How much for a radon mitigation system in an Ottawa basement?

Radon mitigation in Ottawa typically costs between $1,500 and $3,500 installed, with most homeowners paying around $2,000–$2,500 for a standard sub-slab depressurization system.

Radon is a serious concern in Ottawa and the surrounding region — Health Canada data consistently shows that Eastern Ontario has elevated radon levels compared to the national average, making this a worthwhile investment for local homeowners. The good news is that mitigation systems are highly effective, typically reducing radon levels by 80–99% when properly installed.

The most common and effective solution is sub-slab depressurization (SSD), which involves drilling a small hole through the basement slab, inserting a pipe, and running it to an exterior-vented fan that draws radon gas out from under your foundation before it can enter the home. The system runs continuously and quietly, and most homeowners never notice it after installation. Installation typically takes one day.

What affects the price in the Ottawa market comes down to a few key factors. Homes with poured concrete slabs are generally easier and less expensive to work with than those with rubble stone or block foundations, which may require additional sealing work. The routing of the pipe matters too — a simple exterior run is cheaper than threading through finished walls or mechanical rooms. If your basement is already finished, expect costs toward the higher end of the range. Some homes with very high radon readings (above 600 Bq/m³) may need multiple suction points, which adds cost.

Testing before and after is essential. A long-term radon test (90 days minimum, using a certified Health Canada detector) should be done before installation to confirm you have a problem, and again after installation to verify the system is working. Test kits run $30–$60, or you can hire a certified C-NRPP professional to test for $150–$300. Health Canada's action level is 200 Bq/m³ — if you're above that, mitigation is strongly recommended.

This is not a DIY project. Radon mitigation should be performed by a C-NRPP certified mitigator (Canadian National Radon Proficiency Program). Improper installation can actually make radon levels worse by creating negative pressure issues or bypassing the problem area entirely. In Ontario, the work should also comply with the Ontario Building Code's requirements for soil gas control.

Radon mitigation is separate from the basement finishing work Ottawa Basements specializes in, so we'd recommend finding a C-NRPP certified radon professional for the mitigation system itself. That said, if you're planning a broader basement renovation — finishing the space, adding a secondary suite, or addressing waterproofing — it makes sense to coordinate radon mitigation before finishing work begins, since access to the slab is much easier in an unfinished basement. If you're planning a basement renovation alongside your radon concerns, contact Ottawa Basements for a free consultation and we can help you sequence the work properly.