The Ontario Building Code | Type of Granular Material
9.14.4.1. Type of Granular Material
(1) Granular material used to drain the bottom of a foundation shall consist of a continuous layer of crushed stone or other coarse clean granular material containing,
(a) not more than 10% of material that will pass a 4 mm sieve, and
(b) no pyritic material in a concentration that would adversely affect its stability or the performance of assemblies separating dissimilar environments.
In Plain Language
The granular material used around foundation drainage, such as gravel, must be of a type meeting the requirements set out in this article, ensuring it drains well without clogging.
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.