Radon testing for Calgary real estate

What does Health Canada say about radon tests during a home sale?

It advises against them. In its brochure Radon in real estate, Health Canada says it does not recommend conducting a radon test during a real estate transaction, and gives the reason: a three-month test is the only way to accurately find out what the radon level is in a homesource. A purchase does not leave room for a measurement of that length. No instrument, however well calibrated, turns a brief visit into a season of data.

So this page is organised around that advice, and not around what is convenient to sell in the middle of a deal. Sellers measure before they list. Buyers measure after they move in. Anything done in between is a rough screen at most, and we say so in writing whenever we are asked to do one.

The two steps that matter most each have a page of their own: long-term radon testing for a Calgary home and radon mitigation by a certified professional.

Why can a few days of measuring not settle the question?

Because indoor radon rises and falls, and the guideline is written for the long run. Canada's guideline for radon in indoor air is 200 Bq/m³, and Health Canada recommends corrective action when the annual average is above itsource. The measurement it recommends lasts from three to twelve months, with 91 days as the minimumsource, and it does not recommend testing for any period shorter than thatsource.

Outdoor temperature, wind, air pressure and furnace use all push the level around from one day to the next. A brief reading may land in a quiet stretch or a rough one. Either way it describes those days and no others. A buyer who relies on it is relying on the weather that happened to arrive with the monitor.

Local numbers make the problem sharper. In the Cross-Canada Survey of Radon Exposure, about 1 in 6 Calgary-area houses were at or above 200 Bq/m³, and a further 36.9% measured between 100 and 199 Bq/m³source. A large group of homes here sits close to the line, which is exactly where a brief reading is least able to say which side the yearly figure falls on. Levels also vary from one house to another, even between similar houses next door to each other, and testing is the only way to be sure of a home's levelsource. The street, the builder and the year of construction do not stand in for a measurement of the house itself.

What should a seller do before listing?

Test early, while there is still a season to spare, and deal with a high result before the sign goes up. Health Canada advises sellers to test, and to mitigate if necessary, before selling, so that a low radon level can be presented as a feature of the homesource.

The seller is the one party with enough time. Someone planning a spring listing can set a detector out in the autumn and hold a laboratory average before the photographs are taken. That report answers a buyer's question with the kind of measurement the guideline is written for. A reading taken in a hurry by either side cannot do the same job.

A high average is not a reason to keep quiet about the house. It is a repair to schedule, and it is easier to schedule when no closing date is pressing on anyone. Once a system is in, our installer takes a short verification reading. The long-term confirmation is done with an independent laboratory kit that the homeowner places and mails. We don't grade our own work, and a buyer can see that from the paperwork.

Keep the file together afterwards: the first test report, the installer's name, the installation date and the confirmation result. A seller who can hand over that folder has little left to explain.

What should a buyer do instead of testing during the deal?

Plan the real test for after possession, and use the purchase period to gather what is already on record. Health Canada advises buyers to conduct a long-term radon test once they have moved into their new homesource.

Waiting is less of a compromise than it sounds. Radon has a well-understood repair, so learning the level after the keys change hands does not leave a new owner stuck. It leaves them with a measurement taken in the rooms they really use, under their own heating and ventilation habits, across a cold season. The previous household may have kept the basement for storage. Yours may sleep there. Only a test run during your own occupancy reflects that.

Two things can still happen before the sale closes. A buyer who wants something written into the agreement can ask their realtor about a hold back, described in the next section. A buyer who wants to know what the house already has on file can make the checks set out further down, none of which needs a monitor.

What is a hold back, and where does radon come into it?

It is an arrangement some real estate professionals use so that testing can take place after the sale is complete. Health Canada notes that, in some cases, real estate professionals use a hold back to allow for radon testing once a transaction is complete, and that mitigation is paid from the held-back funds if a high level is foundsource.

We pass that on as a description of what some professionals do, and as nothing more. Whether a hold back suits a particular purchase, how it is worded, how much is set aside, who holds the money and when it is released are questions for the buyer's realtor or lawyer. This company measures and mitigates radon. It does not give legal advice. We attribute no other guidance on negotiation to Health Canada, and we offer none of our own.

Our part, if the parties choose that route, is narrow and practical. We can place a long-term detector after possession, return the laboratory report, and prepare a written mitigation quote if the average is high. What an agreement does with those documents is for the people who drafted it.

What can a buyer check during the purchase without a test?

Three things: paperwork, equipment and, in a newer home, the rough-in. These checks are our own practical suggestions. They do not come from the Health Canada brochure.

An existing long-term report. Ask the seller whether the home has been tested, and ask for the report itself, not a figure recalled from memory. Read four items: the start and end dates, the room, the device and the result. A laboratory average from a lived-in room on the lowest level, taken over a heating season, tells you far more than anything that can be arranged during a sale. A report that predates a basement renovation or a new furnace describes a house that has since changed.

