Radon in BC Home Sales: What Buyers and Sellers Need to Know

Last updated: 2026-04-26

If you are buying a home in the BC Interior — Castlegar, Nelson, Kimberley, anywhere in the Kootenays — you should ask about radon before you sign. If you are selling and a recent test came back high, you have options, and most of them are easier to handle before the deal closes than after. The right time to deal with radon in a real-estate transaction is during the contract, not in court.

This post is information, not legal advice. For the contract language and disclosure obligations that apply to your specific transaction, talk to your realtor and a real-estate lawyer.

What BC's real-estate guidance actually says

The British Columbia Real Estate Association published Legally Speaking #577 — Radon: What you should know about this invisible health hazard as the standing reference for realtors on this topic. It does not set new law; it interprets existing disclosure obligations in the radon context. The short version:

• Sellers should disclose known elevated radon readings. If a property has been tested and the result was above Health Canada's 200 Bq/m³ action level, that is a material fact a court could later treat as relevant to the buyer's decision. Hiding it creates legal exposure if the buyer discovers it post-close.
• Buyers can request testing as a condition of the offer. A radon-testing condition is no different in form from a financing or inspection condition — it is negotiable, and in known-hotspot regions like the Kootenays, it is reasonable.
• The Property Disclosure Statement asks about known issues. "Are you aware of…" questions cover what the seller knows, not what they should have tested for. A seller who has never tested can honestly say "no" — which is why a buyer's own test condition matters.

If you are buying in the Kootenays

The case for asking is strong. Of homes tested locally: roughly 59% of Castlegar homes, 49–59% of Kimberley homes, and around 25% of Nelson homes came back above Health Canada's action level. Voluntary test-kit challenges over-represent suspicious cases, but the regional pattern holds across multiple sources. The Kootenays sit on uranium-bearing granitic bedrock — basement-vs-crawlspace doesn't predict risk well, and a slab-on-grade home can test as high as a finished basement.

How to actually ask:

1. Have your realtor request the seller's testing history in writing. A verbal "have you ever tested?" is not the same as a written question on the disclosure paperwork. If the seller has tested, ask for the report — the lab name, the date, the duration, and the result in Bq/m³.
2. Verify the test was a long-term test. Health Canada's gold standard is a 91-day-minimum (ideally 12-month) alpha-track detector, run during closed-window season (October–April). A 2-to-7-day short-term test is sometimes used in real-estate transactions for time-pressure reasons, but short-term variability is high. If the seller's only data is a 48-hour test from August, treat it as preliminary at best.
3. If the seller has not tested, write a testing condition into the offer. Typical structure: a 60- to 90-day window during which the buyer places a long-term detector, with a clause that allows the buyer to renegotiate or walk if the result exceeds an agreed threshold. Realtors familiar with the Interior write these conditions routinely.
4. If the result comes back high, you have three normal moves: ask the seller to mitigate and provide post-mitigation verification before close, negotiate a price reduction reflecting the $2,500–$4,500 Kootenay cost of mitigation, or take the project on yourself post-close with eyes open. Which one fits depends on the closing timeline and the seller's willingness.

One mistake worth avoiding: assuming "the inspector would have caught it." Most BC home inspectors do not test for radon as part of a standard inspection — it requires a separate process. Ask explicitly.

If you are selling and you have tested high

Disclose it. BCREA's Legally Speaking #577 is the document to point your realtor at if there is any doubt. A known elevated reading hidden from a buyer who later tests on their own is the worst-case scenario for both your conscience and your liability exposure.

The cleaner path: mitigate before listing. A C-NRPP-certified sub-slab depressurization installer can typically have a system installed and verified within 2–4 weeks. Post-mitigation systems routinely cut radon levels by 50–99% according to Health Canada's Radon Reduction Guide, and the post-install confirmation test becomes part of the marketing package.

What to keep on file for the listing:

• The pre-mitigation test result (the document showing the problem you fixed)
• The C-NRPP installer's quote, scope, and certification number
• The post-mitigation confirmation test showing the system works
• Warranty paperwork on the fan and workmanship (industry norm: 2 years workmanship, 5 years fan)

Local realtors in Nelson, Castlegar, and Kimberley report that a documented mitigation system is generally treated as a feature in known-hotspot listings rather than a defect — buyers in this region are increasingly radon-aware, and the alternative (an undisclosed problem they discover post-close) is much worse for everyone. The price impact of mitigation work tends to get recovered or exceeded in the sale.

For the technical detail on how mitigation actually works, the sub-slab depressurization explainer covers the method and variants. For the test-kit basics, the radon testing guide covers the homeowner side.

Working with a Kootenay-aware realtor

Most realtors working in Nelson, Castlegar, Kimberley, and the surrounding RDCK and RDEK areas know the regional radon picture. Some routinely raise the topic during the inspection conversation; others wait to be asked. Ask your realtor directly: "Do you typically include a radon-testing condition for Interior properties? What threshold do you write in?" The answer tells you whether they have done this before. A realtor who has never written a radon condition is not necessarily the wrong realtor — but you may need to coach them through the structure, or have your real-estate lawyer draft the wording.

FAQ

Does the BC Property Disclosure Statement require sellers to test for radon? No. It asks whether the seller is aware of issues, not what they should have tested for. A seller who has never tested can answer truthfully that they have no knowledge — which is exactly why buyers in known hotspots should request their own test as a condition.

Can I require the seller to fix elevated radon before closing? You can request it in your offer. Whether the seller agrees is a negotiation. Typical outcomes: seller mitigates and provides verification before close, seller credits the buyer for the cost of mitigation at closing, or the buyer accepts the situation and takes responsibility post-close.

How long does a real-estate radon test usually take? The Health Canada–recommended long-term test runs 91 days minimum. For real-estate timelines that cannot accommodate that, a 7-day short-term test is sometimes used as a screening, with documentation that it is a screening, not a definitive number. Some buyers add a clause requiring follow-up long-term testing post-close.

Will mitigating before I list scare buyers away? The local pattern is the opposite. In a region where roughly half of tested homes come back elevated, a properly documented mitigation system signals a seller who has dealt with the issue rather than one who is hoping the buyer doesn't ask. Keep the paperwork.

Is this legal advice? No. This article summarizes BC real-estate guidance for general information. For your specific transaction, consult your realtor and a BC real-estate lawyer.

Kootenay Energy does not handle real-estate transactions, and we don't perform radon mitigation. Our role is information and a referral pipe — we point homeowners toward BC Lung Foundation test kits and, when a result comes back high, we match them with a vetted local C-NRPP installer. The full Kootenay radon picture lives on the radon pillar page.

External authority: BCREA Legally Speaking #577, Health Canada — Radon, BCCDC Interactive Radon Map.