The Ontario Building Code | Foundation Wall Drainage
9.14.2.1. foundation Wall drainage
(1) Unless it can be shown to be unnecessary, drainage shall be provided at the bottom of every foundation wall that contains the building interior.
(2) Except as provided in Sentences (4) and (5), where the insulationhttp://thehandyforce.com/insulation/" title ="Toronto home insulation">insulation on a foundation wall extends to more than 900 mm below the adjacent exterior ground level,
(a) a drainage layer shall be installed adjacent to the exterior surface of a foundationwall consisting of,
(i) not less than 19 mm mineral fibre insulationhttp://thehandyforce.com/insulation/" title ="Toronto home insulation">insulation with a density of not less than 57 kg/m3, or
(ii) not less than 100 mm of free draining granular material, or
(b) a system shall be installed that can be shown to provide equivalent performance to that provided by the materials described in Clause (a).
(3) Where mineral fibre insulationhttp://thehandyforce.com/insulation/" title ="Toronto home insulation">insulation, crushed rock backfill or other drainage layer medium is provided adjacent to the exterior surface of a foundationwall,
(a) the insulationhttp://thehandyforce.com/insulation/" title ="Toronto home insulation">insulation, backfill or other drainage layer medium shall extend to the footing level to facilitate drainage of ground water to the foundation drainage system, and
(b) any pyritic material in the crushed rock shall be limited to a concentration that will not damage the building to a degree that would adversely affect its stability or the performance of assemblies separating dissimilar environments.
(4) Except when the insulation provides the drainage layer required in Clause (2)(a), when exterior insulation is provided, the drainage layer shall be installed on the exterior face of the insulation.
(5) The drainage layer required in Sentence (2) is not required,
(a) when the foundationwall is not required to be dampproofed, or
(b) when the foundationwall is waterproofed.
(6) Where drainage is required in Sentence (1), the drainage shall conform to Subsection 9.14.3. or 9.14.4.
9.14.3. Drainage Tile and Pipe
In Plain Language
Foundation walls require drainage as set out in this article, typically a perimeter drainage system that channels groundwater away before it can pressure or penetrate the wall.
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.