The Ontario Building Code | Flame-Spread Ratings
9.10.21.6. Flame-Spread Ratings
(1) Except in dwelling units and except as provided in Sentence (2), the surface flame-spread rating of wall and ceiling surfaces in corridors and walkways, exclusive of doors, shall not exceed 25 over not less than 90 per cent of the exposed surface area and not more than 150 over the remaining surface area.
(2) Except within dwelling units, corridors that provide access to exit from sleeping rooms and that have a fire-resistance rating of not less than 45 min shall have a flame-spread rating conforming to the appropriate requirements in Subsection 9.10.17.
In Plain Language
Flame-spread ratings for this occupancy or configuration are set out in this article, applying the Code's general flame-spread control principles to this specific situation.
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.