Current as of August 2026. Building code requirements change, and adoption dates differ by province. Always confirm with your local building official for a permit issued today.
Short answer: yes in much of Canada, and it has been for longer than most coverage suggests. Ontario, British Columbia and Quebec each already require radon provisions in new residential construction under their own building codes. The 2025 National Building Code adds a further requirement — a passive vertical radon stack — but as a model code it applies only where adopted.
The confusion comes from two different things being called the same thing. A rough-in and a passive stack are not the same requirement.
TL;DR: Ontario (2024 OBC, in force since 1 January 2025), British Columbia (2024 BCBC, in force since 8 March 2024) and Quebec (Construction Code) all require radon rough-in provisions in new Part 9 residential construction today. Quebec goes furthest, also requiring radon test results to be submitted to the authority having jurisdiction. The 2025 National Building Code's passive-stack requirement applies where provinces adopt it, and the four largest provinces adopt on their own schedules. None of these guarantees a home is below 200 Bq/m³ — only a test after occupancy does that.
First, the vocabulary — because the levels matter
CAN/CGSB-149.11-2024, the Canadian standard for radon control in new buildings, defines the levels. Codes reference these, and knowing which level your code requires is the whole question:
| Level | What it is |
|---|---|
| Level 1a — rough-in | Gas-permeable layer, soil gas barrier and soil gas collector, connected to a solid pipe accessible above the finished floor. The pipe is capped and sealed inside the building, typically above the lowest floor. |
| Level 1b — extended rough-in | The same, but the pipe extends outside through a rim joist or sidewall. |
| Level 2 — passive stack | A vertical stack running through the building and out the roof, venting by stack effect. No fan. |
| Level 3 — active system | A fan is added, creating active soil depressurization. Now described in CAN/CGSB-149.12-2024 (mitigation of existing buildings). |
So when a headline says a radon system is "now mandatory," the useful question is: at which level?
Province-by-province status — August 2026
| Jurisdiction | In force today? | What is required |
|---|---|---|
| Ontario | Yes — 2024 Ontario Building Code, in effect 1 January 2025; all permit applications from 1 April 2025 | Part 9 residential buildings require a rough-in for a future sub-slab depressurization system. Floors-on-ground must be provided with a rough-in consisting of clean granular material and a pipe, or a proprietary system with a gas-permeable layer; minimum 100 mm (4″) pipe. Assemblies in contact with the ground must resist soil gas leakage per Subsection 9.25.3 or MMAH Supplementary Standard SB-9. Buildings occupied less than four hours a day may be exempt. Part 3 buildings are not directly linked to the Part 9 rough-in requirement, but Subsection 5.4.1 requires air barrier assemblies to minimize radon and soil gas ingress. Many municipalities require a dedicated radon rough-in inspection before the slab is poured. |
| British Columbia | Yes — 2024 BC Building Code, in effect 8 March 2024 | Subsection 9.13.4 applies province-wide (the previous code limited requirements to listed municipalities). All Part 9 buildings, residential and non-residential, intended to be occupied more than four hours in a 24-hour period require a soil gas control system: a gas-permeable layer, which may include perforated pipe below the air barrier, connected to a radon vent pipe that extends through and terminates outside the building — effectively a Level 1b extended rough-in. BC has required the vent pipe to exterior since December 2014. |
| Quebec | Yes — Construction Code; in force 8 January 2022, province-wide 2 June 2022, mandatory for all projects since 8 July 2023 | The most demanding regime in Canada. Requires the radon rough-in with stub, radon test results to be submitted to the authority having jurisdiction (generally municipal building officials), and the addition of sub-slab depressurization sufficient to reduce levels within Health Canada's guideline where testing shows it is needed. Quebec is the only jurisdiction that closes the loop from rough-in to test to remedy. |
| Alberta | Yes — confirm current edition | Alberta's building code has carried radon rough-in requirements, and several Alberta municipalities operate programs that go beyond the provincial baseline. Alberta maintains its own code based on the national model and adopts on its own schedule, so confirm the edition in force and its radon provisions with the provincial safety codes authority or your accredited municipality for a permit issued today. |
| Saskatchewan, Manitoba, New Brunswick, Nova Scotia, PEI, Newfoundland and Labrador, Yukon, NWT, Nunavut | Depends on adopted edition | These jurisdictions adopt the National Building Code, typically with local amendments, on their own schedules. What applies to your project is the edition in force in that jurisdiction on your permit date. Confirm with the provincial or territorial building standards office. |
| National Building Code 2025 | Model code — applies where adopted | Requires at least a passive vertical radon stack (Level 2) in dwelling units and home-type care occupancies — a step beyond a capped rough-in. Provinces with their own codes adopt on their own timelines; historically anywhere from a few months to five years. |
This table is current as of August 2026 and will change. The governing answer is always your authority having jurisdiction.
A note on the national baseline. The National Building Code has required a soil-gas barrier and a rough-in in new homes since 2010. The 2025 edition's contribution is raising that baseline from a capped rough-in to a passive stack — not introducing radon provisions where none existed.
For the full code history, the municipal programs that go further (Hamilton, Guelph and Kingston in Ontario), and how warranty coverage interacts with all of it, see our complete guide to Canadian building codes and radon.
