(1) General.- Galvanized-steel roofing-sheets shall be not less than 0,55 millimetre in thickness, and the coating shall comply with the requirements of S.A.B.S. 934, Hot-dip (galvanized) zinc coatings on steel sheet and strip.

(2) Corrugated galvanized-steel roofing.- Corrugated galvanized-steel roofing shall comply with the following requirements-

a) except as provided for in paragraph (b), the roof slope shall be not less than 12½ degrees, and the minimum side-laps and end-laps of the sheets shall be in accordance with Table II;

TABLE II
MINIMUM SIDE-LAPS AND END-LAPS FOR CORRUGATED GALVANIZED-STEEL SHEETS ON ROOFS

b) where additional weatherproofing, such as the use of an under felt on timber boarding or caulking of the joints, or other method approved by the local authority, is provided, the slope of roof may be less than 12½ degrees , and the roof-slope in that case shall be not less than 7 degrees.

(3) Flat galvanized-steel roofing.- Flat galvanized-steel roofing shall be laid on a deck complying with the requirements of paragraphs (c) of section 12, except that timber decks may be unwrought and butt-joined.

(4) Galvanized-steel fluted (inverted box-rib) roofing.- Galvanized-steel fluted roofing shall comply with the following requirements-

a) the roof-slope shall be not less than 1 degree with the sheets seam-bolted together at all side-laps with galvanized seam-bolts or not less than 6 millimetres diameter and the minimum side-laps and end-laps of sheets and the maximum seam bolting centres shall be in accordance with Table III;

TABLE III
MINIMUM SIDE-LAPS AND END-LAPS AND MAXIMUM SPACING OF SEAM-BOLTS FOR GALVANIZED FLUTED SHEETS ON ROOFS

b) sheets lad at a slope of less than 5 degrees shall have the end-laps scaled with an approved sealing compound.