENTS FOR HOLLOW GLASS BLOCKS.

(1) Hollow glass blocks used in masonry walls shall be regarded as forming non-load bearing panels in such walls, which, for the purposes of section 1 shall be regarded as openings, and shall comply with the requirements of the following subsections.

(2) If the panel of hollow glass blocks exceed six metres in height or breadth, or 12 square metres in area, then intermediate stiffeners, in accordance with the requirements if subsections (11) and (12), shall be provided so as to limit the area of blocks between the supports afforded by such stiffeners or by the edges of the panel to not more than 12 square metres.

(3) The distance apart of such parallel support shall not exceed sic metres.

(4) In exterior walls, the panels shall be accommodated in masonry or other recesses, and, in interior walls, in recesses or rebates at the head and jambs of the opening, and, on these three sides, clearance joints not less than 12 millimetres in width shall be provided in order to keep the panel free of the surrounding wall.

(5) The clearance joints shall be filled with non-hardening compound or with glass fibre pointed with a non-hardening compound.

(6) Horizontal reinforcement for the panel shall be provided in the form of corrosion-resistant metal strips or mesh not less than 25 millimetres and not more than 65 millimetres in width, which shall be built into the horizontal mortar joints as follows-

a) for panels not longer than 4,5 metres, every fifth course;

b) for panels not longer than 5,1 metres, every fourth course;

c) for panels not longer than 6 metres, every third course;

but the vertical interval between reinforcements shall not exceed 1 metre.

(7) Where of steel, reinforcing strips shall be not less than i millimetre, and steel reinforcing mesh shall consist of not less than two longitudinal wires, each not less than 3,55 millimetres, welded into the longitudinal wires at interval not exceeding 200 millimetres.

(8) Where other shapes or metals are used, the tensile strength shall not be less than that of such steel reinforcement.

(9) Where the reinforcing-strips are of steel-wire mesh, they shall continue throughout the length of the horizontal mortar joints, and be turned up in the expansion joints not less than 75 millimetres, and be secured to the frame of the building or to a stiffener by means of nails, bolts or wire located at least 40 millimetres above the horizontal joint.

(10) The fastening shall be capable of developing the full strength of such reinforcing-strip.

(11) Stiffeners.-Stiffeners shall be of sufficient strength to withstand the bending moments and shearing forces which may be caused by dead loads and wind forces on the glass-block panel at stresses not exceeding 20 per centum of the minimum specified tensile strength of the materials concerned.

(12) stiffeners of steel shall be protected against corrosion by painting or by some other method of an efficiency satisfactory to the local authority.

(13) Mortar for glass blocks.- Mortar used with glass blocks shall mixed in the proportions of 1 part of cement to 1 part of hydrated lime or lime-putty, to not less than 4 and not more than 6 parts of sands by volume.

38. GENERAL REQUIREMENTS FOR NO-FINES CONCRETE .

(1) The use of no-fines concrete for walling shall be subject to the requirements of the following subsections.

(2) No0-fines concrete shall be used only in the bearing-walls not exceeding two storeys in height, in which the superimposed loads on suspended floors do not exceed 250 kilograms per square metre or of dwelling-houses of not more than three storeys, and in panel-walls, partition-walls and wing-walls.

(3) No-fines concrete shall not be used in any foundation wall or basement-wall, and no-fines concrete walls shall not be veneered except in in accordance with S.A.B.S. 073

(4) Holes, chases and recesses shall all be formed during construction of the wall, and shall not be cut afterwards.

(5) All exteriors surfaces shall be rendered with rendering at least 12 millimetres thick, which shall be mixed in proportions specified for class B or class C mortar in subsection (7) of section 13, and weep-holes at least 10 millimetres in diameter shall be formed in such rendering just above the damp-proof course and not farther apart than 1,5 metres.

(6) The bearing-surfaces which are to support timber or steel joists or precast concrete beams or slabs shall be levelled off to a smooth surface with class A mortar of a thickness of not less than 20 millimetres at the thinnest point, and the joists, beams or slabs shall bear solidly on such mortar surface at all points of the bearing-area.

(7) All reinforcement-rods used in the walls shall first be derusted and all loose mill-scale removed, and then be protected against corrosion by a coating of cement slurry which shall be allowed to harden before the concrete is cast around the rods

(8) There shall be no raking construction joints in the walls.

(9) The concrete shall be mixed and placed as specified in Chapter 3:

Provided that the concrete shall not be vibrated , but shall be rodded sufficiently to place it in its correct position.

(10) Flues in no-fines concrete walling shall be surrounded by normal, plain concrete not less than 25 millimetres in thickness, and no fines concrete not less than 150 millimetres in thickness shall be placed around the normal concrete.

39. FLOORS, ROOFS, CHASES, RECESSES AND PANEL-WALLS IN EMPIRICAL CONSTRUCTION.

(1) The provisions of this section shall apply in empirically constructed buildings of masonry.

(2) Suspended floors other than of timber, or structural units comprising such floors, shall not exceed in span the figure set out column 3 of Table V for the superimposed load per square metre
for which the floor is designed set out in column 2 of floors in such buildings shall not exceed 250 kilograms per square metre.

TABLE V
MAXIMUM WIDTH OF SUSPENDED FLOOR SLABS FOR EMPIRICAL CONSTRUCTION

1	2	3
class of loading	minimum superimposed load on floor Kilograms per square meter	maximum span of floor or floor units meters
140	140	6,0
190	190	5,1
240	240	4,2

(3) The span of roof-trusses or girders shall not exceed 12 metres and, where such exceeds 10, 5 metres, the mass of the roof-covering, together with the purlins and framing, shall not exceed 35 kilograms per square metre of the horizontal area.

(4) Roofs shall be so constructed that no horizontal or inclined force other than that due to wind force is transmitted to walls.

(5) No recess shall be cut or formed so as to occupy a horizontal length of wall between the two vertical lines drawn through the adjacent sides of any two adjacent openings greater than one quarter of the horizontal distance between such lines.

(6) No opening, and no chase or recess regarded as an opening in terms of subsection(2) of section 17, shall be made in any panel-wall unless such a panel-wall is fixed along its top in accordance with the requirements of section 52.

7Attention is drawn to the fact that the walls designed in accordance with sections 63 to 82 do not also have to comply with the requirements for empirically constructed walls included Tables V to XVI.

40. WALL-SECTIONS BETWEEN OPENINGS IN EMPIRICALLY CONSTRUCTED WALLS.

(1) The number size or position of openings in a wall, including chases or recesses regarded as openings in terms of subsection (20 or (30 of sections 17, shall not be such as to impair the stability of the wall or any part of it.

(2) The distance between any part of an opening made in an external wall and the outer face of return external wall, shall not be less than one-and-a-half times the thickness of the wall in which the opening is made, unless adequate support at the corner is provided by other means.

(3) Adequate means of supporting the super structure shall be provided over every opening in any wall.

41. BEARINGS FOR BEAMS OTHER THAN TIMBER IN EMPIRICAL CONSTRUCTION.

(1) The number size or position of openings in a wall, including chases or recesses regarded as openings in terms of subsection (20 or (30 of sections 17, shall not be such as to impair the stability of the wall or any part of it.

(2) The distance between any part of an opening made in an external wall and the outer face of return external wall, shall not be less than one-and-a-half times the thickness of the wall in which the opening is made, unless adequate support at the corner is provided by other means.

(3) Adequate means of supporting the super structure shall be provided over every opening in any wall.