The one question to ask your building official
"Which edition of the building code applies to a permit issued today in this jurisdiction, and what does it require for radon and soil gas control?"
That answer governs. Nothing on this page — or any other page — overrides it. Municipalities can also add inspection requirements: Hamilton, Ontario, for example, sets out builder and owner responsibilities for inspections covering slab perimeter sealing, soil gas barrier installation, rough-in pipe and granular material, and pipe capping and labelling before occupancy.
Where the "now mandatory" coverage goes wrong
Reporting on the 2025 National Building Code has generally described the passive stack requirement as newly mandatory across Canada. Two corrections:
- Requirements already existed. Ontario, BC and Quebec have had radon provisions in force for one to two years or longer. A builder in those provinces has been installing rough-ins for some time.
- The national code is a model. It carries legal force only where adopted, and the four largest provinces publish their own codes on their own schedules.
The accurate framing is that the 2025 NBC raises the national baseline from a rough-in to a passive stack — a real and meaningful change — and that provinces will arrive at it at different times, from different starting points.
What none of this achieves
No code provision guarantees a finished home is below Health Canada's guideline of 200 Bq/m³.
Radon levels cannot be predicted before a house is built and occupied. Two homes on the same street, built to the same plan by the same crew, can test very differently — depending on the soil beneath that specific foundation, pressure differences within the structure, and how the occupants live in it.
Every Canadian code provision addressing radon requires preparation rather than promising a result. Quebec is the exception that proves the point: it is the only jurisdiction that also requires the test. Health Canada's position is unchanged everywhere — test after occupancy, with a long-term test of at least three months during the heating season.
If you are buying or have just bought a new home
A rough-in or a passive stack in your new home is good news: it means that if your home does test high, the fix is straightforward and inexpensive rather than a retrofit project. It is not evidence that your radon level is low.
Ask the builder which level was installed — a capped rough-in (Level 1a), an extended rough-in to the exterior (Level 1b), or a passive stack (Level 2) — and where the pipe terminates. Then test after you move in, over a full heating season. If the result is above 200 Bq/m³, a certified professional adds a fan and the system becomes active. In Ontario, the new-home warranty administered by Tarion may cover radon mitigation within its warranty window; coverage varies elsewhere. See our province-by-province warranty guide and the Tarion claim guide.
Measured results by region: Canada radon map.
Common questions
Is a radon rough-in mandatory in Ontario?
Yes. The 2024 Ontario Building Code, in effect since 1 January 2025 and mandatory for all permit applications from 1 April 2025, requires Part 9 residential buildings to include a rough-in for a future sub-slab depressurization system.
Is a radon rough-in mandatory in British Columbia?
Yes. The 2024 BC Building Code, in effect since 8 March 2024, applies Subsection 9.13.4 province-wide to Part 9 buildings occupied more than four hours in a 24-hour period, and requires a radon vent pipe terminating outside the building.
What does Quebec require?
Quebec's Construction Code requires the radon rough-in with stub, submission of radon test results to the authority having jurisdiction, and sub-slab depressurization sufficient to bring levels within Health Canada's guideline where needed.
What is the difference between a rough-in and a passive stack?
A rough-in (Level 1) terminates inside the building or just outside through a sidewall. A passive stack (Level 2) runs vertically through the building and out the roof, venting continuously by stack effect. The 2025 National Building Code requires at least Level 2.
Does having a rough-in mean I don't need to test?
No. It prepares the house for a fix. Only a long-term test after occupancy establishes the actual radon level.
Who installs and inspects radon rough-ins?
C-NRPP certifies professionals under the Controlling Radon in New Canadian Homes (CRNCH) credential for specifying, installing and inspecting rough-in systems. It is the smallest certification pool in the Canadian radon industry, and demand is likely to rise as codes tighten.
What the inspection actually covers: radon rough-in inspection.
Read next
Rough-in requirements for builders · Canadian building codes and radon · Radon in new construction homes · New-home warranty coverage
RadonTest.ca provides radon testing logistics and laboratory submission. We do not perform radon mitigation, we do not install rough-in systems, and we do not interpret health risk — Health Canada is the health authority on radon in Canada. Building code requirements and adoption dates change; this page is current as of the date shown, is not legal advice, nor engineering or code-compliance advice, and your authority having jurisdiction is the governing source.
Sources
2024 Ontario Building Code (O. Reg. 163/24), Part 9 and Supplementary Standard SB-9; Home Construction Regulatory Authority (Ontario), Building Code updates; Ontario Building Officials Association, Building Code Advisory Services — soil gas barrier and radon requirements for the 2024 OBC; 2024 British Columbia Building Code, Subsection 9.13.4, and Province of British Columbia Information Bulletin B24-03 (Radon Rough-in Requirements); Code de construction du Québec; Health Canada, Radon action guide for municipalities: building codes, bylaws and provisions; National Research Council Canada, National Building Code of Canada 2025; CAN/CGSB-149.11-2024, Radon control options for new buildings; CAN/CGSB-149.12-2024; Health Canada, Canadian radon guideline; C-NRPP certification types.