New Home Radon Warranty in Ontario: What Tarion Actually Covers
If you bought a new home in Ontario after February 1, 2021, your builder may owe you a radon fix worth thousands. Most owners have no idea.
Ontario added radon to its statutory new home warranty for purchase agreements signed on or after that date. The coverage is run by Tarion. The cap is $50,000 per home.
This post is about the warranty itself. What it is, who it covers, how long it lasts, and what your builder is actually on the hook for.
The short version:
- New Ontario homes with a purchase agreement signed on or after February 1, 2021 carry radon coverage under the Tarion warranty.
- The coverage lasts 7 years from your possession date.
- A professional test at or above 200 Bq/m³ triggers it.
- Your builder pays for the mitigation system, up to $50,000.
- You only pay for the test that proves the problem.
- Resale homes and pre-2021 builds don’t qualify.
What is the new home radon warranty?
It’s a piece of Ontario’s mandatory new home warranty that makes your builder pay to fix high radon.
Every new home in Ontario comes with a warranty backed by Tarion. It covers things like defects, water leaks, and major structural problems. In 2021, the province added radon to that list.
Here’s the logic. Radon is a gas that seeps up from the soil into homes. It’s the second leading cause of lung cancer in Canada.
You don’t get cash. You get the fix. The builder hires a mitigation pro and pays the bill.
Who qualifies for the coverage
Four things have to be true. Miss one and the warranty doesn’t apply.
- Your purchase agreement was signed on or after February 1, 2021. This is the date, not your closing date. Check the contract.
- You bought from a Tarion-licensed builder. Not a previous owner. Not a flipper.
- You’re inside your 7-year window. The clock starts on your possession date.
- A professional test reads at or above 200 Bq/m³. That’s Health Canada’s action level.
The trickiest one is the date. It’s the Agreement of Purchase and Sale date that counts. Some buyers signed pre-construction deals in late 2020 for homes built much later. If you signed before February 1, 2021, you’re out, even if the house went up in 2023.
If you’re not sure, dig out your paperwork. The APS date is on page one.
The coverage windows: 1, 2, and 7 years
The Tarion warranty has three coverage periods. They protect different things and last different lengths of time.
| Window | Length | What it mainly covers |
|---|---|---|
| Year 1 | 12 months | Defects in work and materials, plus the items below |
| Year 2 | 24 months | Water penetration, major systems, some defects |
| Year 7 | 84 months | Major structural defects, and radon |
Radon sits in the 7-year window. So you have a long runway. Even if you’re four or five years in and just heard about this, you likely still qualify.
The 7-year clock starts on your date of possession. If you took possession on June 1, 2022, your coverage runs until June 1, 2029.
What Tarion covers (and what it doesn’t)
The $50,000 cap is set high on purpose. It’s meant to fully fund the fix.
| Covered | Not covered |
|---|---|
| Mitigation system design | The initial radon test |
| Sub-slab depressurization install | Resale homes |
| The mitigator’s labour and parts | Homes past the 7-year window |
| Post-fix verification test | Pre-February-2021 agreements |
| The workmanship on the system | Health costs or medical claims |
| Up to $50,000 per home | Cosmetic upgrades |
A standard sub-slab depressurization system in Ontario runs $2,800 to $3,800.
The one thing you pay for is the test. At Breathe Radon Free that’s a $99 flat fee. Think of it as the price of proof.
What your builder actually owes you
Once you have a qualifying test, the builder’s job is clear.
They have to fix the home so radon drops below the guideline. That means a real mitigation system, installed by a qualified mitigator, verified with a follow-up test.
- The builder selects and pays the mitigator.
- The mitigator installs the system, usually in one day.
- A post-fix test confirms the level dropped. A good system cuts radon by 80 to 99 percent.
- You pay nothing for the work.
A quick note on who does the fix. Under a Tarion claim, you don’t get to pick your own installer and send the builder the bill. The builder chooses. If you’d rather choose your own, you’d pay out of pocket and skip the warranty path.
For the full step-by-step on filing, see our Tarion radon warranty claim walkthrough.
DIY test vs hiring a pro
Can you check your own home first? Yes. Should you rely on it for the warranty? No.
Here’s the honest split.
Do it yourself to screen. A cheap charcoal kit or a home monitor is a fine first look. If it reads low, you can relax. If it reads high, you have a reason to test properly. A DIY kit costs $25 to $50. That’s real money saved on the first pass.
Hire a pro for the claim. Tarion needs a defensible report. That means a calibrated device, a closed-house test, and a signed report with placement and duration.
| DIY kit | Professional test | |
|---|---|---|
| Cost | $25 to $50 | $99 at BRF |
| Good for | A first screen | A Tarion claim |
| Report | Basic lab result | Signed, calibrated, dated |
| Accepted by Tarion | No | Yes |
So the smart move is often both. Screen with a kit. If it’s high, book a proper test to build your claim. You can start that on our services page.
Local angle: why this matters for new builds
Ontario builds a lot of airtight homes. Tight homes hold heat well. They also hold radon well.
Newer subdivisions across the Greater Toronto Area plus surrounding Southern Ontario are full of post-2021 builds. Places like north Oakville, Milton, and the newer parts of Mississauga have thousands of homes still inside the 7-year window.
Radon doesn’t care how new or nice the house is. Two homes on the same street can read very differently. The only way to know yours is to test it. And if yours is a covered new build, testing could unlock a builder-funded fix.
What to do next
Start with a test. That’s the whole trigger for the warranty.
If you’re a new-build owner in Ontario, here’s the simple path:
- Check your purchase agreement date. February 1, 2021 or later means you may qualify.
- Test your home. A $99 professional test gives you a report Tarion will accept.
- If it’s high, file the claim and let the builder fund the fix.
We help with all three. The test is $99. The Tarion claim support is free for test customers. You can request a quote to get started, or read the full claim walkthrough first.
For the policy side, the Government of Canada radon page is a solid read.
Frequently asked questions
How long do I have to file a radon claim on a new home?
You’re covered for 7 years from your possession date. Radon falls under Tarion’s 7-year window, the longest one. File the claim before the deadline, even if the actual install happens after.
Does the warranty pay me cash, or just the repair?
Just the repair. The builder hires and pays a mitigator to install the system and verify it works. You don’t receive money. You receive a fixed home, up to the $50,000 cap.
My home is a resale. Am I covered?
No. The radon warranty applies to the original buyer of a new build with a qualifying agreement date. If you bought from a previous owner, you’re not covered. You can still test and mitigate on your own. The Lungs Matter Grant covers up to $1,500 for income-eligible homeowners.
What radon level do I need to trigger the coverage?
At or above 200 Bq/m³. That’s Health Canada’s national guideline.
What if my builder went out of business?
Tarion still covers you. The warranty is between you and Tarion, not just you and the builder. If the builder is gone, Tarion arranges the fix under the same cap.
Book a $99 radon test and check your Tarion coverage →
Authored by the Breathe Radon Free Team. Every claim is backed by a primary source. Full bibliography at /sources.
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