42. MINIMUM REQUIREMENTS FOR MATERIALS FOR EMPIRICAL CONSTRUCTION.

(1) Except where otherwise specifically permitted in this Chapter, the compressive strength of building-units and the class of mortar used in the erection of empirically constructed masonry walls which are not heavily veneered shall be not inferior to that shown in Table VI and VII for the type of wall and construction, and for the storey or total height of the wall concerned.

(2) No interpolation in strength of unit may be made for intermediate total heights of wall in Table VII.

(3) For the purposes of this section only, where a foundation-wall has a height at any point which exceeds 1,5 metres, measured from the top of the foundation-footing or other support to the underside of the ground floor, then such wall shall be regarded as being in an additional storey below the ground storey.

(4) If the height measured in terms of subsection (3) is less than 1,5 metres at all points, the foundation-wall shall be regarded as being in a separate storey, and the materials in it shall be required for walls in the ground storey.

TABLE VI
MINIMUM REQUIREMENTS FOR MATERIALS OTHER THAN SOIL-CEMENT* USED IN EMPIRICALLY CONSTRUCTED MASONRY BEARING-WALLS

1	2	3	4	5
		Brick size	block size	weakest class of mortar
storey	type of construction
single story or topmost storey	light mass	7,0	2.8	C
	not light mass	7,0	3.4	C
		10,5	–	(D) or (C)
first story before top most storey	light mass	8.4	–	B
	not light mass	–	2.8	C
second story before top most storey	light mass	10.5	3.4	C
	not light mass	10.5	4.9	B
third story before top most storey	light mass	17,5	7.0	B
	not light mass	28.0	Not-permitted	B

*In the case of soil-cement bricks and blocks, the strength thereof when tested in accordance with the standard specification for clay bricks or concrete blocks respectively, as set out in section 5, shall be at least less than 2,8 mega pascals, and class C or B mortar shall be used in a single-storey building or the topmost story, while class B mortar shall be used in a block wall in a storey of a building below the topmost storey.
+Calculated on gross area of unit
For block walls when walls are less than 200 millimetres in thickness, 4,9 megapascals (see section 57).
for block walls less than 200 millimetres thick, class B.
|| when walls are in accordance with Table X, class C or better.

(5) The compressive strength of building-unit and the class of mortar used in empirically constructed masonry walls carrying heavy veneer shall not be inferior to that shown in Table VIII.

(6) No interpolation in strength of unit may be made for intermediate total heights of wall.

(7) The mass of the veneer carried on empirically constructed masonry shall not exceed 170 kilograms per square meter, inclusive of backing mortar, and class D mortar shall not be used.

(8)Such walls may be built of the same minimum grade of materials as those set out in Tables VI and VII if their thickness is made at least 100 millimetres greater than that given in Table VIII for the maximum total height of wall and material concerned.

(9) The requirements for the materials and the dimensions of empirically constructed masonry walls carrying light veneer shall be the same as those for masonry walls without veneer.

(10) The cube strength at 28 days of concrete used in empirically constructed walls and piers shall be not less than as follows-

a) for normal concrete and light-mass normal concrete, it shall be as specified in section 14;

b) for no-fines concrete, it shall be as specified in section 14, except that, in the following cases it shall be –

i) in all walls less than 200 millimetres in thickness, 2,45 megapascals;

ii) in walls of dwelling-houses in the second storey below the topmost storey, 2,8 megapascals

(11) Where, under this section, building-units of different strengths are to be used in different storeys of a building-

a) the units of each different strength shall be clearly distinguished from those of any other strength, either by means of colour or surface texture, and shall be delivered and kept separate from them; and

b) the same combination of unit strength and mortar class shall be used throughout in the bearing-walls and piers in any one storey, and this combination shall be stated on the building plans referred to in Chapter 2; and

c) the person erecting building shall at all times keep available and ready for use not less than three nominal 100-millimetre cube-moulds as described in B.S. 1881, Methods of testing concrete.

(12) If the average strength of any three cubes of mortar cast in terms of paragraph (c) of subsection (11), when tested in accordance with the provisions of Chapter 2, is less than the minimum specified in subsection (7) of section 13 for the class of mortar which is marked on the plans for the work concerned, then the masonry in which the mortar, which is represented by those cubes, was used shall be deemed not to comply with the requirements of these by-laws.

(13) Where neither the height nor the length of an empirically constructed panel-wall exceeds 90 per centum of the maximum value permitted in section 52 or 57, as the case may be, mortar not weaker than class C may be used in such walls, and where neither of such dimensions exceeds 75 per centum of such values, class D mortar may be used.

TABLE VII
MINIMUM REQUIREMENTS FOR MATERIALS USED IN EMPIRICALLY CONSTRUCTED NON -BEARING WALLS

1	2	3	4	5
		Minimum compressive strength of units megapascals for
		Brick size	block size	weakest class of mortar
Maximum total height of wall metres	type of construction
A. Curtain -Walls
7.2	All kinds	7,0	2.8	D
12.3	light mass	7,0	2.8	D
	not light mass	10.5	3.4	C
18.3	All kinds	21.0	7.0	C
B. PARTITION WALLS	ALL KINDS	7.0	2.8	D
C.PARTITION WALLS	ALL KINDS	10.5	2.8	B
D. FREE STANDING WALLS	NOT LIGHT MASS	10.5	3.4	B
E.RETAINING WALLS	NOT LIGHT MASS	14.0	7.0	A

43. DIMENSIONS OF EMPIRICALLY CONSTRUCTED WALLS CARRYING HEAVY VENEER.

(1) Empirically constructed masonry walls leaves of cavity-walls, carrying heavy veneer should comply with the requirements set out in subsections to (6) and in Table IX for the types of walls mention
in that Table.
(2) In no case shall the thickness be less than least value given for the relevant type of wall and storey-height, and for blocks not less than 2 millimeter’s.
(3) The storey-height shall not exceed the va given for the relevant type of wall and the minim thickness.
(4) Panel-walls shall be fixed along their tops specified in section 31.1
(5) Partition-walls shall be similarly fixed al their tops or be fixed by wedging under the struct member above with hard, durable materials. filling in solid around the wedges with mortar.
(6) The total height shall not exceed the ma mum figure shown for the relevant type of w regardless of its thickness.

MINIMUM REQUIREMENTS FOR MATERIALS USED IN EMPIRICALLY CONSTRUCTED MANSORY WALLS CARRYING HEAVY VENEER.

1	2		3	4	5
				Minimum compressive strength of units megapascals for
Maximum total height measured from top of wall metres	Minimum permissible thickness of of wall in lowest storey millimetres	Type of construction	Brick size	Block size	Class of mortar for units spared
A. BEARING -WALLS
7.2	215	All kinds	14,0	10.5	B
10.8	330	All kinds	28,0	14.0	B
B. PARTITION WALLS	ALL KINDS		7.0
		LIGHT MASS	7.0	4,9	B
7,2	215	NOT LIGHT MASS	10.5	7.0	B
10,8	215	LIGHT MASS	10.5	7.0	B
		NOT LIGHT MASS	21,0	14,0	B
C.PARTITION WALLS	AND PANEL WALLS	FIXED AT TOP
2,7	100	SOLID	7,0
2,7	100	CAVITY	7,0	BLOCKS NOT PERMITTED	C
3,6	100	CAVITY	21,0
3,6	215	SOLID	10,5	4,9	C

LIMITING DIMENSIONS OF EMPIRICALLY CONSTRUCTED WALLS CARRYING HEACY VENNER.

1		2	3	4
Type of wall		Minimum thickness millimetres	Maximum storey height metres	Maximum total height height of wall meters
Bearing walls and curtain walls		215	3,6	10,8
	solid	100	2,7	2,7
	cavity	100	3,6	3,6
	solid	215	3,6	3,6

44.PERMISSIBLE “STOREY” DIMENSIONS FOR EMPIRCALLY CONSTRUCTED BRICK BEARING-WALLS.

