Canada · Building code

What are the building code requirements for radon mitigation in Canada?

The NBC requires radon rough-in provisions in new residential construction, including a sealed sub-slab pipe stub and soil gas barrier, so that an active depressurization system can be installed if post-construction testing reveals elevated radon levels.

Radon is a naturally occurring radioactive gas that can accumulate in buildings and pose a health risk. The National Building Code addresses radon through preventive measures in new construction, requiring rough-in provisions that make it straightforward to install an active mitigation system if needed after the building is occupied and tested.

What to check first

  • New residential buildings must include a radon rough-in consisting of a sealed pipe stub through the floor slab connected to the sub-slab granular layer.
  • A soil gas barrier (sealed polyethylene membrane or equivalent) is required beneath the slab to reduce soil gas entry.
  • The rough-in allows a fan to be added later to create active sub-slab depressurization if post-occupancy testing shows radon above 200 Bq/m³.

Jurisdiction notes

National baseline

NBC Part 9 Section 9.13.4 covers soil gas control measures including radon rough-in requirements for residential buildings.

Provincial variations

Some provinces, particularly those with known high-radon areas, may have adopted stricter requirements or earlier implementation dates for radon provisions.

Health Canada guideline

Health Canada's radon guideline sets the action level at 200 Bq/m³. Building code provisions are designed to facilitate compliance with this guideline.

Not professional advice

CodeCan reports what the published building code says. It is not legal, engineering, or architectural advice, and it does not certify compliance. Building codes are adopted and amended provincially and enforced locally — always verify with your authority having jurisdiction (AHJ) before you build.

Work through it in this order

  1. Confirm whether the building type requires radon rough-in provisions under the applicable code edition.
  2. Verify the sub-slab granular layer and soil gas barrier requirements for the foundation design.
  3. Ensure a sealed pipe stub is installed through the slab, routed to allow future connection to an exhaust fan.
  4. Check whether the province or municipality has additional radon requirements beyond the NBC baseline.
  5. Plan for post-occupancy radon testing and potential activation of the depressurization system.

Common questions

Does every new house in Canada need radon protection?

Under recent NBC editions, new residential buildings require radon rough-in provisions. The specific adoption date varies by province.

What is the radon action level in Canada?

Health Canada's guideline sets the action level at 200 Bq/m³. If post-occupancy testing exceeds this level, an active mitigation system should be installed using the rough-in provisions.

Is a radon fan required at the time of construction?

No. The NBC requires the rough-in (pipe stub and soil gas barrier) so a fan can be added later if testing shows elevated radon levels.