How to choose a radon mitigation contractor

What certification should a radon contractor in Canada hold?

Health Canada recommends hiring a professional certified by the Canadian National Radon Proficiency Program, known as C-NRPPsource. That is the credential to look for in this country, and it is the only one this guide discusses.

Ask for the name of the certified individual, not only the company, and ask what kind of work the certificate covers. The reviewer of this site, for example, holds one credential for measurement and a separate one for mitigation, both listed in the next section. So ask which one the person coming to your house holds.

A firm may employ one certified professional and several helpers. That is normal. What you want to know is who designs the system, who is on site while it is installed, and whose certificate number goes on the paperwork.

How do you verify a C-NRPP certification?

Look the person up yourself, by name, in the public directory that C-NRPP maintains. It takes very little time, and a legitimate professional will expect you to do it. Check that the name matches, that the certification is for mitigation, and that it is current.

Here is what that looks like with our own installer. Systems arranged through Calgary Radon Pro are designed and installed by Plinio Neto, who holds the C-NRPP Radon Mitigation Professional certification (CRMT-202966) and the C-NRPP Radon Measurement Professional certification (CRT-202965). Both numbers can be checked in the C-NRPP public directory.

If a contractor cannot give you a name and a number to check, or the name in the directory is not the person who will do the work, treat that as an answer.

What should you ask in the first conversation?

Ask about the person, the design, the proof and the paperwork, in that order. A contractor who does this work regularly will have short, specific answers.

• Who will design the system, who will install it, and what are their C-NRPP certificate numbers?
• Which mitigation method do you expect to use in my house, and why that one?
• Where would the suction point, the fan and the exhaust go, and what are the alternatives?
• Which standard do you install to?
• How will I be able to tell, day to day, that the system is running?
• What testing do you do after installation, and what happens if the reading is still above the guideline?
• What exactly is covered if the fan fails or the outcome is disappointing, and for how long? Ask for it in writing.
• Do you carry liability insurance and workers' compensation coverage, and can I see the documents?
• Who services the system later, for example when the fan eventually needs replacing?

Have your test report beside you when you call. A serious contractor will ask how long the test ran, where the detector sat and what the number was before saying anything about a system. If you do not have a long-term result yet, our guide on how to run a long-term radon test explains how to get one.

What should happen at the site visit?

The contractor should look at the house before pricing it. Health Canada describes sub-slab depressurization as the most common and effective method, and says that more ventilation or sealing of entry routes has limited effect when used alonesource. Whether that method suits your house, and how it would be laid out, depends on things that can only be seen in person.

Expect questions and some poking around: the type of foundation, whether there is a sump pit, a crawl space or an addition, how the basement is finished, where a pipe could run and where it could leave the building. In a newer house the contractor should look for the rough-in. Alberta's building code requires a radon rough-in with a pipe stub in new homessource, and using it can simplify the job, as described on our page about activating a builder's radon rough-in.

A contractor should test how easily air moves under the slab before settling the design, or explain plainly why your house does not need it. A price given over the phone from the square footage alone is a guess.

What should a written quote include?

Enough detail that a second contractor could read it and know what is being built. The table lists what to look for.

A number that means anything comes after someone has seen the house, and what drives the cost of a radon system in Calgary is covered on its own page.

Which standard should the work follow?

The Canadian standard for mitigation in existing buildings is CAN/CGSB-149.12-2024, Radon mitigation options for existing buildingssource. A contractor should be able to name it without looking it up, and to tell you where a design choice in your quote comes from.

One place this shows up is the exhaust. The standard allows a system to discharge above the roof or through a side wall near ground level, and says the side-wall route shall be favoured in cold weather areassource. Homeowners who have read advice written for other countries sometimes take a side-wall outlet for a shortcut. In Canada it is an accepted option under the national standard. What matters is that the contractor can explain why the chosen route suits your house.

A U-tube manometer on the pipe shows the system is working: the liquid stands higher on one side because of the pressure difference the fan createssource. Ask to be shown the gauge and its normal reading before the installer leaves.

How should the result be confirmed?

By a test, every time. Health Canada reports that a system reduces radon by more than 80% in most homessource, which is a statement about most homes and not a promise about yours. A careful contractor will say so, and will not quote a final number before the work is done.

Health Canada recommends testing after a system is installed, retesting every 5 years while it is in use, and testing again after renovations that affect the structure or ventilationsource. The arrangement we use is a short verification reading taken by the installer after installation, followed by a long-term test in the heating season with an independent laboratory kit that the homeowner places and mails. The long-term one runs at least 91 days, within Health Canada's recommended 3 to 12 monthssource. Ask which of these the quote includes. Our page on how follow-up radon tests are run describes both kinds.

The reason for the independent laboratory is simple: an installer should not be the one marking the installer's homework.

Which warning signs should make you look elsewhere?

Most of them are a missing detail or a promise that is too large.

• No named certified person, or a certificate that cannot be found in the directory.
• A firm described as certified with no individual behind the claim.
• A price with no site visit and no description of the system.
• A promise of a specific final reading, or talk of removing radon entirely.
• Pressure to sign today because of immediate danger. Health Canada describes the health risk from radon as long-term, not immediatesource, and its guidance recommends acting within one year above the guideline, sooner at higher levelssource.
• Sealing or painting the floor offered as the complete fix.
• No follow-up test in the quote, or testing waved away as unnecessary.
• No gauge on the pipe and no explanation of how you would know the fan had stopped.
• Health claims that go beyond lung cancer risk, or products presented as endorsed by a government department.

None of these proves bad work on its own. Two or three together are a reason to get another quote.

How do you compare two quotes fairly?

Line them up item by item against the table above, not total against total. The cheaper quote is often cheaper because something is absent: the follow-up test, the sump lid, the electrical connection, the repair of what was opened. Ask each contractor to price the missing items so the two documents describe the same job.

Then weigh what does not fit in a column. Did the person look at the house carefully? Were the answers specific? Did they tell you what they could not promise? Work that is buried under a slab and runs unattended for years is bought largely on trust in the person who designed it.

Make sure the starting number is sound as well. The figure every quote is working against is the Canadian guideline of 200 Bq/m³ as an annual averagesource, and a long-term result is what should be compared with it. The radon test result checker shows where your number sits. If all you have is a reading from a few days, consider confirming it before you sign, unless it came back far above the guideline.

Does this checklist apply to Calgary Radon Pro?

Yes, and you should use it on us. The person who designs and installs our systems is named above, with certificate numbers you can verify. Our page on the radon mitigation service we offer in Calgary describes the methods and how results are confirmed, and the page about who we are sets out who writes and who reviews this site.

We also follow our own advice on promises. We do not quote a final radon level in advance, and we do not publish prices that have not been confirmed. Questions about insurance, compensation coverage and coverage terms deserve written answers from any contractor, and that includes us: ask for them with your quote.

If you are weighing a contractor against doing part of the work yourself, read what a homeowner can reasonably do without a contractor first. It draws the line between the jobs that suit an owner and the ones that do not.