Radon for home inspectors

Does a home inspection measure radon?

No, unless a measurement is ordered as separate work. Nothing seen on the day reveals radon. It is a radioactive gas formed as uranium in soil and rock breaks down naturally, and it is colourless, odourless and tastelesssource. A clean, dry, well-finished basement looks exactly the same whether its air is low or high.

That gives the inspector a clear line to hold. Your notes can cover the visible condition of any radon equipment. A measurement is a different service, done with a detector over time and reported in Bq/m³. Saying so in the report protects the client from reading silence as a clean result.

What can an inspector note about an existing radon system?

Five things, all of them observations and none of them a verdict: whether a fan is running, what the gauge shows, whether the system carries a label, where the exhaust ends, and whether a pipe is only a capped rough-in.

Visible damage belongs in the same notes: a cracked fitting, a disconnected pipe, a sump lid left unsealed. Describe it and recommend that the client have the system looked at by a mitigation professional. There is a separate page on radon fan faults and replacement for clients whose fan has stopped.

Knowing our layout may help you recognize one of our systems when you meet it. The fan is mounted on the pipe indoors, in the basement. The discharge is at the side wall through the rim joist or, where the layout calls for it, above the roof by way of an interior route. The system is labelled with the installer and the date. Systems built by others may be arranged differently, and your note simply records what is there.

What does the gauge on the pipe show?

It shows that the fan is pulling, and nothing else. A U-tube manometer fitted to the pipe indicates that the mitigation system is working, since a higher liquid level on one side shows the pressure difference the fan createssource.

Two cautions follow for report writing. First, the gauge has no radon scale, so the numbers printed beside the tube are not a result and should not be copied down as one. Second, level columns are worth recording, yet they do not identify the fault. The fan may have stopped, or the small tube feeding the gauge may have come loose. "Gauge showed no pressure difference at the time of inspection; recommend evaluation" is accurate in both cases. A diagnosis is not needed from you, and none should be implied.

The exhaust is the other item clients ask about, usually because it is not where they expected. Under the Canadian mitigation standard a system may discharge above the roof or through a side wall near ground level, and the standard says side-wall discharge shall be favoured in cold weather areassource. A pipe that ends low on a side wall is therefore not, on that ground alone, a defect. Whether a particular outlet is well placed is a question for a mitigation professional and not for a visual check.

What does a capped pipe in the basement floor mean?

It means the builder left a provision for a future system. It is not a system. The National Building Code – 2023 Alberta Edition, which is Alberta's building code, requires that new homes be provided with the rough-in for a radon extraction system, described as a capped, labelled pipe through the floor opening into granular material beneath itsource. That rough-in, the Canadian standard for new buildings states, is not a complete radon control system, but it allows for easier conversion to one in the future should that become necessarysource.

Age gives a rough expectation of whether you will find one. Alberta's 2014 building code added protection against soil gas for new buildings and became mandatory at the end of its transition period on November 1, 2015; a project whose building permit application had already been received could still be built under the previous codesource. The date that matters is the permit application, not the year the house was finished, so a missing stub in a house from that period is not, by that fact alone, evidence of anything.

The useful sentence for a client is short: the pipe is capped, no fan is attached, and it does not lower radon as it stands. A buyer who was told the home "has radon protection" may be hearing this for the first time. Details of the conversion are on the page about turning a capped rough-in into an active system.

Does a radon test belong in the inspection visit?

Not if the purpose is to learn the home's level. Health Canada does not recommend that a radon test be conducted during a real estate transaction, the reason being that a three-month test is the only way to accurately find out a home's radon levelsource. When your visit is part of a purchase, that advice covers the days you are in the house.

A buyer may still want a short reading with an electronic radon monitor. We will place a screening monitor if a buyer asks, and we describe it as screening only. A reading of a few days falls far short of the 91 days below which Health Canada does not recommend testingsource. In an inspection file, such a figure belongs under a heading of its own, with its dates and its room, apart from what you observed of the equipment.

If a client asks you to arrange such a reading, the fair description is "a short screening measurement that does not replace a long-term test". Anything stronger promises more than the method can deliver. The limits are written out for buyers under radon testing when a Calgary home changes hands.

What measurement should you point the client to?

A long-term test after they move in, timed to take in the heating season. The advice Health Canada gives buyers is a long-term radon test, conducted once they have moved into the new homesource. It recommends measuring for 3 to 12 months, with a minimum of 91 dayssource, and asks that at least 91 days of the test fall in the heating season, when windows are closed and indoor radon tends to be highestsource.

