The Ontario Building Code | 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.