What are the radon and soil gas control requirements for new houses in Ontario?
New Ontario houses need protection against soil gas ingress: a sealed air barrier (typically polyethylene) below the slab with sealed joints and penetrations, plus provisions for a subfloor depressurization rough-in where radon is a concern in the area.
Paraphrased for clarity — open this provision in the BUILDAiD Library for the exact wording.
In practice this means sheet polyethylene under the basement slab, sealed at seams, at the sump pit, and around every pipe penetration, plus a capped radon rough-in pipe stubbed through the slab into the granular layer in designated areas. The most common inspection failures are unsealed sump lids and slab penetrations cut after the poly was placed. Coordinating the rough-in location with mechanical and future venting up through the roof saves retrofit cost if testing later shows elevated radon.
Radon is a naturally occurring gas that can seep up from soil into basements. New homes get a sealed plastic layer under the concrete floor, and in many areas a capped pipe is roughed in so a radon fan can be added easily later if needed.
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This page is provided for general information. Building code requirements depend on your specific project, occupancy and municipality, and code editions change. Always verify requirements against the current Ontario Building Code and confirm with your local building department.