The Ontario Building Code | Thickness of Interior Walls
9.20.6.3. Thickness of interior Walls
(1) The thickness of loadbearing interior walls shall be determined on the basis of the maximum lateral support spacing as provided in Sentences 9.20.10.1.(2) and (3).
(2) The thickness of interior non-loadbearing walls shall be,
(a) determined on the basis of the maximum lateral support spacing as provided in Sentences 9.20.10.1.(2) and (3), and
(b) in any case, not less than 65 mm.
In Plain Language
Interior masonry walls have their own thickness requirements set out in this article, generally less demanding than exterior wall requirements given reduced weather exposure.
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.