Radon is a gas you cannot see, smell or taste. It comes from uranium in the ground, and it can enter any home through the floor and the foundation. The only way to know a home's level is to test it, and the fall is the best time to start. In this post, we walk you through what radon is, what Health Canada's guideline says, how to test a home you already live in, and how to plan radon protection into a new house or multiplex, when it is easiest and costs the least to add.
Every fact below comes from Health Canada's radon pages and the BC Centre for Disease Control, read on November 4, 2026. This post is about planning your home. A question about your own health belongs with your doctor.
Health Canada's factsheet Radon: What you need to know explains it. Radon is a radioactive gas that comes from uranium in the ground. Outdoors, it mixes with the air and stays at levels too low to matter. Indoors, it can build up.
It enters a building through:
- cracks in foundation walls and floor slabs,
- construction joints,
- openings around water pipes and support posts,
- floor drains and sumps, and
- empty spaces in walls.
Health Canada says levels are generally highest in basements and crawl spaces, because they are closest to the ground and the least ventilated.
The health risk is long-term. Health Canada says radon is the number one cause of lung cancer in people who do not smoke, and estimates that 16 percent of lung cancers come from radon exposure, more than 3,000 deaths in Canada each year. People who smoke and are exposed to radon face a higher risk. The longer the exposure to high levels, the greater the risk.
Health Canada also says 1 in 5 homes in Canada have high radon levels, and that all homes have some radon.
The BC Centre for Disease Control says some areas of BC have naturally higher radon than others because of geology, and that many of these areas are in the Interior and the North. It then adds the point that matters for a Vancouver family: indoor radon can vary widely from building to building, even in the same neighbourhood. Its advice is to test your home even if you live in an area with generally lower radon.
The BCCDC publishes an interactive map of indoor radon readings from homes across BC. It shows what others have measured. Your own home's level comes from a test in your home.
Health Canada's radon guideline is 200 becquerels per cubic metre (Bq/m³), measured as an average over the year. The page sets out four recommendations:
- Take corrective action if the average annual level is above 200 Bq/m³ in the normal occupancy area of a building.
- Act sooner the higher the level is. Health Canada recommends action within 1 year for a home above the guideline.
- Reduce the level as much as is practicable, which Health Canada explains as what standard methods can achieve at a reasonable cost.
- Build new buildings with methods that keep radon out and help remove it later if needed.
Health Canada says the risk below the guideline is small, but that no level is risk free, and that each homeowner decides what level they accept.
The "normal occupancy area" is any part of a building where a person is likely to spend more than 4 hours a day. Health Canada names a finished basement with a family room, guest room, office or workshop, and a basement apartment. It excludes a crawl space, an unfinished basement, and rooms that are closed off or used rarely, such as a cold room, storage room, furnace room or laundry room.
For a Vancouver family, that list matters. A basement suite rented to a tenant or used by a grandparent is in the normal occupancy area. So is a ground floor home in a multiplex, which sits closest to the soil.
Health Canada's factsheet says radon levels in a home can vary over time, so you need a long-term test of at least 3 months, ideally in the fall or winter. That makes November a good month to start a test in Vancouver.
There are two ways to do it:
- A Do-It-Yourself Kit. Health Canada says you can buy a long-term test kit and place it yourself, then send it to the lab at the end of the test period.
- A Certified Professional. A measurement professional certified under the Canadian National Radon Proficiency Program (C-NRPP) can run the test for you.
Place the test in the lowest room where someone spends more than 4 hours a day. In a house with a basement suite, that is usually the suite.
Health Canada's factsheet Reduce radon in your home sets out the options.
This is the method Health Canada calls the most effective. A pipe goes through the foundation floor and draws radon from under the home. A fan on the pipe runs all day and night and vents the radon outdoors. Health Canada says this can lower radon by 90 percent or more, and that a system can usually be installed in less than a day. A C-NRPP certified professional adjusts it to your foundation: a slab, a crawl space or a sump pit.
A heat recovery ventilator or energy recovery ventilator brings in fresh air and removes stale air, and some radon with it. Health Canada says these systems are less effective than soil depressurization, generally lowering radon by 20 to 50 percent, and that they must run all the time and be well maintained. Sealing cracks and gaps around pipes helps them work.
Health Canada lists three steps after a system is installed:
- A certified professional runs a short-term test once the system is on.
- You do a long-term test in the first heating season, in the same place as the original test.
- You inspect and maintain the system, and retest every five years.
This is where a new house or multiplex has the advantage. Health Canada's factsheet says the best chance to protect a home from radon is while it is being built, and that radon mitigation costs less to install at that stage. It recommends that all new homes include a passive soil depressurization system.
A passive system, also called a passive radon stack, is a pipe that runs from beneath the foundation to an exhaust point above the roof. Air moves up the pipe on its own and carries radon outdoors before it enters the home. Health Canada says it can lower radon by 40 to 90 percent, and that it can be upgraded to an active system by adding a fan if a test shows more reduction is needed.
Health Canada's guideline page makes the same point for every new building: use methods that keep radon out and help remove it after construction if needed.
For a new Vancouver house or multiplex, the decisions that affect radon are made in the design stage:
- The Pipe Route. The pipe needs a path from under the slab to the roof. Plan it inside a closet or a wall stack, the same way you would plan a plumbing vent, so it does not end up in a living room corner.
- Space and Power for a Fan. Leave room along the pipe, and an electrical outlet nearby, so a fan can be added later without opening finished walls.
- The Slab and Its Openings. Sealing the joints and the openings around pipes and drains in the slab closes the paths Health Canada lists.
- The Ventilation System. If your new home will have a heat recovery ventilator, keep in mind that Health Canada counts balanced ventilation as a way to lower radon as well as bring in fresh air.
- One Pipe or Several. In a multiplex where each home has its own slab area, ask your designer how many pipes the layout needs.
The City of Vancouver applies its own Building By-law, and we did not read its radon requirements for this post. Ask the City what the by-law requires for your project, and treat Health Canada's recommendation as the standard to plan to.
Health Canada says that if your new home has a passive radon stack, an active system or a heat recovery ventilator, you should still do a long-term test of at least 91 days during the heating season to confirm the level is below 200 Bq/m³. Our post on the first year in a new multiplex has a season by season list, and a radon test fits into the first fall.
When we build a new home for a family, we think about the people on every floor. In a multigenerational multiplex, the ground floor home may be planned for grandparents, and a basement suite may house a tenant or an adult child. Those are the rooms closest to the soil. Costar's process page describes how our team works with your designer or architect from the first drawings. That is the time to settle the radon pipe route, the fan space and the slab details, while they are lines on a plan.
If you are planning a new house or multiplex and want to talk through radon and ventilation, our team is happy to help. Tell us about your project today. Book a consultation.
Related on this site: Custom home construction in Vancouver · Multiplex construction in Vancouver · Heat pumps for a new home · Book a one-hour project consultation
