7 Frequently Asked Questions about Radon

By Mike Holmes

Mike’s Advice / Home Safety & Maintenance

Monday, February 3rd, 2020 @ 12:00pm

I’ve been talking about radon for a few years now and I love when homeowners reach out with questions about it. It’s important to pay attention to your indoor air quality, especially if you have kids and pets living in your house. Here are some of the questions I am frequently asked about radon:


7) Do houses on a slab need to be concerned about radon?

Radon gas can migrate through plastic and concrete, so the answer is yes. Radon enters anywhere it finds an airway where the house contacts the soil. This includes cracks in foundation walls and floor slabs, construction joints, gaps around service pipes, support posts, window casements, floor drains, and sumps. If your vapour barrier membrane isn’t durable enough, it can tear during construction and radon will come in that way too.


6) Should I buy a DIY radon test kit?

The easiest way to purchase a radon test kit is online. You can also find them in some local hardware stores. Most testing kits will cost you under $50.


Remember that you will have to send your test results to a lab. Turnaround time for the lab results is usually 10 days.

You can also hire a professional to do the radon test for you. Make sure the person you hire is certified by the Canadian National Radon Proficiency Program (C-NRPP).


5) Where does radon come from?

Radon is a radioactive gas that comes from the breakdown of uranium in soils, rock, and water. In enclosed spaces like residential and commercial properties, it can accumulate to dangerously high levels. Radon is the 2nd leading cause of lung cancer after smoking. It’s a colourless, odourless gas so the only way to know how much is in your home is through testing.


Radon gas can enter your home through any opening where the house is connected to the ground. This includes cracks in your foundation, floor drains, and even your well water.


4) What’s the main difference between a short-term and a long-term test?

Short-term radon tests take less than 30 days, but should be followed up a long-term radon test which takes several months. The short-term tests should be used for initial screening only. According to Health Canada, you should be testing for at least 3 months. Radon levels can fluctuate over time (even hourly), so a long-term test is a more accurate test to know the radon level in your home. You can purchase radon tests here.


3) How often should I retest my home for radon gas?

We recommend testing your home for radon every 2-3 years. It’s not necessary to retest your home every year. It costs about $40-50 to do the radon test yourself, or about $200 if you hire a radon expert.


2) How is radon measured?

Radon is measured in units of picocuries per litre (pCi/L) in the US or becquerels per cubic meter (Bq/m3) in Canada. I actually heard from a homeowner in Ottawa whose home was tested for radon. His radon levels? 1,600 Bq/m3. 25,000 deaths in North America every year can be attributed to radon gas. Get your home tested for radon. The radon guideline set by Health Canada is 200 Bq/m3. It’s lower in the US, where the EPA action level is about 150 Bq/m3 (or 4.0 pCi/L), and the World Health Organization level is the lowest at 100 Bq/m3. The WHO states that there is no level below which radon can be considered safe. If a home is testing above these levels, you need to take action. And don’t worry, there are fixes!


1) How much does it cost to get rid of radon?

Generally, the cost for mitigating against radon is between $1,500 and $3,000. When you think about how much you spend on upgrading your finishes and making aesthetic changes to your rooms, mitigating your home against this very dangerous gas does not cost that much.



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