New homes built in Ottawa under the Ontario Building Code require three specific radon mitigation measures: installation of a soil gas barrier, rough-in for a subfloor depressurization system, and installation of a whole-house ventilation system (typically an HRV or ERV). These requirements apply to all new low-rise residential and small building construction, including additions.
However, these code-required measures don’t guarantee low radon levels—they’re designed to make future mitigation easier if needed. The soil gas barrier consists of polyethylene sheeting with lapped joints, the rough-in includes a perforated pipe below the air barrier system, and the ventilation system helps dilute indoor air. Despite these protections, Health Canada and building officials still recommend testing all homes, as actual radon levels can only be determined through proper measurement.
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