9.10.16.3.

(1) Except as permitted in Sentence (2), fire stops shall be constructed of,

(a) not less than 0.38 mm sheet steel,

(b) not less than 6 mm asbestos board,

(c) not less than 12.7 mm gypsum wallboard,

(d) not less than 12.5 mm plywood, OSB or waferboard, with joints having continuous support,

(e) no fewer than 2 layers of 19 mm lumber with joints staggered,

(f) not less than 38 mm lumber, or

(g) materials conforming to Sentence 3.1.11.7.(1).

(2) In a building permitted to be of combustible construction, semi-rigid fibre insulation board produced from glass, rock or slag, is permitted to be used to block the vertical space in a double-frame wall assembly formed at the intersection of the floor assembly and the walls, provided the width of the vertical space is not more than 25 mm and the insulation board,

(a) has a density not less than 45 kg/m³,

(b) is securely fastened to one set of studs,

(c) extends from below the bottom of the top plates in the lower storey to above the top of the bottom plate in the upper storey, and

(d) completely fills the nominal gap of 25 mm between the headers and between the wall plates.