Radon enters Ottawa homes primarily through the foundation, where the building contacts the soil. According to Health Canada and City of Ottawa documentation, radon can seep into buildings through dirt floors, cracks in foundations or concrete, sump pumps, joints, and basement drains. In some cases, well water can also contain trapped radon, which may be released into the air when water is drawn.
A pressure differential drives the process—homes typically operate at slightly lower pressure than the surrounding soil, drawing radon gas inside. This “stack effect” is powerful in Ottawa’s climate, where heated homes in colder months create stronger upward air movement that pulls soil gases inside. Once radon enters, it can accumulate to dangerous levels, especially in lower, less ventilated home areas like basements.
Image: Health Canada, Randon and Home Health Report
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