(1) For empirically constructed brick bearing- walls, the storey-height and unsupported length of wall in any storey shall fall within the limits specified in Table X or XI for the class of mortar used, effective thickness of wall and the storey concerned.
(2) The actual thickness of walls shall be not less than the minimum effective thickness shown for the storey concerned.

45. EMPIRICALLY CONSTRUCTED BRICK FOUNDATION-WALLS AND BASEMENT WALLS.

(1) Empirically constructed brick foundation-walls, sleeper-walls

(1) For empirically constructed solid-brick bearing walls, the total height of the wall, including the height of the foundation-wall, shall not exceed the following, when laid in class A, B or C mortar-

a) for single-storey buildings, 5,4 metres;

b) for two-storey building, 9 metres;

c) for three-storey buildings, 12 metres;

d) for four-storey buildings, 15 metres.

(2) When such walls are laid in class D mortar, such maximum height shall not exceed 5,4 meters.

(3) In buildings which have more than four storeys, or walls higher than 15 meters, the walls shall be designed in accordance with requirements of section 63 to 82.

TABLE X
PERMISSIBLE DIMENSIONS FOR EMPIRICALLY CONSTRUCTED BRICK BEARING-WALLS LAID IN CLASS D MORTAR*

1	2	3	4	5	6
		Maximum storey height height for
		External Walls
Minimum effective thickness millimetres	Maximum unsupported length metres	Moderately restrained at the top of the storey	Fully restrained at the top of the storey	Moderately restrained at the top of the storey	Fully restrained at the top of the storey
215	6,6	not permitted	2,7	3,0	3,6
215	5,4	3,0	3,6	3,3	4,2
330	7,2	4,2	5,4	4,5	5,4

*Class D mortar may be used in bearing-walls only in buildings or the topmost storey of a building.
†See definition of “restrained”, “a fully restrained at the top” and “a wall moderately restrained at the top”.
Joisted timber floors and precast concrete floors not anchored in accordance with section 25 shall be regarded as giving no lateral restraint to the walls supporting them.

46. EMPIRICALLY CONSTRUCTED BRICK FOUNDATION-WALLS AND BASEMENT WALLS.

(1) Empirically constructed brick foundation-walls, sleeper-walls or basement-walls shall coply with the requirements of the following subsections.

(2) The effective of such walls shall be not less than 215 millimetres, measured exclusive of skin-walls which protect damp-proof treatment.

(3) Fill placed between such walls shall not be placed before the periods set out in section 9 have elapsed after completion of such walls, and such fill shall, in opinion of the local authority, be sufficiently dry at the time of placing, and sufficiently well drained.

(4) The full height of the fill referred to in subsection(3), measured above the adjoining finished ground-level, shall not exceed the following-

a) for a wall 215 millimetres in thickness, 1,8 metres;

b) for a wall 280 millimetres in thickness, solid, 2,1 metres;

c) for a wall 330 millimetres in thickness, 2,7 metres:

Provided that the height of such fill shall not exceed one metre where the fill shall not exceed one metre except where the fill is one of hardcore or the floor is designed and constructed as a suspended floor and carried through the thickness of the supporting walls.

(5) The full height of exterioe back-filling, measured above the level of a solid floor or above the ground surface under a suspended floor, placed against such wall shall not exceed the values given in subsection (4) for fill, and the following requirements shall be complied with-

a) there shall be no surcharge above the point at which the surface of the back-filling meets such wall;

b) the back-filling shall be drained to the satisfaction of the local authority;

c) the thickness of any skin-wall which protects vertical damp-proof or waterproof layers shall not be included in the thickness of any foundation-wall or basement-wall when the permissible height of back-filling id determined.

47. EMPIRICALLY CONSTRUCTED BRICK BEARING-WALLS 100 MILLIMETRES IN THICKNESS.

(1) Empirically constructed brick bearing-walls shall have a thickness of not less than 100 millimetres, and shall be constructed to comply with the requirements of the following subsections.

(2) external walls of a thickness of 100 millimetres shall be permitted to be constructed for use in any veranda, loggia, garage to a dwelling-house, greenhouse, servant’s quarters to a dwelling-house, tool-shed, potting shed, cycle-shed, aviary, poultry-house or summer-house, or a dwelling-house in an area designated by the local authority:

Provided that-

a) every such wall shall not exceed 2,5 metres in total height;

b) in the case of multi-storey buildings, the length of every such wall shall not exceed 3,4 metres by a pier or piers, 215 millimetres square in total horizontal cross-section, bonded into it, in which case the total length of every such wall may be 10,63 metres;

c) in the case of single-storey buildings, the length of every such wall shall not exceed 4 metres, unless it is divided into panels of no greater length than 4 metres by a pier or piers, 215 millimetres square in total horizontal cross-section bonded into it, in which case the total length of every such wall may be 8 metres;

d) except in the case of a veranda or loggia-

i) the building shall be wholly detached from any other building; and

ii) the building shall be approved designed; and

1	2	3	4	5	6	7	8
				Maximum storey height height for
			External walls which at the top of the storey are				Internal walls which at the top of the storey are
Storey	Effective thickness millimeters not less than	Maximum unsupported length meters	Moderately restrained	Fully restrained	Un- restrained	Fully restrained	Moderately restrained
A.SOLID WALLS
	100	5,4 6,0	only in accordance with section 47		not permitted	2,7 3,3	3,0 3,6
	215	9,0 6,0	3,3 4,2	4,2 4,8	3,0	4,8	5,4
single storey or top most storey	330	12,3 9,0 6,0	4,2 4,8 15,3	5,4 5,4	4,2	5,4	5,4
	440	15,3	5,4	5,4	4,5	5,4	5,4
First story below top most storey	100	5,4 6,0	not permitted	not permitted	not permitted	not permitted	3,0 3,6
	215	9,0 6,0	3,3 4,2	4,2 4,8	not permitted	4,8	5,4
	330	9,0	5,4	5,4	3,6	5,4	5,4
Second story below top most storey	215	9,0	not permitted	notpermitted	not permitted	4,8	5,4
	330	9,0	4,5	5,4	3,6	5,4	5,4
	440	9,0	5,4	5,4	4,8	5,4	5,4
Third story below top most storey	330 440	9,0 9,0	not permitted 5,4	not permitted 5,4	3,0 4,2	5,4 5,4	5,4 5,4
B. Cavity Walls
Single storey only	180(65-50 cavity -65) wall bonded by header bricks 215(65-50 cavity -100) or 195(65-65 cavity -65) wall bonded by header bricks	3,6 3,6	2,7 3,0	2,7 3,0	not permitted	2,7 3,0	2,7 3,0
Topmost storey and first storey below top most storey	280 (actual thickness ) (100-75 cavity -100)	9,0 6,0 4,2	3,0 3,3 3,6	3,3 3,6 4,2	2,7 2,7 3,0	3,3 3,6 4,2	3,6 4,2 4,8

iii) the volume of the building shall not exceed 60 cubic metres except a dwelling-house in an area designated by the local authority;

e) the roof resting on such walls be so constructed that no load other than the mass of the roof and the wind force on it shall be transmitted by the roof to the wall;

f) the highest point of the roof resting on such walls shall be not more than 1,5 metres above the top of any of them;

g) except in the case of the walls constructed of brick of a compressive strength of not less than 15 megapascals and water absorption not exceeding 12 per centum laid in class B mortar, as defined in subsection (3) of section 13, every such wall of every habitable room shall be plastered externally with plaster complying with the requirements of class D mortar in section 13 to a thickness of class D mortar in section 13 to a thickness of not less than 10 millimetres.

