The Ontario Building Code | Flame-Spread Rating of Interior Surfaces
9.10.17.1. Flame-Spread Rating of interior Surfaces
(1) Except as otherwise provided in this Subsection, the exposed surface of every interior wall and ceiling, including skylights and glazing, shall have a surface flame-spread rating of not more than 150.
(2) Except as permitted in Sentence (3), doors need not conform to Sentence (1) provided they have a surface flame-spread rating of not more than 200.
(3) doors within dwelling units, other than vehicle garage doors, need not conform to Sentences (1) and (2).
In Plain Language
Interior surfaces must meet flame-spread rating limits set out in this article, controlling how quickly fire could travel across a wall or ceiling finish.
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.