Does the New Brunswick building code require a radon rough-in or passive radon stack when finishing a new basement in a high-risk region like Fredericton?

The NB Building Code does not currently mandate a passive radon rough-in as a condition of finishing a basement, but it's one of the smartest low-cost steps you can take before closing up your walls and floor — especially in the Fredericton area.

New Brunswick follows the National Building Code of Canada (NBC), which as of the 2020 edition includes provisions encouraging radon-resistant construction in new builds, but does not universally require a passive radon stack retrofit when finishing an existing basement. That said, your local building department (the City of Fredericton has its own inspection department) may have adopted amendments or have inspectors who flag radon preparedness — it's worth a direct call to confirm what's currently enforced for your specific permit application.

What the code does require is that you test. Health Canada's guideline is clear: if radon levels exceed 200 Bq/m³, mitigation is required before the space is used as habitable area. Fredericton and the surrounding Saint John River valley have documented elevated radon readings — the geology of the region (granite and uranium-bearing bedrock) contributes to higher soil gas concentrations. Testing before you finish is not optional if you're creating a bedroom, family room, or any space where people will spend time.

Here's the practical reality: installing a passive radon rough-in (a 4-inch PVC pipe stubbed up through the slab into the sub-slab aggregate, capped above the roofline) costs roughly $200-$500 when done during a renovation before the floor and walls are closed. If you later test and find elevated levels, converting that passive stack to an active sub-slab depressurization system (adding an inline fan) costs another $500-$1,000. Compare that to installing a full mitigation system after finishing — which means cutting your new floor, running pipe through finished walls, and paying $2,000-$4,000 for the complete job. The math strongly favours roughing it in now.

Practical steps to take:

Start with a 3-month passive radon test kit ($30-$50 at hardware stores) placed in the lowest level of your home before finishing begins. If you're already mid-renovation or want faster results, a professional short-term test runs $150-$300. If results come back below 200 Bq/m³, you're clear to proceed — but still consider the rough-in as cheap insurance. If results exceed the action level, you'll need a licensed radon mitigation contractor before finishing the space.

When pulling your building permit with the City of Fredericton, ask the building inspector directly whether a passive radon stack is required or recommended under the current local amendments to the NBC. Inspectors appreciate the question and it puts you on record as doing things properly.

This is firmly in the "hire a professional" category for the actual mitigation system installation — sub-slab depressurization requires proper placement, sealing, and fan sizing to work correctly. The rough-in pipe itself can be installed by your basement contractor as part of the framing and slab work, but the full system should be done by a certified C-NRPP (Canadian National Radon Proficiency Program) professional.

New Brunswick Basements can connect you with local basement contractors who understand radon rough-in requirements as part of a full finishing project — getting matched is free.