You have just walked the house, so you are well placed to mention where the detector is likely to go. Health Canada's guide puts it in a regularly occupied room, used 4 or more hours a day, on the lowest lived-in level, about 30 cm or more from the floor and away from walls, kitchens, bathrooms, laundry rooms, vents, heat sources, direct sun and electronicssource. A basement bedroom or a lower-level office qualifies. A furnace room does not.

On devices, keep to the federal list. Health Canada's long-term recommendation names two types of passive device, alpha track detectors and electret ion chambers, and adds that electronic radon monitors are also usedsource. The client can have a detector placed and documented by a measurement professional, as set out under our long-term radon test for Calgary homes, or follow the step-by-step guide to testing a house with a mail-in kit. The overview of every method is on the Calgary radon testing page.

What wording suits the inspection report?

Short, factual lines that separate what you saw from what was not measured. These are our own practical suggestions. Your association's standards of practice and your own judgment decide what your report says.

• No radon measurement was performed as part of this inspection.
• A radon mitigation system was observed, with the fan running at the time of the visit.
• The gauge on the system pipe showed a pressure difference when it was viewed.
• A capped radon rough-in pipe was observed in the basement floor, with no fan connected to it.
• Records of past radon tests and of the system installation should be requested from the seller.
• A long-term radon test after possession is recommended, in line with Health Canada's advice to buyers.

Lines to leave out are the ones that sound like a level: that the home "has no radon issue", that the system "keeps radon low", that a newer house "should be fine". Each is a measurement claim made without a measurement.

Why does the age or type of house not replace a test?

Because no feature you can inspect predicts the number. Radon levels vary from house to house, similar houses next door to each other included, and testing is the only way to be sure of the level in any one of themsource. A tidy new basement and a damp old one therefore earn the same line in your report: no radon measurement was performed.

Recent construction is no comfort either. The 2017 southern Alberta study found that homes built in 1992 or later averaged 31.5% more radon than older homes, 142 versus 108 Bq/m³source. An inspector who is asked "is this a radon area?" has one sourced figure to offer. About 1 in 6 houses in the Calgary area (15.5%) were at or above 200 Bq/m³ in the Cross-Canada Survey of Radon Exposuresource. The question for this address is still open. A client who wants the rest of the research can be sent to our summary of what studies have found in Calgary homes.

Who does the measurement and the mitigation, and how is that verified?

A person holding the relevant C-NRPP certification, whose number anyone can check. Health Canada recommends that radon work go to a professional certified by the Canadian National Radon Proficiency Program, known as C-NRPPsource. C-NRPP provides a public search tool to find certified professionals, along with a certification check that confirms an individual's certification from the certification numbersource.

For an inspector the check has a second use. A system label or a seller's invoice may carry a name and a certification number. Copy both into your notes exactly as they are written, and the client can look them up later. At Calgary Radon Pro the two certifications belong to Plinio Neto: C-NRPP Radon Measurement Professional (CRT-202965) and C-NRPP Radon Mitigation Professional (CRMT-202966). You or your client can confirm them in the C-NRPP directory of certified professionals. If you refer clients to anyone for radon work, checking the number first is a reasonable habit, and our guide on picking a radon contractor sets out what else to ask.

Whether we can share a report with you is for the client who ordered the test to say. Ask us through the contact form and we will tell you plainly what we can do.

What happens if the client's long-term result is high?

That is a matter for the owner and a mitigation professional, and your part ended with the recommendation to test. Indoor air in Canada is held against a radon guideline of 200 Bq/m³, and Health Canada recommends corrective action when the annual average is above thatsource.

Health Canada's call to act covers results over the guideline. For a result under it the owner decides, knowing that lower is better and that no level is treated as risk-free. Our page on the Canadian guideline and its ranges explains the bands, and the result checker tool places a single number.

You may meet the same house again, this time with a system in it. The records to ask about are then different. A properly documented job leaves two results behind: the installer's short reading, which is a first check and no more, and a long-term report from an independent laboratory whose kit the owner placed and posted. The second is the one to look for, because the company that built a system should not be the one to mark it. Health Canada also recommends retesting homes with active mitigation systems every 5 years, and testing again after any renovation that affects the structure or ventilation of the homesource, so the date on the latest report is worth writing down. The design side is covered on our radon mitigation page for Calgary.