How often to retest for radon
An old PDF does not follow a renovation. A tighter house can pull harder on the soil. A system that was fine can drift.
Three moments
- After the fan is installed, to confirm the lived-in room dropped. The U-tube shows suction, not becquerels.
- After air-sealing, new windows, or basement work.
- A few years later, if a system is in place, to see that it still does the job.
Use 91 days in the heating season. If the new number is still over 200, go back to the installer with the report. Above 200.
The 4-day test is a first reading. The 91-day test is the length Health Canada uses to judge a full heating season. Both are $59 before tax. Shipping, the prepaid return, and the lab are included. Tax is extra. The PDF report is emailed within 2 business days after the lab receives the detector.
Above 200 Bq/m³, the fix is a fan that pulls soil gas from under the slab and exhausts it above the roof. Radon Gas is C-NRPP certified for testing and for mitigation, and ships kits across Canada. Start from the Canada test page.
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