Calgary and much of Southern Alberta have some of the highest radon levels in Canada, with studies suggesting roughly 1 in 6 homes test above Health Canada’s guidelines.
Radon is a naturally occurring gas formed by the breakdown of uranium in the soil beneath homes. Health Canada identifies radon as the leading cause of lung cancer in non-smokers. It’s completely invisible, odourless, and tasteless, which means the only way to know it’s present is through proper testing.
Certain soil types in Calgary and surrounding areas, including shale and clay, can contain higher concentrations of uranium. Add in long, cold winters where homes stay sealed for extended periods, along with modern construction that prioritizes energy efficiency and airtightness, and radon has more opportunity to build up indoors compared to older, draftier homes.
All new homes in Alberta are built with radon mitigation rough-ins. This typically includes a sealed membrane under the foundation, a gas-permeable layer beneath the slab, and a venting pipe that can later be activated with a fan system if elevated levels are detected.
For sellers, radon is one of those items where being proactive can make a transaction smoother. If your home has already been tested and the levels are low, that gives buyers immediate confidence. If a mitigation system is in place, it shows the issue has been identified and professionally addressed – removing a lot of uncertainty on the buyer’s side.
As of May, 2026, the Canadian guideline for radon is 200 becquerels per cubic metre (Bq/m³).
If elevated levels are known to the seller but are not properly mitigated, it can fall under Alberta’s disclosure requirements for known material latent defects, so it may need to be disclosed. On the flip side, if you’ve never tested, there’s typically nothing to disclose, but buyers may still raise the question or choose to test during their condition period.
If you’re unsure what applies to your situation, it’s always good to confirm with a real estate lawyer so everything is handled correctly from the start.
For buyers, radon is usually more manageable than it first appears. Even if elevated levels are found, this isn’t in the same category as structural issues or water damage. It’s a known condition with a clear solution. Most mitigation systems can be installed in a day, typically cost between $2,500 and $3,500 in Calgary, and are highly effective – often reducing levels by 90% or more.
Where things get nuanced is testing during a real estate transaction. The most accurate way to measure radon is with a long-term test (90+ days), ideally done over the winter when homes are sealed. The challenge is that buyers don’t have that kind of time during a 1-2 week condition period.
Short-term tests can be used instead, but it’s important to understand they provide a quick snapshot that can help inform a decision, but they’re not fully conclusive. Results can fluctuate based on weather, ventilation, and how the home is being lived in during those few days.
Buyers are often making decisions with incomplete information. A short-term test can point to a potential issue, but it’s rarely the final word. Because of that, many buyers choose to move forward with the understanding that radon, if present, is something that can be addressed after possession once a long-term test is done and can install a mitigation system if needed.
Radon doesn’t have to be something to fear, but it is something to understand and manage. There are plenty of companies that deal with it daily. When it comes to how it might show up in your real estate journey, let us be your first call!
Parker
