What radon is and why it matters here

Radon is a natural gas that comes from soil and rock. You cannot see it or smell it. It can enter through small cracks and gaps in the lowest level of a home, then collect in still air. Calgary homes spend long months closed up for heat, which lets radon build up. Testing is the only way to know your level. The good news: if levels are high, there are proven fixes that bring them down fast.

Where radon tends to collect

Radon is heaviest near the lowest lived-in level. In most Calgary houses that means the basement or a lower family room. It can move through:

• Cracks in slabs and foundation walls
• Gaps around sump pits and floor drains
• Openings for pipes, wires, and posts
• Soil in crawlspaces without a sealed vapor barrier

Air pressure inside a warm house often pulls soil gases inward. That is why winter is a strong time for testing: the house is closed and the stack effect is higher.

Short-term vs long-term tests

There are two common ways to test:

• Short-term tests (2–7 days): helpful for a quick screen during a pre-purchase timeline. Use them to decide if a longer test is wise.
• Long-term tests (90 days or more): the best picture of real exposure. They average out daily swings from weather and house use.

If you are buying, a short test is better than guessing. If you already own, a long test through the heating season gives the clearest answer.

How to place a test the right way

Setup is simple, but a few details matter for a fair reading.

• Pick the lowest level you use often: usually a basement family room or bedroom.
• Place the device 0.8–2 m above the floor: about table height, away from floors and ceilings.
• Keep it out of dead corners: at least 50 cm from walls, not behind curtains or near a draft.
• Avoid heat and fans: no direct sunlight, no space heaters, no blowing vents right on the device.
• Normal living: keep doors and windows closed as you usually would in winter. Do not tape the house shut.

When to test in Calgary

Any time works, but winter gives strong data because houses stay closed and pressure differences pull more soil gas in. If you run a test in summer with windows open, levels may look low. A winter re-test often reads higher. Many owners test from late fall to early spring for that reason.

What the numbers mean

Test results come back as a concentration value. If your level is very low, you are in good shape. If your level is elevated, plan a fix. Think of it like this:

• Low level: keep your report, retest in a few years or after major renovations.
• Borderline: run a long-term test through winter to be sure. Small air sealing and fan use can help.
• High level: plan mitigation with a qualified installer. Modern systems lower levels quickly.

Your inspector can help you read the report in plain language and suggest next steps that match your home’s layout.

How mitigation works

The most common fix is called active soil depressurization. A small fan pulls air from beneath the slab or a membrane and vents it safely outdoors. This lowers the pressure under the floor so soil gas does not enter the living space. Key parts:

• Sealed suction point: a core hole through the slab or a connection to the sump pit (with sealing).
• Inline fan: quiet, runs continuously, usually placed in the garage or outside to keep any leaks out of the home.
• Discharge stack: vents above the roofline or high on an outside wall, away from windows.
• Sealing: cracks, joints, and the sump lid are sealed to improve system pull.

Most jobs finish in a day. Levels often drop right away, and follow-up testing confirms the result.

What mitigation does not require

You do not need to tear out finished rooms. You do not need to replace your furnace. You do not need to open every wall. The system is compact and uses little power. Many installs sit neatly in a corner of the mechanical room with a short vent run.

DIY steps that help even before a system

These do not replace a mitigation system when levels are high, but they can reduce entry paths and improve air movement:

• Seal visible cracks in slabs and along the slab-wall joint with proper sealant
• Replace an open sump lid with a tight, gasketed lid
• Add a continuous vapor barrier over bare earth in crawlspaces and seal the seams
• Run bathroom fans for 15–20 minutes after showers to keep humidity down
• Balance supply and return air so rooms do not sit under strong negative pressure

New builds and renovations

New homes can include rough-ins for radon control. If you are building or finishing a basement, ask about:

• A stubbed suction pipe under the slab for a future fan
• A sealed and gasketed sump lid from day one
• Foam and sealant at slab edges and penetrations
• Clear routes for a future vent that can exit above the roofline

Small choices during construction make future fixes cleaner and cheaper.

Condos and townhomes

Units above grade usually test lower than basements, but testing still makes sense for ground-level suites or slab-on-grade townhomes. If you live on an upper floor and get a high reading, talk to the building manager. A shared plan might help if multiple units show concerns.

How inspections and radon testing fit together

During a pre-purchase timeline, a short-term test can run while the rest of the inspection takes place. For owners, a long-term winter test pairs well with a maintenance inspection. Your report then ties air sealing notes, fan performance, and basement moisture to the radon plan. It turns a single number into a clear set of actions.

Common questions from Calgary owners

Can I just open windows? Fresh air helps in the moment, but it is not a steady fix in winter. You will lose heat and levels rise again when windows close.

Will an HRV solve it? Balanced ventilation supports good air, but it is not a dedicated radon system. It can help after a mitigation fan brings levels down.

Do I need to test every year? Many owners test again after big renovations or HVAC changes. If you installed a system, re-test once it has run for a while, then at intervals to confirm it holds.

How loud is the fan? Properly placed, most fans are very quiet. You should not hear them in living spaces.

Reading a test report without stress

A clear report includes the average level, the test window, and basic placement notes. If the average is high, do not panic. Mitigation has a strong track record. If the average is near the middle range, a longer test through winter gives the best answer. Keep the PDF with your home files and save a copy in the cloud for easy access later.

What buyers should do during a deal

If timing is tight, ask your inspector about a fast screen and a follow-up plan after closing. You can write the offer with room for a longer test later and a fair plan if the number comes back high. You do not need to walk away from a good house. You need a path that keeps health and budget in balance.

Simple checklist you can use today

• Pick a test: quick screen if buying, 90-day if you already own
• Place it on the lowest lived-in level, away from drafts and heat
• Run the test during winter for useful data
• Log start and end dates and keep normal living habits
• Read the report, then choose: re-test, small fixes, or full mitigation
• Save results with your home records and re-test after big changes

The payoff

Radon testing turns an invisible risk into a simple number and a clear plan. In a city with long heating seasons, that peace of mind is worth a weekend of setup and a little patience. If your level is high, modern systems bring it down fast. If your level is low, you have proof that your home is a safe place to live. Either way, you move forward with facts, not guesses.