Tarion Radon Warranty Claim: Step-by-Step for Ontario Homeowners
About 500,000 Ontario homes are sitting inside a builder-funded radon warranty right now. Most owners don’t know it exists.
Tarion’s radon coverage was added to Ontario’s statutory new home warranty for purchase agreements signed on or after February 1, 2021. The cap is $50,000 per home. The standard mitigation job costs $2,800 to $3,800. Math checks out.
This post walks you through who qualifies, what the claim looks like, what documents Tarion needs, and what to do when a builder drags their feet.
The short version:
- Eligible homes were bought from a Tarion-licensed builder on or after February 1, 2021, inside a 7-year warranty window.
- A C-NRPP certified test that reads at or above 200 Bq/m³ triggers the coverage.
- The claim is filed through Tarion’s MyHome portal as a statutory warranty claim.
- Tarion gives the builder 30 days to respond. Most builders comply.
- The builder hires a C-NRPP CRMT certified mitigator and pays for the install.
- Coverage is capped at $50,000, which covers essentially every real mitigation job.
Who qualifies for Tarion radon coverage
Four boxes have to tick. All four. If you miss one, the coverage doesn’t apply.
1. Your Agreement of Purchase and Sale was signed on or after February 1, 2021.
That’s the date the radon clause entered Ontario’s statutory new home warranty.
The date that matters is the APS date, not your closing date or possession date. Check the contract.
2. You bought the home from a Tarion-licensed builder.
Not from a previous owner. Not from a flipper. From the original builder.
Ontario requires every residential builder to register with Tarion. You can look up your builder in the public Tarion builder directory. If they’re listed, you’re fine.
Self-built homes and homes from unlicensed contractors don’t qualify.
3. You’re still inside your 7-year warranty window.
The 7-year clock starts on your date of possession. If you took possession on April 15, 2022, your warranty runs until April 15, 2029.
Most homeowners we work with are well inside this window. The earliest possible expiry is February 2028 (a home with a February 2021 APS that closed quickly).
4. A C-NRPP certified test reads at or above 200 Bq/m³.
This is the action threshold from Health Canada’s national guideline.
The test has to be done by a C-NRPP certified professional. DIY charcoal kits from Canadian Tire don’t qualify, even if the result is the same. Tarion needs a professional report with calibration data.
Hit all four boxes? You’re eligible. The next steps are about evidence and timing.
What Tarion’s $50,000 covers (and doesn’t)
The coverage cap is generous. It’s set high to keep the actual mitigation work fully funded.
| Covered | Not covered |
|---|---|
| Mitigation system design | The initial test that proved high radon |
| Sub-slab depressurization install | Resale homes (purchased from a previous owner) |
| C-NRPP CRMT mitigator’s labour and parts | Homes outside the 7-year window |
| Post-mitigation verification test | Self-built or unlicensed-contractor homes |
| Workmanship warranty on the system | Health-related claims or medical costs |
| Up to $50,000 total per home | Cosmetic or aesthetic upgrades |
The $50,000 cap is well above the actual cost of a typical Ontario install. A standard sub-slab depressurization system runs $2,800 to $3,800.
You pay one thing out of pocket: the $99 test that documents the problem.
The test result Tarion needs
Tarion is specific about test quality. The result has to be defensible.
What the report has to show:
- A C-NRPP certification number for the tester (CRT for measurement)
- The device serial number and most recent calibration date
- The test duration (minimum 91 days for long-term, or a continuous radon monitor short-term protocol)
- The placement location (lowest occupied level, away from drafts and windows)
- The average concentration in Bq/m³
- A signed report identifying the tester and the home
A short-term test using a continuous radon monitor (CRM) under closed-house conditions for at least 72 hours is the fastest path. Health Canada’s measurement guide permits this approach for transactions and warranty claims.
Long-term tests (91+ days) are more accurate but slower. For a warranty claim with a clear deadline, the short-term CRM path is usually the right call.
Our $99 test is exactly this. Calibrated CRM, placed for 3 to 7 days under closed-house conditions, signed report ready to file. See our services for the full process.