(3) External walls of 100 millimetres in thickness shall be permitted to be constructed for use in a structure above the general level of a flat roof of a building and need not be subject to the limitations set out i subsection (2) if-

a) such structure is not used or adapted to be used as a habitable room or as workroom or office; and

b) the height of the walls does not exceed 2,4 metres, measured to the it top from the level of the flat roof adjacent; and

c) the length of the walls does not exceed 3 metres.

(4) Internal walls of 100 millimetres effective thickness shall be constructed in accordance with table XI, and shall-

a) be of brick with a compressive strength of not less than 7 megapascals or such other strength as the local authority shall determine; and

b) be laid in class B mortar; and

c) not be used in storeys other than the topmost two storeys of a building; and

d) in a single-storey building or the topmost storey of a building, be at least moderately restrained at the top.

48. EMPIRICALLY CONTRUCTED BRICK WALLS ABOVE THE ROOF.

(1) Empirically constructed external brick bearing-walls, when used to enclose stairways or habitable or working-space above the general roof-level shall be not less than 215 millimeters in thickness.

(2) If the walls referred to in subsection (1) are not hight than 3,6 metres, and the area enclosed between them does not exceed 10 per centum of the area of the roof, they may be constructed as though they did not add to the number of storeys of the building:

Provided that the local authority may, in its discretion, require the thickness of the walls in the storeys immediately under such first-mentioned walls, or under structural members supporting them, to be determined as though the walls above the general roof-level constituted an additional storey.

49 EMPIRICALLY CONSTRUCTED BRICK CAVITY-WALLS.

(1) Empirically constructed brick cavity bearing-walls shall comply with the requirements of this section.

(2) In single-storey dwelling-houses only, such walls shall have less than 65 millimetres in thickness, and their dimensions shall comply with Table XI.

(3) Such gable-walls with leaves 65 millimetres in thickness shall have a height to the top of the gable not exceeding the following-

a) for a wall bonded with header bricks at every alternate course, 4,8 metres;

b) for a wall bonded otherwise than as described in paragraph(a), 3,6 metres.

(4) If such cavity-walls with leaves 65 millimetres in thickness are bonded into pier or piers of a total solid cross-sectional area not less than 440 by 330 millimetres, not farther apart than 3,6 metres by shall not exceed 7,2 metres

(5) In all two-storey buildings, the leaves of such walls shall not be less than 100 millimetres in thickness, and shall comply with the dimensions set forth in Table XI.

(6) Such walls having leaves 100 millimetres in thickness shall not exceed two storeys in height, and the height to the top of the gable of any such gable-wall, measures from the floor of the gabled storey, shall not exceed 4,8 metres.

50.EMPIRICALLY CONSTRUCTED BRICK COLUMNS .

(1) Columns which are sleep-piers may be built without design if they are not less than 215 by 215 millimetres in cross-section and not higher than eight times their lateral dimension, and are bedded on a foundation complying with the provisions of Chapter 4.

(2) All other columns shall be designed in accordance with sections 63 to 82, unless otherwise permitted by the local authority.

51. EMPIRICALLY CONSTRUCTED BRICK WING-WALLS.

(1) Empirically constructed brick wing-walls shall be at least moderately restrained along their tops and shall be not less than 100 millimetres in thickness, and shall not continue though more than two storeys.

(2) The storey-height and the length of such wall shall not exceed the following –Table.

Minimum thickness millimeters.	Maximum storey height	Maximum length
100	2,7	1,8
215	3,6	3,6

52. EMPIRICALLY CONSTRUCTED BRICK CURTAIN-WALLS AND PANEL-WALLS

(1) Empirically constructed brick curtain-walls shall-

a)have a thickness which is –

i) not less than 215 millimetres; and

ii) uniform throughout the height of the wall in any one storey; and

b)nor exceed a height of-

i) 5,4 metres in any one storey; or

ii) a total of 18, 3 metres when laid in class A, B or C mortar; or

iii) a total of 7,2 metres when laid in class D mortar

(2) Empirically constructed solid brick or cavity brick panel-walls have an effective thickness of not less than 100 millimetres.

(3) The effective thickness of faced panel-walls shall include brickwork and facing, but that of veneered panel-walls shall exclude the veneer.

(4) walls constructed as panel-walls shall sustain no forces other than their own mass and wind forces unless such other forces are approved by the local authority.

(5) Panel-walls which contain openings shall be fixed along their tops in the manner specified in section 31, and the curves designated in Figure 1 as “top fixed” refer to panel-walls so fixed.

(6) The length and height of any panel-wall shall not exceed the values corresponding to any point on the appropriate curve in Figure 1 for the relevant condition of the top of the panel-wall and its thickness.

53. Empirically Constructed Brick Parapet-Walls And Balustrade-Walls

(1) Empirically constructed brick parapet-walls shall have a thickness of not less than one sixth of their height or 215 millimeters, whichever is the greater, and shall be laid in class A mortar.

Figure 1

(2) They shall be reinforced in the highest four bed-joints with reinforcement consisting of two stands of steel wire of a diameter or not less than 3,55 millimetres, or two steel strips of equivalent cross-sectional area per bed-joint, and such reinforcement shall be lapped over a distance of at least 150 millimetres with the anchors to the supporting-columns required by section 27.

(3) Empirically constructed brick balustrade-walls shall be not less than 100 millimetres in thickness, and shall be laid in class A mortar and reinforced as required by subsection (2).

54. Dimensions Of Empirically Constructed Brick Partition-Walls.

The maximum height of empirically constructed brick partition-walls shall be set out in Table XII for the thickness, and unsupported length also set out in that Table.

TABLE XII

1	2	3
thickness millimeters	maximum height meters	maximum unsupported length meters
65 100 150 200 215	3,0 3,3 4,2 4,8 6,0	4,5 9,0 9,0 9,0 9,0

*Thinner partition-walls may be constructed, subject to the approval of the local authority.

55. Dimensions Of Empirically Constructed Brick Free-Standing Walls

(1) Free-standing brick walls of the minimum thickness shown in Table XIII shall not be constructed empirically to greater heights above the adjoining finished ground level than are set forth in that Table.

(2) Where the details of piers are given in Table XIII, every such wall shall be bonded into piers which, together with the thickness of such wall, shall comply with the minimum dimensions set forth in that Table and are spaced in accordance with the maximum dimensions laid in that Table.

(3) The foundation of every such wall shall project not less than 120 millimetres from the face of each side of such wall, and the piers, if any, in such wall shall not overhang such foundation.

(4) The upper surface of such foundation shall be not less than 150 millimetres below the adjoining finished ground-level at any point.

Table XIII
EMPIRICALLY CONSTRUCTED BRICK FREE-STANDING WALLS

1	2	3	3	4
Minimum thickness millimeters	Minimum dimensions including thickness of wall in millimeters	Maximum spacing center to center in meters	Maximum height above finished ground. level in meters	Minimum dimensions including width x depth in millimeters
100 100 215 215 330	– 230 x 115 – 330 x 215 –	– 2,4 – 4,0 –	1,0 1,4 1,7 2,1 3,0	450 x 200 450 x 250 550 x 250 630 x 250 800 x250

*The largest dimension to be constructed at right-angles to the wall.
(5) Such foundation shall be of concrete which shall comply with the relevant requirements of section 14.
(6) No damp-Proof course shall be permitted between such wall and its foundation.

