The Ontario Building Code | Bonding
9.20.9.3. Bonding
(1) Where wythes are bonded together with masonry units, the bonding units shall comprise not less than 4 per cent of the wall surface area.
(2) Bonding units described in Sentence (1) shall be spaced not more than 600 mm vertically and horizontally in the case of brick masonry and 900 mm o.c. in the case of block or tile.
(3) Units described in Sentence (1) shall extend not less than 90 mm into adjacent wythes.
In Plain Language
Masonry wythes must be bonded together as set out in this article, ensuring the layers act as a unified structural assembly rather than independent, unstable layers.
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.