The Ontario Building Code | Calculation of Wall and Ceiling Areas
9.10.17.6. Calculation of wall and ceiling Areas
(1) Skylights, glazing, combustible doors, and combustible light diffusers and lenses shall not be considered in the calculation of wall and ceiling areas in this Subsection.
In Plain Language
Wall and ceiling areas are calculated per the method set out in this article, for the purpose of determining flame-spread rating compliance across a room or corridor.
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.