56. Dimensions Of Empirically Constructed Brick Retaining-Walls.

(1) Empirically constructed brick non-bearing retaining walls shall conform to the dimensions and be subject to the conditions prescribed in subsections (2) to (9).

(2) No superimposed loads, except pedestrian traffic shall be permitted behind the retaining wall within a distance equal to the height of the wall.

(3) No structure shall be erected on such wall except framed or wired fences no covered with sheeting and not exceeding 1,4 metres in height.

(4) The upper surface of the fill behind such a wall shall be approximately level.

(5) Expansion joints shall be provided in such retaining-walls at distances apart not exceeding 24 metres , and where piers are provided, expansion joints shall bisect piers.

(6) Every such retaining wall shall ne constructed vertical, shall be bonded into or cast integrally with piers which shall be built on the side of such wall remote from the fill and to the full height of such wall:

Provided that, where no details of piers are given in Table XIV, no piers are required.

(7) Every such pier shall have the minimum cross-sectional area set forth in Table XIV.

(8) Every such retaining-wall and its piers, if any, shall be built on a foundation of the minimum dimensions set forth in Table XIV, which foundation shall be constructed of concrete complying with the requirements of section 14.

TABLE XIV
DIMENSIONAL REQUIREMENTS OF EMPIRICALLY CONSTRUCTED NON-BEARING BRICK RETAINING WALLS AND THEIR PIERS AND FOUNDATIONS

1	2	3	4	5
Maximum height of wall and piers above finished ground. level in meters	Minimum thickness of wall millimeters	Minimum cross -sectional area of piers projection x length in millimeters	Maximum spacing of piers center to center meters	Minimum dimensions of foundations including width x depth in millimeters
0,9 1,2 1,5 1,5 1,7 2,0	215 215 215 330 330 330	– 100 x 330 215 x 440 – 100 x 330 215 x 440	– 2,4 3,0 – 3,0 3,0	750 x 250 600 x250 700 x250 900 x 250 700 x250 850 x250

(9) the upper surface of such foundation shall be at least 150 millimetres below the adjoining finished ground-level, and neither the retaining-wall nor any associated pier thereof shall overhang such foundation.

(10) Empirically constructed brick retaining-walls which are bearing walls shall comply, mutatis mutandis, with the requirements of section 46.

57. Requirements for Empirically Constructed Masonry of Blocks.

(1) Thickness.- Empirically constructed natural stone walls shall comply with the following requirements for thickness-

a) the thickness of ashlar stone walls shall be not less than that specified under the same conditions for solid brick walls in sections 44 to 56;

b) the thickness of squared rubble walls shall be not less than that specified under the same conditions for solid brick walls in sections 44 to 56, and in no case less than 230 millimetres for bearing-walls or less than 150 millimetres for non-bearing walls.

c) The thickness of random rubble walls shall be 150 millimetres greater than that specified under the same conditions for solid rock walls in sections 44 to 56, and in no case less than 330 millimetres for bearing-walls or less than 230 millimetres for non-bearing walls.

(2) Height and length of empirically constructed natural stone walls.- The height and length of any empirically constructed wall of natural stone shall be as prescribed by sections 44 to 56 for a solid brick wall of the same thickness:

Provided that, in the case of a random rubble wall, the height and length shall be as prescribed for a solid brick wall having a thickness 150 millimetres less than the thickness of the random rubble wall.

(3) Natural stone retaining walls.- Every empirically constructed natural stone retaining wall shall comply with the following requirements-

a) it shall comply with provisions of subsections (2) to (5) of section 56 for brick retaining walls:

Provided that a batter may be used on the outside face of the wall if it does not exceed 1 in 10;

b) its thickness at the top shall be not less that 230 millimetres, and, at any point below the top, its thickness shall be not less than 40 per centum of the height of wall above that point;

c) it shall be constructed on a concrete foundation at least 250 millimetres in thickness, projecting at least 150 millimetres beyond the edge of the base of the wall at either side, and constructed of concrete complying with the requirements of section 14;

d) its height shall not exceed 2 metres;

e) the mortar used in such wall shall be class A mortar.

58. Requirements For Empirically Constructed Masonry Of Natural Stone

(1) Thickness.- Empirically constructed natural stone walls shall comply with the following requirements for thickness-

a) the thickness of ashlar stone walls shall be not less than that specified under the same conditions for solid brick walls in sections 44 to 56;

b) the thickness of squared rubble walls shall be not less than that specified under the same conditions for solid brick walls in sections 44 to 56, and in no case less than 230 millimetres for bearing-walls or less than 150 millimetres for non-bearing walls.

c) The thickness of random rubble walls shall be 150 millimetres greater than that specified under the same conditions for solid rock walls in sections 44 to 56, and in no case less than 330 millimetres for bearing-walls or less than 230 millimetres for non-bearing walls.

(2) Height and length of empirically constructed natural stone walls.- The height and length of any empirically constructed wall of natural stone shall be as prescribed by sections 44 to 56 for a solid brick wall of the same thickness:

Provided that, in the case of a random rubble wall, the height and length shall be as prescribed for a solid brick wall having a thickness 150 millimetres less than the thickness of the random rubble wall.

(3) Natural stone retaining walls.- Every empirically constructed natural stone retaining wall shall comply with the following requirements-

a) it shall comply with provisions of subsections (2) to (5) of section 56 for brick retaining walls:

Provided that a batter may be used on the outside face of the wall if it does not exceed 1 in 10;

b) its thickness at the top shall be not less that 230 millimetres, and, at any point below the top, its thickness shall be not less than 40 per centum of the height of wall above that point;

c) it shall be constructed on a concrete foundation at least 250 millimetres in thickness, projecting at least 150 millimetres beyond the edge of the base of the wall at either side, and constructed of concrete complying with the requirements of section 14;

d) its height shall not exceed 2 metres;

e) the mortar used in such wall shall be class A mortar.

59. Requirements For Empirically Constructed Masonry Of Soil-Cement Building Units.

Every empirically constructed wall of pre-cast soil-cement building -units shall comply with the following requirements-

a) a bearing-wall shall have a thickness of not less than 200 millimetres for a solid wall or not less than 150 millimetres for each leaf of a cavity-wall, and every partition-wall have a thickness of not less than 100 millimetres;

b) the storey-height of a bearing-wall shall not exceed 12 times its effective thickness, and its length shall not exceed 30 times its effective thickness;

c) wall-sections less than 600 millimetres in length between openings shall be regarded as providing no support to the wall above the openings, and such wall shall, according , be supported by a lintel spanning over both openings; and

d) every non-bearing wall shall comply with the requirements for a similar non bearing brick-wall, and shall have a minimum thickness of 100 millimetres and be subject to the provisions of section 35.

60. Requirements For Empirically Constructed Masonry Of Gypsum Blocks.

(1) Only non-bearing interior walls which are not likely to be exposed to continual dampness may be constructed of gypsum blocks.

(2) The dimensions of walls of gypsum blocks shall comply with the requirements for brick partition-walls set out in section 54.

61. Empirically Constructed Plain Normal Concrete Walls And Columns.

(1) Every empirically constructed bearing-wall, pier and column of plain normal concrete shall comply with the requirements of this section.

TABLE XV

(2) The effective thickness of such wall shall be not less than set out in Table XV for the same conditions as those set out in sections 44 to 56 for brick wall of the corresponding effective thickness.

TABLE XV
MINIMUM EFFECTIVE THICKNESS OF EMPIRICALLY CONSTRUCTED PLAIN NORMAL CONCRETE BEARING WALLS

1	2
Corresponding effective thickness of solid brick wall millimeters	Minimum effective thickness of solid brick wall millimeters
100 140 215 330 or greater	100 125 200 330 or greater

(3) The provisions of subsection (2) shall also apply to the effective thickness of stiffened walls determined in accordance with the provisions of subsections (5) to (10) of section 66.

