How are homes currently built to mitigate radon?
The current practice and building code requirement is to seal the concrete floors that separate the ground from the home making the home ready for radon removal by adding a coarse aggregate below the basement slab, installing a collection pipe that will terminate and be capped above the sealed concrete basement slab. This would also be required for slab on grade homes or homes with crawl spaces instead of basements.
How is radon and soil gas mitigation expected to evolve?
Future versions of the building code will require passive removal of Radon gas by installing vertical vent stacks in residential dwellings where a floor assembly separates a conditioned space from the ground. This new code also requires the overlapping seams of air barriers under concrete slabs to be sealed, and clarifies the type and thickness of ballast to be applied over exposed air barriers in heated crawl spaces.
How does Radon Gas enter the home? Is some Radon Gas normal?
Some radon gas is normal and will be found in every home. As new builds have become tighter to help keep your house warm and reduce energy consumption in Canadian winters, the less ability for the radon gas in the home to disperse and dilute. The sealed basement floor is a measure to keep the radon from entering the home but in the event radon levels rise above safe concentrations, then a radon technician can tie into the rough-in pipe to exhaust the radon to the outdoors.
Future building codes appear to address this with requirements for continuous passive venting to remove radon gas from the ground beneath the home that will support the reduction of radon gas entering the living spaces within the home.
How should you test your home for radon?
According to the Canadian Cancer Society, “To test your home for radon, you can purchase a test kit at some hardware stores or online from several organizations that are working to reduce radon. You can also hire a certified professional to perform a test for you.
Radon levels are measured in becquerels per cubic metre (Bq/m3). Health Canada’s radon action guideline is 200 Bq/m3, but other jurisdictions have set different limits. The World Health Organization (WHO) recommends a limit of 100 to 300 Bq/m3 and the United States has a limit of 148 Bq/m3.
If the level of radon is above 200 Bq/m3, you should work with a C-NRPP certified professional to lower the levels in your home. Even if the radon levels are below 200 Bq/m3, you may still want to try to reduce levels to as low as reasonably achievable.”
Read more from the Canadian Cancer Society here: Radon | Canadian Cancer Society
If radon is found, is this warrantable? What are some mitigation methods a homeowner could adopt?
The presence of radon at any concentration level is not warrantable. Radon can be mitigated with existing radon rough-ins that that act to either passively or mechanically remove excess levels of radon in the home.
After the new building code comes into effect throughout 2027, there will be continuous passive venting to remove or at lease significantly reduce the concentration of radon within the home.
Read More:
Best practice requirements for both new and existing homes can be found in the 2024 versions of two standards published by the Canadian General Standards Board (CGSB)
- CGSB 149.11 Radon control options for new buildings and
- CGSB 149.12 Radon mitigation options for existing buildings
Health Canada’s Technical information on radon includes
- the ‘Radon Guideline’ for new and existing homes and other helpful resources such as the ‘Guide for radon measurements in homes’
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