How do I test for radon in my Ottawa basement?

Testing for radon in your Ottawa basement is straightforward and something every homeowner should do — Ottawa sits in one of Canada's higher-risk radon zones, making this a genuinely important step.

Radon is a naturally occurring radioactive gas that seeps up from the soil and can accumulate in basements and lower levels of homes. It's colourless, odourless, and the second leading cause of lung cancer in Canada after smoking. Health Canada's action level is 200 Bq/m³ — if your basement tests above this, mitigation is strongly recommended.

The two main testing options are short-term and long-term detectors. For the most accurate results, Health Canada recommends a long-term alpha track detector, which you place in your basement for a minimum of 3 months (ideally over the heating season — November through March — when windows are closed and radon concentrations are highest). These detectors cost roughly $30–$50 and are available at Home Depot, Canadian Tire, or through Health Canada's online resources. Short-term electronic monitors (like the Airthings Wave) cost $150–$300 and give continuous readings, which many homeowners find useful for ongoing peace of mind, though they're considered less definitive than long-term tests.

Ottawa-Specific Context

Ottawa and the surrounding region fall within Health Canada's Radon Potential Zone, with elevated geological risk due to local granite and soil composition. Studies have found a meaningful percentage of Ottawa homes exceed the 200 Bq/m³ action level — higher than the national average. This isn't a reason to panic, but it is a reason to test rather than assume you're fine.

For placement, put the detector in the lowest livable level of your home — your basement — away from exterior walls, drafts, and high-humidity areas. Keep it at least 50cm from the floor and 20cm from walls. Leave it undisturbed for the full testing period, then mail it to the lab included with the kit.

What Happens If Levels Are High?

If your results come back above 200 Bq/m³, the good news is that radon mitigation is very effective. The most common solution is sub-slab depressurization — a licensed radon mitigation contractor installs a pipe and fan system that draws radon from beneath your foundation and vents it outside. In Ottawa, this typically costs $1,500–$3,000 depending on your foundation type and home layout, and can reduce radon levels by 80–99%.

If you're planning a basement renovation or finishing project, this is actually the ideal time to address radon — mitigation systems are easier and less expensive to install before walls go up, and it's a smart addition to any basement finishing scope.

For a free consultation on your basement project — including how radon mitigation can be incorporated into a renovation — feel free to reach out to Ottawa Basements. We're happy to walk you through the options.