The Ontario Building Code | Fire Block Materials
9.10.16.3. Fire Block Materials
(1) Except as permitted in Sentences (2) and (3), fire blocksshall be constructed of materials that will remain in place and prevent the passage of flames for not less than 15 min when subjected to the standard fire exposure in CAN/ulc-S101, "Fire Endurance Tests of building Construction and Materials".
(2) Fire blocks are deemed to comply with Sentence (1), if they are constructed of not less than,
(a) 0.38 mm sheet steel,
(b) 12.7 mm gypsum wallboard,
(c) 12.5 mm plywood, OSB or waferboard, with joints having continuous supports,
(d) 2 layers of 19 mm lumber with joints staggered, or
(e) 38 mm lumber.
(3) 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.