The Ontario Building Code | Required Fire Blocks in Wall Assemblies
9.10.16.2. Required Fire Blocks in wall Assemblies
(1) Except as permitted in Sentence (2), fire blocks shall be provided to block off concealed spaces within wall assemblies, including spaces created by furring,
(a) at each floor level,
(b) at each ceiling level where the ceiling contributes to part of the required fire-resistance rating, and
(c) at other locations within the wall, so that the distance between fire blocks does not exceed 20 m horizontally and 3 m vertically.
(2) Fire blocks required in Sentence (1) need not be provided, if,
(a) the insulated wall assembly contains not more than one concealed air space and the horizontal thickness of that air space is not more than 25 mm,
(b) the exposed construction materials within the space are noncombustible, or
(c) the exposed construction materials within the space, including insulationhttp://thehandyforce.com/insulation/" title ="Toronto home insulation">insulation, but not including wiring, piping or similar services, have a flame-spread ratingof not more than 25.
In Plain Language
Fire blocks are required within wall assemblies as set out in this article, preventing the hollow cavity inside a wall from acting as a chimney for fire spread.
This is a plain-language summary of the 2012/2017 Ontario Building Code text above, for general understanding only and not a substitute for the Code. Always confirm current requirements against the 2024 edition (O.Reg. 163/24) or a qualified professional before construction.