Radon mitigation in Calgary

When does a home need mitigation?

When a long-term test puts the annual average above the guideline. Health Canada's guideline for indoor air is 200 Bq/m³, and it recommends corrective action above that levelsource. The recommended window is one year, shorter for higher results, with the aim of getting radon as low as reasonably achievablesource.

Mitigation is also a legitimate choice below 200 Bq/m³. Some owners act at 150 Bq/m³ because a child sleeps in the basement, or because they would sooner not carry a result that close to the line into a future sale. What mitigation should never rest on is a guess. If the only number you have comes from a test of a few days, confirm it with a long-term test first, unless it is several times the guideline. Our page on radon levels and the Canadian guideline sets out how fast to move in each range.

How does a radon mitigation system work?

It keeps the air under the house at a lower pressure than the air inside it, so soil gas flows into a pipe instead of into the basement. Health Canada describes sub-slab depressurization as the most common and most effective method, and notes that extra ventilation or sealing on their own have limited effectsource.

The parts are few. A hole is cored through the slab and a small pit is hollowed out beneath it. A pipe is sealed into that hole and connected to an in-line fan that runs all the time. The fan pulls air from the gravel and soil under the floor and pushes it outside, where it mixes with outdoor air. A simple gauge on the pipe shows that suction is present. Cracks and open joints near the suction point are sealed so the fan pulls from the soil and not from the room.

The drawing shows the layout Plinio Neto installs most often: the fan on the pipe inside the basement, and the exhaust leaving through the rim joist at the side of the house. Our guide to how a mitigation system works goes through the physics.

The photo beside it is the same layout in an unfinished basement. The four below show it in other Calgary homes: beside a tankless water heater, next to an electrical panel, against an older concrete foundation wall and in the corner of a finished room.

Which system does my Calgary home need?

The foundation decides. A full basement on a concrete slab, the most common case in Calgary, takes a standard sub-slab system. Other foundations use the same principle with a different way of reaching the soil.

Each of these has its own page: sump pit systems, crawl space systems and rough-in activation.

How much does radon mitigation cost in Calgary?

The price follows the work. A single suction point with a short pipe run in an unfinished basement sits at the low end. More suction points, a long or awkward pipe route, a finished basement that limits access, and electrical work for the fan each add to it. A written quote comes after an on-site assessment, because the things that set the price cannot be seen from a photo of the house. Our cost guide for Calgary lists the ranges by system type and what each includes.

What does the on-site assessment cover?

Everything the design depends on. The installer looks at the foundation type and the condition of the slab, checks for a sump pit, a crawl space or an addition on a separate footing, and finds out whether the builder left a rough-in. Possible suction points are compared, along with the pipe route from each, the place for the fan, the nearest power and the spot where the exhaust can leave the house. In a finished basement the question is which closet, utility room or storage area lets the pipe pass with the least disturbance. Bring your test report: the starting level sets how much reduction the design has to deliver.

What happens on installation day?

Health Canada notes that a radon reduction system can usually be installed in less than a daysource. The work follows the same order in most houses.

1. Walk-through. The installer confirms the suction point, pipe route, fan position and exhaust location agreed at the assessment.
2. Diagnostics. A small test hole and a vacuum show how freely air moves under the slab, which settles whether one suction point will do.
3. Coring. A hole is cut through the slab and a pit is dug out under it by hand.
4. Piping. The pipe is sealed into the slab, supported and run to the fan and on to the outside.
5. Fan and power. The fan is mounted and connected, and the gauge is fitted to the pipe.
6. Sealing. Nearby cracks, the floor-to-wall joint and any open sump are sealed.
7. Start-up. The fan is switched on, suction is checked at the gauge and the system is labelled with the installer and date.

Expect some noise while the slab is cored and a little dust around that spot, which is cleaned up before the installer leaves. You can stay in the house throughout.

Where do the pipe and fan go?

Wherever the route is shortest, protected and least in your way. In many Calgary basements that means a utility room: the pipe rises from the slab beside the furnace, the fan sits on it just below the floor joists, and the exhaust passes out through the rim joist. The Canadian mitigation standard allows discharge above the roof or through a side wall near ground level, and says the side-wall option shall be favoured in cold weather areassource.

A side exhaust keeps the whole system indoors except for the last few centimetres, which matters in a climate with long cold spells: there is no exterior pipe run to collect frost. The alternative is a pipe carried up through the inside of the house to discharge above the roof line. It suits some layouts better, for example where no side wall offers a suitable outlet position. The assessment shows which routes your house allows.

What results should I expect?

Health Canada reports that, in most homes, a radon reduction system lowers the level by more than 80%source. Where a particular house lands depends on its starting level, the material under the slab and how completely openings can be sealed. Nobody can responsibly promise a final number before the fan is running, and we do not.

The target is not just to get under 200 Bq/m³. Health Canada's guidance is to bring radon as low as reasonably achievable, and a well-designed system usually goes far below the guideline.

How do you confirm it worked?

By testing again, in two stages, and the second stage is not done by us. After the system has been running, Plinio Neto takes a short verification reading with a monitor to show that the fan is pulling the level down. The confirmation that counts is a long-term test of at least 91 days in the next heating season, and for that we ask you to use an independent laboratory kit that you place and mail yourself. The result comes from the laboratory to you, not through the people who installed the system. We don't grade our own work.

If the level has not dropped enough, the cause can be found: a slab area the suction does not reach, an entry point that was missed, or a fan that needs to be a different size. The usual remedy is an added suction point or further sealing. See testing after mitigation for timing.

Is radon removal different from radon mitigation?

No, they are two names for the same service. "Removal" is the word many people search for. "Mitigation" is the accurate one, because no system takes radon to zero. It is present outdoors too, and a home's level can only be reduced, not erased. A contractor who promises complete removal is promising something that cannot be measured.

What is particular about Calgary homes?

Three things come up again and again. Most houses have full basements, and many of those basements are developed into bedrooms, offices or rental suites, so people spend long hours on the level closest to the soil. A finished basement does not prevent a system; it changes where the suction point and pipe can go.

Second, newer houses are not exempt. University of Calgary research found radon in new Canadian houses has risen since about 1980source, and much of the city's housing was built after that date. Our Calgary radon map and risk guide collects the local studies.

Third, recent builds come with a head start. Alberta's building code, the National Building Code 2023 Alberta Edition, requires a radon rough-in with a pipe stub in new homessource. A rough-in is not a working system. When a test in such a home comes back high, the stub usually makes the installation simpler.

Who installs the system, and to what standard?

Health Canada recommends hiring a professional certified by the Canadian National Radon Proficiency Program (C-NRPP)source. Systems booked through Calgary Radon Pro are installed by Plinio Neto, C-NRPP certified mitigation professional (CRMT-202966). The certification is his personally, and anyone can check it in the C-NRPP public directory.

The national standard for this work is CAN/CGSB-149.12-2024, Radon mitigation options for existing buildingssource. Ask any installer which standard their work follows and whether a follow-up test is part of the job.

What maintenance does a system need?

Very little, and most of it is looking. The U-tube gauge on the pipe, called a manometer, sits higher on one side while the fan is creating a pressure differencesource. Glance at it every month or two. Level liquid means the fan may have stopped or lost power, or the small gauge tube may have come loose. Keep the outside outlet clear of snow and ice in winter.

The fan is the only moving part and will eventually need replacing; see radon fan replacement. Health Canada recommends retesting a home with an active system every five years, and after renovations that affect its structure or ventilationsource.