(1) Asbestos-cement slates shall comply with the requirements of B.S. 690 or C.A.S. 198.

(2) Slates shall be laid so that the following requirements are met-

a) each course shall overlap the second course below it by not less than-

(i) for a diamond or honeycomb pattern, 75 millimetres ; and

(ii) for rectangular pattern, 100 millimetres;

b) for diamond or honeycomb-pattern slates, the roof-slope shall be not less than 25 degrees;

c) for rectangular-pattern slates, the roof slopes shall be not less than 17 ½ degrees;

d) where additional weatherproofing is provided to the satisfaction of the local authority, the roof-slopes referred to in paragraphs (b) and (c) may be reduced.