The Ontario Building Code | Crawl Spaces as Warm Air Plenums
9.18.7.1. Crawl Spaces as Warm Air Plenums
(1) Only crawl spaces under 1-storey portions of dwelling units shall be used as warm air plenums.
(2) Enclosing material in crawl spaces described in Sentence (1), including insulationhttp://thehandyforce.com/insulation/" title ="Toronto home insulation">insulation, shall have a surface flame-spread rating not greater than 150.
(3) Combustible ground cover used as enclosing material in Sentence (2) shall be covered with noncombustiblematerial.
(4) Noncombustible material described in Sentence (3) shall,
(a) extend not less than 300 mm beyond the projection of a register opening, and
(b) have turned-up edges.
Section 9.19. Roof Spaces
9.19.1. venting ="http://thehandyforce.com/interior/bathroom-renovations/" title ="Toronto Bathroom renovation inspiration">venting
In Plain Language
A crawl space may serve as a warm air plenum (part of the heating distribution system) only under the specific conditions set out in this article.
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.