Radon in Calgary homes: test before you finish the basement

What radon is

Radon is a colourless, odourless radioactive gas that comes from the natural breakdown of uranium in soil. It can enter a home through foundation cracks, floor drains and gaps around pipes, and it tends to build up in basements and lower floors.

How common it is in Calgary

A University of Calgary study of more than 2,300 Calgary-area homes found that one in eight exceeded Health Canada's guideline. Homes built in the previous 25 years had up to 30% higher radon than older homes, so a new or recently renovated home is no guarantee of low levels.

The guideline and the test

Canada's radon guideline is 200 becquerels per cubic metre (Bq/m³). Above that level, Health Canada recommends taking corrective action within a year, and sooner the higher the reading.

The only way to know your level is to test. Health Canada recommends a long-term test of at least three months, ideally during the heating season when windows stay closed. Long-term test kits are inexpensive and widely available.

Why test before you renovate

The most common fix, sub-slab depressurization, draws radon from under the basement slab and vents it outside through a pipe and fan. It is far simpler to route that pipe before walls and ceilings are finished. Newer Alberta homes are built with a radon rough-in pipe under the slab, which makes adding a fan straightforward.

If you are planning a basement development, start a test the winter before construction, or ask your designer to plan a route for mitigation either way.

Building it into the plan

Kay2 plans basement developments around what is under the slab as well as what goes on top of it. Bring your radon results to your consultation and we will design around them.