Residential Building & Renovation
Residential Construction Requirements for Radon Gas Mitigation
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Radon is a colourless, odourless and tasteless gas that is formed naturally by the radioactive breakdown of uranium contained in soil and rock. Normally radon escapes from the ground into the air where it mixes with fresh air resulting in concentrations too low to be a health concern. However, when radon enters an enclosed space through cracks or openings in floors in contact with the ground, or through foundations, it can accumulate to higher concentrations.
According to Health Canada, long-term exposure to radon is linked to approximately 16% of lung cancer deaths in Canada and is the second leading cause of lung cancer after smoking. Canada’s radon guideline is currently 200 Bq/m³ (becquerels per cubic metre). The only way to determine if radon levels are within the guideline of 200 Bq/m³ is to carry out a test.
Residential Construction Requirements
All building permit applications for new construction, and additions to, low-rise residential buildings in the City of Hamilton are required to incorporate radon gas mitigation construction requirements in compliance with the Ontario Building Code. These requirements apply to the construction of new dwellings (including new laneway houses), and residential additions.
Building permit drawings shall clearly indicate details associated with one of three radon gas mitigation options in accordance with the Ontario Building Code (OBC). OBC Reference: Article 9.13.4.1., of Division B, and Supplementary Standard SB-9 “Requirements for Soil Gas Control”
- A 100 mm diameter grey PVC pipe rough-in, OBC Reference: Subsection 3.2., Sentences (1) through (5) of Supplementary Standard SB-9
- Minimum 150 mm granular material for a radius not less than 300 mm centered on the pipe, with the bottom of the pipe open to the granular,
- The upper end of the pipe shall be provided with a removable seal and labeled to indicate for “Radon Gas Removal Only”, and
- Mandatory radon gas testing. OBC Reference: Subsection 3.2., Sentence (6) of Supplementary Standard SB-9
Sketch Drawings for Option 1
- A soil gas barrier on the foundation walls (bituminous dampproofing), and OBC Reference: Sentence 9.13.4.2.(3), of Division B
- Under the basement floor slab using 6 mil polyethylene lapped not less than 300 mm, and OBC Reference: Figures SB-9A or SB-9B of Supplementary Standard SB-9
- Sealing along the perimeter of the basement floor slab and at all penetrations using flexible sealant (polyurethane caulking).
OBC Reference: Clause 9.13.4.2.(4)(a), of Division B, and Supplementary Standard SB-9
Note: Care must be taken when installing 6 mil polyethylene since it is prone to puncture. Please ensure the 6 mil polyethylene is adequately protected.
Sketch Drawings for Option 2
- A soil gas barrier on the foundation walls (bituminous dampproofing), OBC Reference: Sentence 9.13.4.2.(3), of Division B, and Figure SB-9A or SB-9B of Supplementary Standard SB-9
- Installation of a sub-slab depressurization system installed in accordance with Health Canada guideline “Reducing Radon Levels in Existing Homes: A Canadian Guide for Professional Contractors”,
- A properly labelled 100 mm grey PVC pipe shall be installed through the floor slab adjacent an exterior wall extending under the slab into a centrally located 150 mm thick bed of granular material, and OBC Reference: Subsection 3.2., Sentences (1)through (5) of Supplementary Standard SB-9
- Above the slab, 100 mm grey PVC piping shall be installed, extending either through the roof or the rim joist, and shall have a continuous duty centrifugal inline radon fan.
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