(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.