If your radon test result came back above the Health Canada guideline of 200 Bq/m³, your next question is probably: how much will it cost to fix? Here's a realistic breakdown of radon mitigation costs in Ontario, what affects pricing, and how to find the right contractor.
Typical Cost Range in Ontario
For a standard residential radon mitigation system in Ontario, expect to pay between $2,000 and $4,000 CAD. The most common factors that influence where you land in that range include:
- Foundation type: Homes with a standard poured-concrete basement slab are typically the easiest and least expensive to mitigate. Homes with stone foundations, crawl spaces, or multiple foundation types cost more.
- Home size and complexity: Larger homes or homes with additions built on separate foundations may require multiple suction points.
- Accessibility: If the contractor needs to route piping through finished spaces or work around obstacles, labour costs increase.
- Location: Pricing can vary between the GTA, Eastern Ontario, Northern Ontario, and other regions based on contractor availability and travel.
What You're Paying For
A typical sub-slab depressurization (SSD) installation includes:
- Diagnostic testing to determine the optimal suction point location
- Core drilling through the basement slab
- PVC piping routed from beneath the slab to the exterior of the home
- An inline radon fan mounted on the exterior piping (rated for continuous outdoor operation)
- System monitoring — most contractors include a U-tube manometer or electronic monitor so you can confirm the system is running
- Sealing of major cracks and gaps in the foundation (sump pit covers, floor cracks, pipe penetrations)
The fan runs continuously and uses approximately $30–$60 per year in electricity — comparable to leaving a light bulb on.
Other Mitigation Options
Heat Recovery Ventilator (HRV): An HRV increases fresh air exchange in your home, diluting indoor radon. HRVs cost between $2,500 and $5,000 installed, but they're less targeted than SSD systems and may not reduce radon as effectively in homes with very high levels. They do offer the added benefit of improved indoor air quality overall.
Sump pit modification: If your home has an open or poorly sealed sump pit in the basement, sealing and venting it can sometimes reduce radon significantly. This is usually part of a broader SSD installation rather than a standalone fix.
Crawl space solutions: Homes with crawl spaces may require a depressurization membrane installed over the soil, connected to a fan and exhaust pipe. Costs are similar to standard SSD, sometimes slightly higher due to the additional membrane work.
Is It Worth the Investment?
Health Canada recommends corrective action for homes above 200 Bq/m³. A typical sub-slab depressurization system costs $2,000–$4,000 and, according to Health Canada, can reduce radon levels by more than 80%. Fans typically last 10–15 years before needing replacement ($200–$400 for the fan itself).
From a real estate perspective, having a documented radon test and mitigation system can also be a selling point. As radon awareness grows in Ontario, more buyers are asking about radon during the home inspection process.
Finding a C-NRPP Certified Contractor
Always hire a C-NRPP (Canadian National Radon Proficiency Program) certified radon mitigator. C-NRPP certification means the contractor has completed specific training in radon mitigation and follows established Canadian protocols.
Tips for choosing a contractor:
- Get 2–3 quotes from different certified contractors
- Ask about their experience with your foundation type
- Confirm they'll provide a post-mitigation guarantee — ask whether the contractor offers a post-mitigation guarantee to achieve levels below 200 Bq/m³
- Ask about fan warranty and what happens if the system needs adjustment
- Check for reviews and references from other Ontario homeowners
You can search the C-NRPP directory at c-nrpp.ca to find certified mitigators near you.
RadonTest.ca does not endorse or evaluate individual mitigation contractors.
Municipal Rebate Programs
Some Ontario municipalities offer radon-related incentive programs. For example, the City of Guelph has historically partnered with organizations to offer subsidized radon testing. Check with your local public health unit to see if any rebate or testing programs are available in your area.
Start With Testing
Before you invest in mitigation, you need to know your home's radon level. A long-term test of 91+ days is the most reliable way to find out.
Order a RadonTest.ca kit — includes the alpha-track detector, lab analysis by our C-NRPP and ISO 17025 certified lab partner (Lex Scientific), 10 email reminders to keep you on track, and results delivered with clear Health Canada context. See our FAQ for process details.