How to file the claim
There’s no “radon form” with its own number. You file through Tarion’s standard statutory warranty process, just with radon-specific evidence attached.
Step 1: Log into MyHome
MyHome is Tarion’s homeowner portal. Account creation uses your enrollment number, which came with your closing package. If you can’t find it, call Tarion at 1-877-9-TARION to recover it.
Step 2: Start a new statutory warranty form
Inside MyHome, open a new claim under the Statutory Warranty category. Radon falls under the 7-year structural and major systems coverage that Ontario added in 2021.
Step 3: Describe the issue
Use plain language. Example:
“A C-NRPP certified short-term radon test conducted at the lowest occupied level of my home, [date range], returned an average reading of [X] Bq/m³, which is above Health Canada’s 200 Bq/m³ guideline. I am requesting radon mitigation under Ontario’s statutory new home warranty radon provision.”
Attach the signed test report as supporting documentation. PDF is fine.
Step 4: Submit
Tarion logs the claim, assigns a file number, and notifies your builder. You get an email confirmation.
Step 5: Wait for the builder’s response
Tarion gives the builder 30 days to acknowledge the claim and propose a remediation plan. Most builders respond promptly because their Tarion enrollment is on the line.
Step 6: Track the work
The builder hires a C-NRPP CRMT certified mitigator. The mitigator visits, designs the system, and installs it. Typical timeline from approval to install is 2 to 4 weeks.
Step 7: Verify the result
After install, the mitigator runs a post-mitigation test (paid by the builder, not you). A good system drops indoor radon by 80 to 99 percent.
Handling builder pushback
Most builders cooperate. A small number try to delay, dispute, or downplay the result. Know the playbook.
”Your test isn’t valid”
This is the most common pushback. The fix is choosing a tester whose credentials are bulletproof from day one.
A C-NRPP certified report with a current calibration certificate is hard to dispute. If the builder still pushes back, Tarion can require a confirmatory test by an independent C-NRPP certified third party. The result almost always confirms the first.
”200 Bq/m³ is just a guideline, not a hard limit”
True in general. Not true here.
The Tarion warranty language ties coverage to the Health Canada guideline of 200 Bq/m³.
”You opened windows / ran a fan during the test”
This is why closed-house conditions matter. A proper test includes a documented closed-house period (windows shut, HVAC normal, no fans pointed at the device). The professional tester documents this in the report.
If your tester followed Health Canada’s measurement guide,
”The radon is from your renovations / lifestyle”
Builders sometimes try to argue that homeowner changes (a basement finish, an HRV install, a new sump pump) caused the radon, not the building itself. Tarion’s position is that any radon level at or above the guideline triggers coverage, regardless of what’s behind it, inside the 7-year window.
”We’ll send our own contractor instead of a C-NRPP CRMT”
Push back hard. The Tarion warranty path requires a C-NRPP CRMT certified mitigator.
If you hit any of these and the builder keeps stalling, Tarion has a conciliation process you can request. Tarion sends an independent inspector, makes a determination, and the determination is binding on the builder.
What to do if you’re approaching the 7-year deadline
The clock matters. If your warranty is close to expiring, move fast.
A test takes 3 to 7 days. Tarion’s claim review takes about 30 days. Mitigation install takes another 2 to 4 weeks. Total elapsed time from “I should test” to “the system is in” is roughly 5 to 12 weeks.
If your possession date was, say, March 2022, and it’s now May 2029, you have about 10 months left. Plenty of time. Don’t wait.
If you’re inside the last 6 months of the window, file the claim before the deadline even if the mitigation install will happen after. Tarion’s coverage applies to claims filed during the warranty period. The install can take place after.
Document everything. Keep the test report, the claim confirmation, all email correspondence with Tarion and the builder, and copies of the mitigation contract once it’s signed.
Common scenarios
”I’m in my Year 1 walkthrough. Should I test now?”
Yes. Your first year is the easiest time to file any warranty claim. Tarion’s first-year coverage is broader than year-7 coverage, but radon specifically falls under the 7-year clause regardless.
