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 metre, 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 millimetres and not more than 8 millimetres 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.