The Ontario Building Code | Foundations
(1) Continuous perimeter foundation walls are not required, but when they are provided, they shall comply with the requirements of this Part.
(a) in the case of hollow masonry units, 4 times the least dimension of the units,
(b) in the case of solid masonry units or hollow units with voids filled with concrete, 10 times the least dimension of the column, or
(c) where the column is reinforced with at least four 13 mm diam bars and filled with concrete, 18 times the least dimension of the column.