(4) Reinforcement shall be placed around all openings, and reinforcing bars shall be distant not less than 25 millimetres above and not less than 50 millimetres below, and not less than 40 millimetres horizontally from every edge of every opening, and shall extend for a distance of not less than 48 times the bar diameter beyond the edges of the opening:

Provided that such distance may be reduced by the provision of hooks as specified in Chapter 3.

(5) Instead of providing reinforcement as required in subsection(4), a reinforcing bar may be replaced to extend diagonally past each corner of the opening, so as to pass not less than 50 millimetres from such corners and to extend not less than 600 millimetres in both directions from the point nearest to the corner of the opening.

(6) The mass of such reinforcement around openings shall be equivalent to that of one 10 millimetres bar for each 100 millimetres, or remaining portion thereof, thickness of the wall, and it shall be symmetrically disposed in the thickness of the wall.

(7) Plain, normal concrete piers cast integrally with such wall to its full height may be assumed to increase effective thickness as set out in subsections (6) and (9) of section 66 if such piers comply with the requirements of those subsections.

(8) Plain concrete columns shall be designed in accordance with the requirements of sections 63 to 82.

62. Empirical Construction In No-Fines Concrete.

(1) Every empirically constructed no-fines concrete bearing-wall shall comply with the requirements of the following subsections.

(2) Its thickness shall be as set out in Table XVI, except that, where it employs, light-mass aggregate and supports a flat, heavy roof, it shall be at least 50 millimetres greater in thickness than set out in Table XVI .

TABLE XVI
MINIMUM THICKNESS OF EMPIRICALLY CONSTRUCTED NO-FINES CONCRETE BEARING-WALLS

1	2		3	4	5
Storey		Minimum thickness of walls millimeters for
	Dwelling houses		Other buildings
	External	Internal	External	Internal
Topmost Storey or single Storey	200	100	200	200
first below topmost Storey	200	150	300	200
Second below topmost Storey	300	200	Not	Permitted

(3) Such wall shall not be used in a storey other than those described in Table XVI.

(4) Where such wall is 200 millimetres or more in thickness, it shall have a storey height not exceeding 3,6 metres, and, where it is less than 200 millimetres in thickness, it shall have a storey height not exceeding 2,7 metres.

(5) Sections of wall between openings shall be not less in width than 450 millimetres, unless bridged over by a lintel as required by sections 17 and 18.

(6) Reinforcement shall be provided around openings as prescribed for walls of normal concrete, except that horizontal reinforcement shall be provided over each opening, as follows-

a) for a clear span exceeding 1,5 metres , a lintel of normal reinforced concrete, designed as such;

b) for a clear span of 1,5 metres or less, a lintel of reinforced no-fines or normal concrete:

Provided that a no-fines concrete lintel shall be not less than 300 millimeters in depth, and shall be reinforced with two 12 millimetre diameter steel bar or reinforcement of equivalent cross-sectional area.

63. Application of Certain Sections.

The provisions of sections 64 to 82 shall apply in the calculated design of masonry construction.

64. General Requirements For Design.

(1) Walls, piers and columns shall be so proportioned that the stresses in them due to the worst combination of forces to which they may be subjected 13 do not at any point exceed the values presented in sections 67 to 73 and section 78 for the several materials and conditions to which those sections relate.

(2) Provision shall be made for the transfer of all lateral forces to the ground without causing stresses in excess of those referred to in subsection (1).

65. Dispersion And Application Of Forces.

(1) In considering the transmission of forces through walls and other structural members of masonry and cast-in-situ concrete, the angle of dispersion of the forces through the material shall be taken as being not greater than 45 degrees from the direction of the forces.

(2) Roof-loads from trussed roofs or girder roofs shall be considered as being applied along a line passing through the centre of the bearing-area.

(3) Roof-loads from flat-slab roofs and floor-loads other than those from cantilevers shall be considered as being applied along a line which is related to the width of the bearing-areas as follows-

a) for slabs of normal concrete employing ordinary aggregate and bearing on the full thickness of the wall, and either extending on both sides of the supporting-wall or extending on one side only of such wall but having an effective span not exceeding 24 times the thickness of such slab, such line shall be assumed to be axial;

b) for timber floors and for slabs of concrete other than those described in paragraph (a) extending on both sides of the supporting-wall where the span on the one side of the wall does not exceed that on the one side by more than 50 per centum, such line shall be assumed to be axial.

c) For all roofs and floors, other than those described in paragraph (a) or (b), such line shall be assumed to be displaced from the centre of the bearing-area towards the span of the roof or floor(where there is only one span) or towards the larger span (where there are two unequal spans), and such eccentricity shall be deemed to be one-sixth of the width of the bearing of the roof or floor, whether or not this width of bearing is equal to the full thickness iof the supporting-wall.

66. Slenderness Ratio.

(1) Value of slenderness ratio.- The slenderness ratio of a wall shall be taken as the ration of the effective height to the effective thickness, or that of the effective length to the actual thickness, whichever ratio is smaller:

Provided that the slenderness ratio of a free-standing wall shall be taken as the ratio of the effective height to the effective thickness.

(2) The slenderness ration of a column shall be taken as the ratio of the effective height in the direction under consideration to the lateral dimension of the column in the same direction, or to the diameter, were the column is circular.

(3) Effective length.- The effective length of a wall shall be taken as two comma five times the unsupported length for a wing-wall, and as the unsupported length for any other type of wall14.

(4)Effective height.- The effective height of walls and columns for the conditions of lateral restraint indicated in the Table shall be set out in Table XVII , where H is taken as-

a) for a bearing-wall or curtain-wall, the height of the storey;

b) for a panel-wall or a partition-wall or a partition-wall or a column, the actual height from the top of the floor construction, collar-beam or frame-work above;

c) for a free-standing wall or a wing-wall, the actual height.

(5) Effective thickness.- The effective thickness of a solid wall, without piers, shall be the actual thickness of such wall.

(6) The effective thickness of a solid wall stiffened by piers bonded shall be obtained by multiplying the actual thickness of such wall by the factor given for the dimensions and spacing of the piers in Table XVII if the width of the pier parallel to the length of the wall is not less than twice the actual thickness of the wall, tw, and the total thickness of the pier (including the thickness of the wall), tp , is not less than 2tw:

Provided that bonded intersecting-walls of a thickness not less than tw may be regarded as piers of effective pier-thickness tp14 equal to half the unbroken length of the intersecting-wall plus the thickness of the stiffened wall.

TABLE XVII
EFFECTIVE HEIGHT OF WALLS AND COLUMNS

1	2	3
Member	Condition of restraint at top	Effective Height
walls	fully restrained……………………………………… Moderately Restrained……………………….. unrestrained ………………………………………	0.75H 1.0H 1.5H
columns	fully restrained…………………………………….. unrestrained ………………………………………..	1.0H 2.0H

TABLE XVIII
FACTORS FOR EFFECTIVE THICKNESS OF STIFFENED MASONRY AND CONCRETE WALLS
(Effective thickness= actual thickness x factor)

1	2	3	4	5	6
	6 or less	8	10	15	20 or more
	1,4	1,3	1,2	1,1	1,0
	2,0	1,7	1,4	1,2	1,0

13 The minimum forces for which provision must in all cases be made are set out in Chapter 3.
14 See definition of “length of wall”.

(7)When the thickness of a wall is changed between the bottom and the top of a storey or of a wall, its effective thickness shall be calculated by multiplying the thickness of each section of constant thickness by its heights and dividing the sum of their products by the total height of the wall.

