Radon rough-in is now required in new basement living space. What changed in Ontario's Building Code this year — and why it matters.
If you're planning a basement renovation in 2026, there's a code change worth knowing about before you finalize your permit drawings: radon rough-in is now mandatory in new basement renovations that create habitable space in Ontario.
It's a small line item on a permit set. It's also one of the most overlooked — and one of the easiest to get wrong if your contractor isn't already building it in.
Effective January 2026, updates to the Ontario Building Code and Electrical Safety Code tightened several requirements around basement living space and secondary suites. The headline change for most homeowners: any basement renovation that creates new habitable space now requires a radon rough-in — a passive vent pipe run from below the slab up through the house to the roofline, capped and ready to connect to an active mitigation fan later if a radon test ever comes back high.
You don't need to install the fan. You need the pipe in place before the slab and walls are closed up — because retrofitting one after the fact means cutting into finished concrete and drywall.
Radon is a naturally occurring radioactive gas that seeps up from the ground through cracks and gaps in a foundation. It's invisible and odourless, and Health Canada has identified it as the leading cause of lung cancer among non-smokers. Because it's heavier than air, it collects in the lowest point of a home — which, in most GTA houses, is exactly the space being renovated.
Ontario has plenty of radon-prone soil, which is why the rough-in requirement isn't just paperwork. It's a low-cost way to make a future fix simple instead of expensive.
If you're getting quotes for a basement renovation now, ask directly whether radon rough-in is included in the permit drawings and the price. It should be — it's now part of a compliant Ontario basement permit, not an optional add-on. A contractor who isn't already building this in either isn't current on the code, or is planning to have you find out the hard way at inspection.
At Desire Basements, radon rough-in is now standard on every permitted basement build, priced into the quote from the first estimate — not added as a change order once construction starts.
Radon rough-in joins the list of things a compliant basement permit already needs to account for: egress windows, fire separation, interconnected smoke and CO alarms, insulation and vapour barrier standards, and — for basement apartments — the fire and sound separation requirements between units. None of these are new for 2026, but radon rough-in is the one most likely to be missed by a contractor working from an older set of standard drawings.
It's required for basement renovations that create new habitable living space in Ontario, effective January 2026. Purely cosmetic work in an already-finished basement generally isn't affected — but any project going through permit as new living space should include it.
No. Rough-in means the pipe and cap are installed during construction so a mitigation fan can be added later if a radon test comes back elevated. It's a small cost now versus a disruptive retrofit later.
Yes. Radon rough-in is included as standard on every permitted basement build we quote — it's already in the drawings and the price before you sign.
Getting quotes for a basement renovation and want to make sure they're actually up to Ontario's 2026 code? Book a free in-home consultation — every Desire Basements quote is itemized, permit-ready, and locked before you sign.
Let our team help you build the basement or renovation you've been imagining.
Get a Free Quote
