Article 9.13.4.3. contains two sets of requirements: Sentence (2) describes the criteria for subfloor depressurization systems using performance-oriented language, while Sentence (3) describes one particular acceptable solution using more prescriptive language.
In some cases, subfloor depressurization requires a solution other than the one described in Sentence (3), for example, where compactable fill is installed under slab-on-grade construction. The completion of a subfloor depressurization system may be necessary to reduce the radon concentration to a level below the guideline specified by Health Canada.
Further information on protection from radon ingress can be found in the following Health Canada publications:
- “Radon: A Guide for Canadian Homeowners” (CMHC/HC), and
- “Guide for Radon Measurements in Residential Dwellings (Homes).”