(8) The effective thickness of an unstiffened cavity-wall shall be found from the expression
te = 2/3 (to – w), where-

te = effective thickness; and
to = overall thickness; and
w = width of cavity.

(9) The effective of a cavity-wall stiffened by piers shall be taken as the effective thickness of the unstiffened wall multiplied by the factors specified in Table XVIII for the size and spacing of piers concerned:

Provided that-

i) the over-all thickness of the wall, to, shall be used in place of tw in determining the minimum size and spacing of piers; and

ii) piers are bonded to one leaf of the wall.

(10) Where, in a cavity-wall, one leaf is designed to carry total superimposed load, the permissible stress for that leaf shall-

a) be based on the slenderness ration calculated from the effective thickness of the whole wall; or

b) be take as the actual thickness of the load-bearing leaf;

whichever gives the smaller value of the slenderness ratio.

(11) Permissible limits of the slenderness ratio.- The slenderness ratio of walls and columns shall not exceed the value given for the relevant conditions in Table XIX .

TABLE XIX
PERMISSIBLE LIMITS OF SLENDERNESS RATIO

1	2	3	4
		Maximum value of slenderness
Class of Mortar	type of member	Bearing- walls	Non-bearing walls
A,B or C	-Unreinforced masonry walls of solid units in dwelling-houses of not more than two storeys. -Plain concrete walls -Reinforced masonry walls and columns; plain concrete columns in dwelling-houses. -All other types except reinforced concrete walls and columns	24 24 24 18	40 40 40 40
D	All types	15	24

67.Basic Stresses For Brick Masonry.

(1) For solid masonry building-units of the dimensions of bricks, the stresses in masonry due to axial vertical loads calculated as evenly distributed stresses over-

a) the cross-sectional area of a wall; or

b) if there are openings in a wall, the reduced cross-sectional area between openings; or

c) the cross-sectional area of a column;

shall not exceed the stresses set out in Table XX for the compressibe strength of such units and class of mortar set out in that Table:

Provided that-

i) the slenderness ratio does not exceed 12; and

ii) the compressive strength of such masonry building-units is determined in the manner described in section 5 for the building-units concerned.

TABLE XX
BASIC STRESSES FOR MASONRY WALLS AND COLUMNS

1	2	3	4	5
Compressive strength of building units in mega pascals
	Class A mortar	Class A mortar	Class A mortar	Class A mortar
70 49 35 28 21 17,5 14 10,5 7 4,9 3,5 2,8 2,1 1,4	2,75 2,11 1,62 1,388 1,10 0,97 0,81 0,67 0,48 0,37 0,28 0,23 0,18 0,12	1,86 1,50 1,22 1,05 0,90 0,81 0,69 0,58 0,43 0,33 0,25 0,21 0,16 0,11	1,72 1,37 1,10 0,94 0,77 0,68 0,58 0,48 0,36 0,28 0,21 0,18 0,14 0,10	0,72 0,63 0,55 0,51 0,46 0,43 0,40 0,36 0,29 0,23 0,19 0,16 0,12 0,09

(2) The permissible stresses set out in Table XX shall be designated the basic stresses for masonry.

(3) Basic stresses for intermediate strengths of the building-units aforesaid may be obtained by liner interpolation between the stresses set out in any one column of that Table.

68. Stresses for Large Slenderness Ratios.

(1) When all other conditions are as stated in section 67, with the exception that the slenderness ratio exceed 12, but does not exceed the values set out in Table XIX, then the stresses in masonry shall not exceed the basic stresses set out in section 67 multiplied by the factors set out in Table XXI.

TABLE XXI Stress Factor for Slender masonry walls and Columns.

1	2
For Slenderness ratio not exceeding	Factor
12 14 16 18 21 24 27 30 35 40	1,0 0,93 0,87 0,82 0,76 0,70 0,64 0,59 0,51 0,44

(2) The factors corresponding to intermediate slenderness ratios shall be found by linear interpolation.

69. Axial Stresses In Block Masonry .

(1) The axial stresses in masonry constructed of blocks may be increased to not more than one and a half times the values set out for brick masonry in sections 67 and 68 for the conditions described therein.

(2)The stresses in masonry constructed of cellular or hollow blocks shall not exceed those for solid blocks , and the compressive strength of cellular or hollow blocks, and the stresses on them, shall be computed on their gross cross-sectional area.

(3)The stresses in masonry built of units which have dimensions different from those prescribed for bricks or blocks shall not exceed the following values, based on the height of the units as laid in the wall-

70. Axial Stresses In Cast-In-Situ Concrete.

(1)Where the slenderness ratio does not exceed 15, the stresses due to axial vertical loads in-

a) cat-in-situ plain concrete walls computed as evenly distributed over-

i) the cross-sectional area of the wall; or

ii) if there are openings in the wall, over the reduced cross sectional area between openings; and

b) plain concrete columns;

shall not exceed those set out in Table XXII for the appropriate type of concrete.

TABLE XXII STRESSES PERMITTED IN CONCRETE WALLS AND COLUMNS

1	2	3
	Required minimum compressive strength at 28 days	Maximum permitted stress
Type of concrete		Megapascals
Normal employing ordinary aggregate	7,0	1,38 or o,1667 ever is greater
Normal employing light-mass aggregate	3,5
No-fines employing ordinary aggregate	2,45
No-fines employing light-mass aggregate	1,75

(2) Where the slenderness ration of any wall referred to in subsection (1) exceeds 15, but does not exceed the values set out in Table XIX, the stress in such wall shall not exceed the figure obtained by multiplying the stress specified in subsection (1) by the appropriate factor set out in Table XXIII

exceed the values set out in Table XIX, the stress in such wall shall not exceed the figure obtained by multiplying the stress specified in subsection (1) by the appropriate factor set out in Table XXIII.

TABLE XXIII
STRESS FACTORS FOR SLENDER CONCRETE WALLS.

1	2	3	4	5	6	7	8	9
For slenderness ratio not exceeding	15	18	21	24	27	30	35	40
Factor	1,0	0,9	0,8	0,7	0,64	0,59	0,51	0,44

71. Axial Stresses In Natural Stone Masonry

The stresses in masonry constructed of natural stone due to axial loads shall not exceed those set out in Table XXIV for the kind of stone, type of walling an class of mortar set out in that Table:

Provided that, if class A mortar is used, such stresses may be increased to 10 per centum of the crushing strength of the stone proposed to be used, as measured on representative samples, to the satisfaction of the local authority.

TABLE XXIV
AXIAL STRESSES PERMITTED IN NATURAL STONE WALLS.

1	2	3	4	5
Kind of stone and walling	Class A	Class B	Class C	Class D
Granite ashlar	5,5	4,4	3,5	2,8
Marble ashlar	3,5	2,8	2,2	1,7
Limestone ashlar	2,1	1,7	1,4	1,1
Sandstone ashlar	1,7	1,4	1,2	1,0
All stones squared rubble	1,4	1,2	1,0	0,7
All stones random rubble	0,7	0,6	0,4	not-permitted

72. Stresses Due To Eccentric Or Lateral Forces.

(1) When the eccentric or lateral forces, together with axial loads, have to be taken into account in walls, piers or columns, the stresses shall be calculated on the assumption that the straight-line theory applies to such walls, piers or columns as are subject to bending moments, that is to say that planes in the cross-section remain places after bending.

(2) On this assumption, the maximum stresses in any part of the walls, piers or columns aforesaid resulting from eccentric loads and lateral forces, together with the axial loads, shall not exceed those set out in Table XXV:

Provided that any excess in compressive stress over that permitted for axial vertical force is due entirely to the eccentricity of forces or to lateral forces.