The point is: testing in year 1 keeps you ahead of any builder dispute about cause. A fresh-build high reading is hard to blame on the homeowner.
”I’m in Year 5 and just heard about this coverage”
You still have time. The full 7-year clock applies. File a test, then file the claim. Many of our claim customers were 4 to 6 years into the warranty before they learned the coverage existed.
”I closed in 2020 but the build was after February 2021”
Check the APS date, not the closing date. If you signed before February 1, 2021, you’re out, even if the home wasn’t built yet. If you signed after, you’re in.
This catches some buyers who signed pre-construction agreements in late 2020.
”I bought from a builder who has since gone out of business”
Tarion still covers you. The warranty is between you and Tarion, not directly between you and the builder. If the builder is gone, Tarion pays the mitigator directly under the same $50,000 cap.
”My home is from before 2021, but the builder is still in business”
The statutory radon warranty doesn’t apply to your home. Your builder isn’t on the hook.
You can still mitigate at your own cost. The Lungs Matter Grant covers up to $1,500 for income-eligible homeowners.
How Breathe Radon Free fits
We’re an Ontario-based testing service, owner-led, based in Guelph and serving the Greater Toronto Area plus surrounding Southern Ontario.
For Tarion warranty claims specifically, here’s what we do:
- $99 test with a C-NRPP certified report Tarion will accept. Calibrated continuous radon monitor, 3 to 7 day closed-house protocol, written report.
- Free claim filing support. We provide a template and walk you through the MyHome submission. No extra charge for test customers.
- No mitigation upsell on a Tarion claim. When Tarion covers it, your builder picks the mitigator. We don’t compete for that work.
Our published pricing:
- Residential test: $99 flat. 3 to 7 days, written report.
- Real estate test: $399. Faster turnaround for closing timelines.
- Long-term test: $299. 91-day alpha track.
- Mitigation install: $2,800 to $3,800. Outside a Tarion claim, if you choose us as the mitigator.
- Tarion claim help: free for test customers.
The Government of Canada publishes a useful radon overview if you want the policy framing. The Canadian Cancer Society covers the health side.
See our Tarion landing page for the visual flowchart, or request a quote to start the process.
Frequently asked questions
How long does the whole Tarion radon claim take, start to finish?
About 5 to 12 weeks from your first call to a fully installed system. The test itself is 3 to 7 days. Tarion review is 30 days. Mitigation install is 2 to 4 weeks. Most of the time is waiting, not work.
What if my radon test reads above 600 Bq/m³? Does that change the claim?
The claim process is the same. Health Canada recommends faster mitigation for very high readings, so the timeline may compress.
Can I choose my own mitigator and bill Tarion?
No. Under a Tarion warranty claim, the builder selects and pays the mitigator. You don’t get to pick, and you don’t pay. If you want to choose your own installer, you’d pay out of pocket and skip the warranty path.
If the builder picks a mitigator you have concerns about (not C-NRPP CRMT certified, or poor reviews), you can raise it with Tarion. They can require a different installer.
Does Tarion cover the cost of my $99 test?
No. The test itself is your out-of-pocket cost. Tarion’s coverage starts at the mitigation work. Think of the $99 as the “evidence” cost.
What if my builder refuses to do the work?
File a conciliation request with Tarion. An independent Tarion inspector visits, makes a determination, and the determination is binding. If the builder still refuses, Tarion pays the mitigator directly and goes after the builder.
In practice, this is rare. Most builders comply once Tarion confirms the coverage.
Is there any reason NOT to file a Tarion radon claim if I qualify?
The only reason we’ve seen homeowners hesitate is fear of damaging the relationship with the builder for future warranty issues. Reasonable concern.
Tarion’s coverage exists exactly to remove that pressure. Filing a radon claim doesn’t affect your other warranty rights. And the builder is legally protected from retaliation under the warranty plan.
Book a $99 Tarion-eligible radon test →
Authored by the Breathe Radon Free Team. Every claim is backed by a primary source. Full bibliography at /sources.
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