Radon is the second leading cause of lung cancer in Canada. Many GTA homeowners are unaware their homes have elevated levels. This thread covers testing and mitigation in 2026.
Context
Health Canada action level: 200 Bq/m3. 7% of Canadian homes estimated above this level. Ontario has moderate overall risk but specific geological areas (Georgian Bay, some Durham Region) are higher. Basement-heavy GTA homes require testing.
Testing Options
DIY test kit (90-day minimum): $30-$80 from Home Depot or Amazon. C-NRPP certified professional testing: $200-$400. Long-term testing (full heating season) is most accurate and recommended for real estate transactions.
Mitigation: Sub-Slab Depressurization
Active soil depressurization (ASD): $1,500-$3,500 installed by C-NRPP certified contractor. Pipe + fan draws radon from under foundation and vents above roofline. Reduces radon 80-99% in most cases.
Test before AND after basement renovation - finishing a basement increases radon entry points.
LF Builders coordinates radon mitigation rough-in during renovation: https://lfbuilders.ca
Share radon testing experience at https://home.renovation.reviews