The short answer
A high radon reading is a negotiating point, not a dealbreaker. Unlike wiring or plumbing, radon doesn't affect your insurance or your mortgage, and the fix is a standard system that reliably brings levels down. Read the full guide to radon.
Why radon is so common, and so fixable
Radon seeps up from the ground, so any home can have it, new or old, Health Canada estimates a meaningful share of Canadian homes test above the 200 Bq/m³ guideline (recent figures suggest as high as roughly 1 in 5 in some regions). The point isn't the prevalence; it's that a high reading is settled with a cheap test and a routine fix, not a decision to walk.
What testing and mitigation cost
A DIY long-term test kit is about $30 to $60; a professional test is more. If you're above the guideline, a certified mitigation system (a sub-slab vent fan) typically runs ~$2,500 to $3,500 and brings levels well down. That's your negotiating number, small, predictable, and permanent.
When to pay a little more attention
Radon is worth taking seriously (not walking, just handling) when the reading is very high, when the basement is or will be a bedroom or full living space, or when you want confirmation, in which case pay for a certified long-term test rather than relying on a quick one. The health risk is real over years of exposure, which is exactly why fixing it is worth it.
How to handle it in your offer
- Make a radon test a condition of the offer where timing allows, or test right after closing.
- If it's high, get a mitigation quote from a C-NRPP certified professional.
- Use the quote to negotiate a credit or have the seller install the system.
- Re-test after mitigation to confirm the level dropped.