(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
*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