An existing mitigation system. Look for a pipe rising from the basement floor or the sump, and a fan along it. Listen for the fan. Then read the gauge. A U-tube manometer on the pipe indicates whether the system is working: liquid standing higher on one side shows the pressure difference created by the fansource. Columns sitting level suggest the fan is not drawing. Ask for the records as well: the installer, the date, and the results from before and after the work. Bear in mind that the gauge shows suction, not radon. Only a test shows the level, and for equipment that looks neglected there is inspection and repair of an inherited radon system.

A capped rough-in. Alberta's building code, the National Building Code – 2023 Alberta Edition, requires new homes to be provided with the rough-in for a radon extraction system: a capped, labelled pipe through the floor that opens into granular material beneath itsource. Listings sometimes describe that pipe as radon protection. It is not. A capped stub moves no air and lowers nothing. It is a provision for a future system, and it can shorten the job if the long-term test later comes back high. The details are on the page about turning a builder's rough-in into a working system.

Is a short-term screening test during a purchase still worth doing?

Only as optional screening, and only when everyone who reads the result understands its limits. It is never a substitute for the long-term test after possession.

Here is what it is. A measurement professional leaves a calibrated electronic radon monitor in one room on the lowest lived-in level, with the house kept closed, and collects it a few days later. The device stores a reading at regular intervals, so the report shows a curve as well as an average. Short-term radon tests typically last between two and seven dayssource, and Health Canada does not recommend testing for periods under 91 dayssource.

The result is a snapshot. It can read high or low against the average a full season would give, and nothing in the report can tell you which.

• What it can tell a buyer: the concentration in that room during those days, and whether the logged curve looks undisturbed.
• What it can suggest: a reading far above the guideline is hard to put down to weather alone, so it is a reason to start the long-term test promptly after moving in.
• What it cannot tell a buyer: the annual average, or whether the home sits above or below the guideline over a year.
• What it must not be used for: treating a low reading as proof that the house needs no further testing.

If you still want one, we will do it, and the limits above are printed at the top of the report. Screening monitors are placed by Plinio Neto, who holds the C-NRPP Radon Measurement Professional certification (CRT-202965). Health Canada recommends hiring a professional certified by the Canadian National Radon Proficiency Programsource, and either party can look him up in the C-NRPP directory of certified individuals before reading his report.

How does the long-term test work once you have moved in?

One small detector goes into a room you use, stays through the first heating season, and is then read by a laboratory. No fewer than 91 days of that test should fall within the heating season, when windows are closed and indoor radon tends to be highestsource. Buyers who take possession in summer lose nothing by waiting for the furnace months. A note in the calendar for the autumn is enough.

Choose the room by how your household lives, not by how the sellers lived. If a bedroom, a home office or a playroom is going downstairs, the detector belongs there. The laboratory returns one average for the period, and that figure is the one to hold against the guideline. You can have the detector placed and documented for you, as described under how our long-term radon test is run, or place a mail-in kit yourself; the Calgary test kit page compares the options.

The request form on this page books that test. Tell us the possession date and which level of the house you plan to use, and we will suggest a start date that fits the season.

What if the result after possession is above the guideline?

Then you plan a repair, calmly and with a deadline measured in months. Above 200 Bq/m³, Health Canada recommends mitigating within one year, and sooner the higher the level, with levels reduced as low as reasonably achievablesource. It also notes that a radon reduction system can usually be installed in less than a day and, in most homes, reduces radon by more than 80%, at a cost comparable to other common home repairssource.

The design depends on the foundation, the slab and what lies under it, so it starts with a visit and a written quote. Our Calgary radon mitigation page explains the method, and the breakdown of mitigation costs shows what moves a quote up or down. After installation the same rule applies to you as to a seller: a short verification reading from the installer, then a long-term kit from an independent laboratory that you set out and post yourself.

An average under the guideline calls for no action, although lower is still better, because no radon level is considered free of risk. And if the house came with a system that is already running, treat it as equipment that needs checking from time to time. For homes with an active mitigation system, Health Canada recommends a retest every five years, and a new test after a system is installed or after any renovation that affects the structure or ventilationsource.

Where does radon stand with Alberta's real estate regulator?

It is a topic the province's real estate professionals are expected to recognise. The Real Estate Council of Alberta has issued guidance on radon for its licensees, and it added the subject to re-licensing education in 2019source. Your agent should therefore be able to raise the subject and point you to that guidance.

What it requires of an agent in a particular sale, and what a seller has to disclose, are questions for the agent, the brokerage, the regulator or a lawyer. We stay with measurement and repair. Agents who want the technical background will find it on our radon page for Calgary realtors, and anyone comparing test methods can start from the main radon testing page for Calgary. To see where a number from an existing report falls, use the test result checker or read how the Canadian guideline sorts radon results.