The Ontario Building Code | Reduction in Thickness
9.15.4.7. Reduction in Thickness
(1) Where the top of a foundation wall is reduced in thickness to permit the installation of floor joists, the reduced section shall be not more than 350 mm high and not less than 90 mm thick.
(2) Where the top of a foundation wall is reduced in thickness to permit the installation of a masonry exterior facing, the reduced section shall be,
(a) not less than 90 mm thick, and
(b) tied to the facing material with metal ties conforming to Sentence 9.20.9.4.(3) spaced not more than,
(i) 200 mm o.c. vertically, and
(ii) 900 mm o.c. horizontally.
(3) The space between wall and facing described in Sentence (2) shall be filled with mortar.
In Plain Language
A foundation wall's thickness may be reduced under the specific conditions set out in this article, provided the reduced section still meets structural and lateral support needs.
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.