Markham radon testing and mitigation
338,503 residents. 1 in 20 homes test above the Health Canada radon guideline.
Why Markham homeowners test
Markham's mix of detached family homes in Unionville and newer townhome developments creates a wide range of radon exposure based on home type and age.
Our Markham service
- Testing: $99 (standard) or $399 (real estate)
- Mitigation: $2,800 to $3,800 preliminary estimate 3
- Typical scheduling: within 3-5 business days
- Same-week availability most months
Markham-specific questions
Do you service all of Markham including Unionville and Cathedraltown?
Yes. Every Markham neighbourhood including Unionville, Cathedraltown, Wismer, Berczy, Greensborough, Cornell, Markham Village, Thornhill (Markham side), and the Highway 7 Markham Centre area. Same $99 pricing across all of Markham.
Which Markham neighbourhoods are higher risk for radon?
Unionville and the older Markham Village core have homes dating to the 1960s and earlier, often with stone foundations. Newer subdivisions like Cathedraltown, Wismer, Berczy, and Greensborough have airtight modern envelopes which can trap radon if soil-level gas is present, even though absolute soil radon in this area is moderate.
My Markham home was built in Cathedraltown or another post-2021 subdivision. Tarion coverage?
Yes if you purchased from a builder on or after Feb 1, 2021 and your home is inside its 7-year Tarion warranty. Markham's recent inventory in Cathedraltown, Wismer, Berczy, Cornell, and Greensborough is largely within this window. C-NRPP certified test result at or above 200 Bq/m³ triggers builder-funded mitigation up to $50,000.
Are there special considerations for Markham townhomes vs detached?
End-unit townhomes have one additional foundation wall in contact with soil, which can slightly increase radon entry compared to interior units. Detached homes generally have larger basement footprints and are more likely to have finished basement living space, which increases time-weighted exposure if levels are high. We test both at the same $99 price.
About these numbers
Population and home counts come from Statistics Canada's 2021 Census of Population 1 . These are exact figures.
The per-city radon percentage is a synthesis estimate, not a number pulled directly from any single source. We blend three datasets: Health Canada's Cross-Canada Survey of Radon Concentrations in Homes (the 2012 federal baseline) 4 , the University of Calgary's Evict Radon citizen-science mapping project 2 , and Take Action on Radon's aggregated municipal data 5 .
The federal baseline often reports lower above-guideline rates than the newer citizen-science projects. Two reasons: the federal study is now 14+ years old, and the newer citizen-science projects sample more aggressively in homes built under tighter modern building codes (which trap soil gas more effectively than older draftier construction). Where these sources disagree on a specific municipality, our published percentage lands on a working midpoint. So if you click through to the federal survey expecting to find "Markham 5%" verbatim, you won't. The federal survey may report a lower figure for the same area, and the citizen-science maps often report a higher one. We chose the midpoint because no single source is definitive.
None of this gives you a definitive percentage for your specific home. Two homes on the same street can test 30 Bq/m³ apart. The only reliable answer for your home is a test on that home.
References
- 1.Statistics Canada. Census Profile, 2021 Census of Population↗ (2022)↩
- 2.Evict Radon. Evict Radon National Study↗↩
- 3.Health Canada. Government of Canada Radon Guideline↗↩
- 4.Health Canada. Cross-Canada Survey of Radon Concentrations in Homes: Final Report↗ (2012)↩
- 5.Canadian Association of Radon Scientists and Technologists (CARST). Take Action on Radon↗↩
See our full research bibliography at /sources.