Last month we walked through what fails first when the cold hits. This month is about something the cold does not break at all, but quietly makes worse: radon.
By November, homes across Barrie, and Collingwood are closed up for the season. The windows stay shut, the furnace or boiler runs most of the day, and the basement becomes the rec room again. That is exactly the setting where radon builds up — and exactly why late fall and winter are the right time to find out what your level is.
Radon testing is simple, it is not expensive, and it is the only way to know. Here is how it works.
What Is Radon, And Why Does It Matter In Ontario Homes?
Radon is a radioactive gas that comes from the natural breakdown of uranium in soil and rock. It has no colour, no smell and no taste, and it can enter any home through contact with the ground.
Outdoors, it disperses harmlessly. Indoors, it can collect — through foundation cracks, gaps around service pipes, floor drains, sump pits and an unfinished crawl space. Health Canada identifies radon as the leading cause of lung cancer among people who have never smoked, and it recommends that every home in Canada be tested.
The key word is *every*. Radon levels vary from one house to the next, even on the same street. A neighbour's result tells you nothing about yours.
Why Is Late Fall And Winter The Best Time To Test?
Because that is when your house is most closed up, and radon levels tend to be at their highest.
Two things happen once the heating season starts. First, the windows stay shut, so any radon that gets in has nowhere to go. Second, a heated house acts a bit like a chimney: warm air rises and escapes at the top, and that pulls replacement air in at the bottom — including soil gas drawn up through the foundation.
Health Canada recommends a long-term test of at least three months, ideally during the fall and winter. Start a test in November and it runs through the heart of a Georgian Bay winter, which gives you a realistic picture of what your family is actually breathing during the months you spend the most time indoors.
How Do You Test Your Home For Radon?
You have two options: a do-it-yourself long-term test kit, or a radon measurement professional.
Long-term test kits are sold at many hardware stores and online. You place the detector, leave it for the full test period, then mail it to the lab for results. A few things make the result more reliable:
- Place it on the lowest level of the home where someone spends a good part of the day — a finished basement family room, a basement bedroom or a main-floor living area if there is no lived-in basement.
- Keep it away from drafts, exterior walls, heat sources, the sump pit and humid rooms like bathrooms and laundry rooms.
- Leave it undisturbed for the full test period, and note the start and end dates exactly.
- Follow the kit's instructions for placement height and return shipping.
If you would rather have it done for you, look for a professional certified under the Canadian National Radon Proficiency Program (C-NRPP).
What Do Your Radon Results Mean?
Results in Canada are reported in becquerels per cubic metre (Bq/m³). Health Canada's guideline is 200 Bq/m³.
If your long-term result is above that guideline, Health Canada recommends taking steps to reduce it — and the higher the number, the sooner it recommends acting. If your result is below the guideline, you are in good shape, but it is worth retesting after any major change to the house: a basement renovation, new windows, a new heating system or significant foundation work can all change how air moves through the home.
What About Cottages And Seasonal Properties?
Test the building under the conditions in which people actually use it.
Cottage that is closed up and unheated from Thanksgiving to May is not being lived in during the heating season, so a winter test there does not reflect anyone's real exposure. But many cottages around Blue Mountain and the lakes are now four-season properties, used most winter weekends or converted to a full-time home. If yours is heated and used through the winter, it deserves a long-term winter test the same as your house in town.
If you are planning a winter conversion — insulating a three-season cottage, finishing a lower level, adding a heat source — test after the work is done. Tightening a building changes how it breathes.
Call 705-797-2311 or visit 🌐 ontariohomechecks.ca to book your home inspection with AmeriSpec of Barrie & Collingwood.