Yovan Gabric | REALTOR®What the house is hiding
A naturally occurring radioactive gas that enters through the foundation and accumulates indoors. It is the second leading cause of lung cancer in Canada after smoking. It has no smell, no taste and no visible sign — the only way to know is to test, and testing is inexpensive.
Which homes
Where it turns up
Knowing the usual locations is enough to decide whether an assessment is worth commissioning. It is not enough to conclude that a house is clear.
A long-term test of at least 91 days during the heating season, using a certified device, is the standard Health Canada recommends. Short-term tests screen but do not conclude.
Health Canada's guideline is 200 becquerels per cubic metre. Above that, remedial action is recommended. Confirm current guidance at the time of testing.
Remediation
Required credential: C-NRPP certified for measurement, and separately for mitigation.
Active sub-slab depressurisation is the usual solution — a pipe and fan drawing soil gas from beneath the slab and venting it above the roofline
Sealing cracks and the sump lid helps but is rarely sufficient alone
A post-mitigation test is essential; the work is not finished until a follow-up test confirms the reduction
Use a professional certified under the Canadian National Radon Proficiency Program
Buying or selling
Radon is increasingly raised as a condition in Ontario transactions. A completed test with a documented result — even a high one that was then mitigated — is a stronger position than no information at all. Finish any basement only after you know the number.
Confirming the presence of radon in a specific home requires qualified professionals and, where applicable, accredited laboratory analysis. Guidelines and regulations change. Nothing on this page replaces a professional assessment, and nothing here is legal advice about disclosure obligations when selling—raise those with your lawyer.
A straightforward first conversation
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