TABLE XXV

PERMISSIBLE STRESSES, OTHER THAN AXIAL COMPRESSIVE, IN MASONRY

1	2
Type of stress	Value of stress
Flexural compress	1,25 times the average stresses permitted for axial. vertical forces for the conditions concerned.
Tensile in panel walls where such stress is due. solely to wind forces	0,21
Tensile other than described in (ii)	0,14
Shear for class A mortar.	0,14 or 0,333 of compressive stress due to dead load if this is greater but not exceeding 0,21
Shear for class B mortar.	0,10

73. Stresses Under Concentrated Loads.

When the combined effects of axial, eccentric and lateral forces are all taken into account, the local under the ends of lintels or under column-bases or other concentrated loads shall not exceed the average stresses permitted by sections 67 to 72 for axial vertical loads alone by more than 50 per centum.

74. Reinforced-Concrete Walls And Columns.

(1) Reinforcement, mixing and placing of reinforced-concrete walls. – Reinforcing of concrete walls shall be carried out, and the concrete shall be mixed and placed, in accordance with the requirements of Chapter 3.

(2) Design and thickness of reinforced-concrete walls. -Reinforced-concrete walls shall be designed and constructed in accordance with the provisions of Chapter 3, and shall in all cases be of the following minimum thickness-

a) basement-walls and foundation-walls, 150 millimetres;

b) exterior and interior bearing-walls, 100 millimetres.

(3) The thickness of the leaves of cavity-walls shall not be less than that of brick walls under the same conditions:

Provided that-

i) where 100-millimetre thickness is required for brickwork, 75 millimetres may be used for reinforced concrete;

ii) in dwelling-houses of a height not exceeding two storeys or 7,5 metres, whichever is the lesser, leaves or cavity-walls may be less than 75 millimetres in thickness, bust shall be not less than 40 millimetres in thickness for an unsupported length not exceeding 24 times the effective thickness;

iii) in single-storey dwelling-houses, leaves of cavity-walls shall be not less than 50 millimetres in thickness for an unsupported length exceeding 24 times but not exceeding 40 times the effective thickness.

(4) Reinforced-concrete columns.- Reinforced-concrete columns shall de designed in accordance with the provisions of Chapter 3.

75. General Requirements For Reinforced Brickwork.

(1) The design of buildings and structural members in buildings constructed of reinforced brickwork shall be based on the same general principles of design and analysis as are adopted for the design of similar members and structures of reinforced concrete.

(2) The stresses in such members and structures shall not exceed the limits set out in sections 76 to 82.

76. Materials For Reinforced Brickwork.

In reinforced brickwork-

a) bricks shall have a compressive strength of not less than 14 megapascals;

b) reinforcement shall comply with the requirements for reinforcement set out in Chapter 3;

c) mortar materials shall be required by section section 5.

77. Mortar And Grout For Reinforced Brickwork.

(1)Mortar used in reinforced brickwork shall be of class A or class B.

(2)Mortar used for grouting shall be of class A or class B, with additional water in order to produce a consistency which will enable such mortar, or grout, to be poured without causing segregation.

(3)Grout shall not be used in horizontal joints.

Permissible Stresses In Reinforcement Brickwork

78. Permissible Stresses In Reinforcement Brickwork

(1) The stresses in reinforced brickwork shall not exceed, in any part, the values set out in Table XXVI .

(2) The direct compressive stress and the compressive stress due to bending in members with slenderness ratios other than 12 shall not exceed the values set out Table XXVII for the strength of brick concerned, multiplied by the factor (F) set out in Table XXVIII for the slenderness ratio of the member considered.

TABLE XXVI

PERMISSIBLE STRESSES IN REINFORCED BRICKWORK

1	2
Types of stress conditions	Maximum value of stress in megapascals
a)Compressive stress due to bending in member with slenderness ratio of 12 b)Compressive stress due to bending in member with slenderness ratio of 12	As given in table XYVII compressive strength brick concerned for class of mortar.
c) Shear stress (i) when no shear reinforcement is provided. (ii) When properly designed and anchored shear reinforcement is provided to carry all shear.	1 per centum of compression of strength of brick but exceeding 0,35 for class of mortar. Per-centum of compression strength of brick but not exceeding 1 for class of mortar
Bond stress (i) between mortar and plain bar reinforcement (ii)Before mortar and deformed bars as set out in chapter 3	0,55 for class A mortar 0,35 for class B mortar 1,1 for class A mortar 0,7 for class B mortar
e)Tensile stress in brick work	nil

79.Detailed Requirements For Reinforced-Brick Columns.

a) the total cross-sectional area of the longitudinal steel reinforcement shall not be less than 0,4 per centum of the gross cross-sectional area of the column;

b) there shall be at least one bar for each salient angle in the cross-section of the column;

c) lateral ties shall be provided of a total volume of not less than 0,4 per centum of the gross volume of the column, and shall have a diameter of not less than 6 millimetres;

d) the lateral ties shall have their ends anchored , welded together or lapped through a distance equal to 50 times the diameter of the longitudinal bars or the least lateral dimension of the column, whichever is the least.

e) The spacing of the lateral ties shall not exceed 400 millimetres or 16 times the diametre of the longitudinal bars or the least lateral dimension of the column, whichever is the least.

80. Detailed Requirements For Reinforced-Brick Walls.

In reinforced-brick walls, the following requirements shall be complied with-

a) where-

i) the stresses in bearing-walls designed in accordance with sections 75 to 82 exceed those permitted in sections 67 and 68; and

ii) such walls are required to sustain lateral forces or loads with an eccentricity greater than one-sixth of the thickness of the wall;

the bricks which compose the walls shall be slotted or grooved so as to permit the accommodation of the vertical reinforcement and its required covering of grout without relying on the vertical joints between the bricks;

b) where openings in the wall have a height greater than 12 times the width of the brickwork between openings, the walling between the openings shall be designed as a column.

81. Cover Over Reinforcement In Reinforcement Brickwork.

(1) In reinforcement brickwork, the reinforcement shall have the cover prescribed by this section:

Provided that the local authority may require a cover greater than that so prescribed where it considers that the latter is not adequate to prevent corrosion of the reinforcement under the particularly corrosive conditions which exist at the building site.

(2) The cover of mortar or grout in the joints between reinforcement and bricks shall be not less than one-quarter of the diameter of bars or thickness of strip, and in no case less than 3 millimetres.

(3) The minimum clear distance, disregarding applied surface finishes, of bar reinforcement from exterior (exposed) faces of brickwork shall be 40 millimetres.

(4) The minimum clear distance, disregarding applied surface finishes, of bar reinforcement from interior faces of brickwork shall be as follows-

a) for slabs, walls and beams, 20 millimetres or the bar diameter, whichever is the greater;

b) for columns, 25 millimetres;

c) for any structural member in contact with the soil, such as a footing, foundation or retaining wall, 75 millimeters.

82.MISCELLANEOUS REQUIREMENTS FOR REINFORCED BRICKWORK

82. (1) In reinforced brickwork, the further re- quirements prescribed in this section shall be observed.
    (2) The minimum spacing, anchorage, cranking and splicing of the reinforcement shall conform to the requirements for reinforcement of Chapter 3.
    (3) To ensure an effective bond between brick- work and mortar, bricks shall be thoroughly wetted down, but not saturated.
    (4) All joints between individual bricks, and all spaces around and between reinforcing-bars or wires, shall be completely filled with mortar or grout, the use of grout being confined to use in vertical joints.