The Ontario Building Code | Minimum Wall Thickness
9.20.7.2. Minimum wall Thickness
(1) Except as provided in Sentence (2) and Article 9.20.7.4., no chase or recess shall be constructed in any wall 190 mm or less in thickness.
(2) Recesses may be constructed in 190 mm walls provided they do not exceed 100 mm in depth, 750 mm in height and 500 mm in width.
In Plain Language
A minimum wall thickness must be maintained around a chase or recess, as set out in this article, ensuring enough masonry remains to carry the wall's load.
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.