Radon in a Canadian home sale: when a seller must disclose, testing on a closing timeline, holdbacks, inspectors and what the evidence says about value.
Photo: Shixart1985, CC BY 2.0, cropped, via Wikimedia Commons.
Not required to sell
No province requires a radon test before a resale closes. Radon enters a sale through a seller's duty to disclose a known defect, a disclosure form, or a new home warranty.
No province requires a radon test before a resale home can close. Real estate regulators in BC and Alberta say a known high result is a defect the seller must disclose. Health Canada does not recommend testing during the sale itself. Its advice is to test before you sell, test after you buy, or use a holdback. Check the disclosure rule for your province.
The BC Financial Services Authority (BCFSA) says a known level of 200 Bq/m³ or more is a material latent (hidden) defect to disclose. BCFSA says a seller who has fixed the home does not have to raise the old level, but must answer a direct question honestly or decline to answer. The Real Estate Council of Alberta (RECA) says a seller must disclose a test over 200 Bq/m³ unless a system goes in before listing.
Radon enters a sale through a duty to disclose a latent defect, a disclosure form, or a new home warranty. Disclosure statements in Nova Scotia, New Brunswick, Quebec and BC include a radon line. The Real Estate Council of Ontario (RECO) says sellers must disclose known latent defects that make a home unsafe. RECO says TRESA Phase 2 has given agents separate disclosure duties since 1 December 2023. It says the Seller Property Information Statement is voluntary. See what Canadian law requires overall.
Health Canada says a three-month test is the only accurate way to know a home’s radon level. It does not recommend testing during a transaction. RECA notes that offer timelines move faster than a proper test. See how to run a long-term test before you sell or after you buy.
A holdback keeps part of the sale price in trust after closing. The buyer runs a long-term test. If the result comes in over the agreed threshold, the money pays for mitigation. BCFSA tells both sides to write in a fixed time limit and the exact radon threshold that releases the funds.
RECA says an Alberta buyer can lower the offer by the cost of mitigation. RECA also describes a holdback released on a low result, with the buyer testing within 90 days of possession. See what a fix costs, to help you size a holdback.
If you are selling, run a long-term test before you list, so the result is ready when buyers ask. If you are buying, run one after you move in. Test the level of the home you plan to use. BCFSA notes that a clean main-floor test says little if you plan a basement bedroom.
For a new Ontario home, a long-term test can support a Tarion claim. Tarion accepts a test by a certified professional or with what it calls an “approved do-it-yourself radon test kit”. See what a new home’s warranty covers for radon.
CARST’s real estate guideline says you still need a long-term test after possession, whatever a screening shows. The guideline sets out how a screening is done. It runs at least 4 days, with an independent C-NRPP professional, under closed-house conditions and a signed non-interference agreement. That agreement states that anyone who falsifies information in a transaction may face legal action.
4
days at leastMinimum length of a radon screening during a home sale under CARST's real estate guideline, run by an independent C-NRPP professional. A screening is not a long-term test, and a long-term test after possession is still needed.
CARST sorts a screening result into three bands.
See what a short test cannot tell you.
The authors of the 2024 Cross-Canada Radon Survey state that having high radon and getting it mitigated does not hurt a home’s value. That is the authors’ position. No Canadian study has measured radon’s effect on sale prices.
In England, when a risk map raised an area’s published radon risk, prices there fell about 1.6%. They did not recover when the risk was later lowered. See how a fix lowers radon.