Radon for property managers

Which units in a residential portfolio should be tested first?

The ones in contact with the ground, where people live on the lowest level. That means detached and semi-detached rental houses, basement suites, and townhouse-style units with their own basement or slab.

The reason is the route the gas takes. The gas enters through cracks in foundation floors and walls, construction joints, gaps around service pipes, support posts, window casements, floor drains and sumps, and is drawn in because indoor air pressure is usually lower than the pressure in the soilsource. The measurement guide points the same way. Health Canada's guide puts the detector in a regularly occupied room, on the lowest level of the home that is lived insource. A suite whose bedroom sits on the basement slab is, for a manager sorting a list, the first line on it.

Putting ground-contact units first is an ordering, not a cut-off. Testing is recommended by Health Canada for every home, whatever the type of building and wherever it is locatedsource. The honest plan is to begin with the lowest lived-in levels and to show the owner, address by address, which units have not yet been measured.

Why can one unit's result not stand in for another?

Because radon is a property of a particular dwelling and its foundation, not of a street or a building type. Levels vary from one house to another, even between similar houses next door to each other, and the only way to be sure of a home's level is to test itsource.

Sampling is the habit that fact rules out. Managers are used to inspecting a few roofs and budgeting for the rest, and it is natural to want the same economy here. With radon, a low result at one address says nothing reliable about the identical house two doors down, and a high one does not condemn it either. A result in one unit does not describe the unit next to it, even when both share a wall. Where a budget forces a sequence, call it a sequence: these addresses this winter, those the next, with the untested ones named as untested.

What kind of test should each unit get?

A long-term one, with a passive detector read by a laboratory. Health Canada's recommended measurement runs for 3 to 12 months, and 91 days is the minimumsource. It does not recommend testing for periods shorter than 91 dayssource.

That suits rental units better than it first appears. A passive detector is small, silent and has no display, so there is nothing for an occupant to operate. Two types of passive device are recommended by Health Canada for long-term tests, the alpha track detector and the electret ion chamber, and electronic radon monitors are also usedsource. One visit places the device and a second collects it. The laboratory then returns a single average in Bq/m³ for the address. The individual steps are laid out on the page about how a long-term radon test is carried out, and owners who prefer to place devices themselves can compare mail-in radon test kits.

When should a round of tests be scheduled?

Across the heating season, with the detectors out before the cold arrives. At least 91 days of each test should fall in the heating season, when windows are closed and indoor radon tends to be highestsource. The advice attributed to Health Canada in the Canadian mitigation standard is to test for at least three months, ideally between October and Aprilsource.

For a manager this turns radon into a calendar item like any other seasonal task. Placement fits naturally beside autumn furnace servicing, and collection beside spring checks. A unit that changes hands partway through is a planning question, since the detector should stay in the same spot for the whole period. Tell the incoming tenant it is there and why. If a unit will stand empty for much of the winter, raise it before the test starts, because the measurement is meant for rooms people occupy. Our guide to winter radon testing in Calgary goes further into the season.

Where does the detector go inside a unit?

In a room the tenant uses for hours each day, on the lowest level they live on. Health Canada's criteria are a regularly occupied room, used 4 or more hours a day, on the lowest lived-in level, with the device about 30 cm or more from the floor and away from walls, kitchens, bathrooms, laundry rooms, vents, heat sources, direct sun and electronicssource.

In a house rented as one home with an unfinished basement, that is usually a main-floor bedroom or living room. In a house with a basement suite, the suite has its own qualifying room and the upper unit has another. The suite comes first, and a second detector upstairs is optional. Mechanical rooms and shared laundry rooms fail the criteria even though they are easy for a manager to reach. Convenience of access is not a reason to choose a location.

How should tenant notices be handled across many units?

With one standard notice, sent the same way to every unit and logged against the address. The wording a tenant needs is listed item by item on our page on radon in a rented home, and a manager can use that list as it stands.

What a portfolio adds is consistency. Send the same text to each unit, record the day it went out, and keep a copy beside the unit's line in the register. A tenant who moves in halfway through a test receives the same notice on arrival, so nobody finds an unexplained device on a shelf.

Keep the health wording within the federal source. The only known health effect of radon that Health Canada lists is an increased risk of lung cancer, a risk that is long-term and not immediate and that depends on the level, the duration of exposure and smokingsource. A notice can say that Health Canada recommends a test for every home. Local context helps a reader see why the manager is bothering. In the Cross-Canada Survey of Radon Exposure, about 1 in 6 houses in the Calgary area (15.5%) measured at or above 200 Bq/m³, and the area average was 102.5 Bq/m³source.

Ask each tenant to leave the detector where it is, and to tell the office if it is knocked down or goes missing. How entry is arranged is a legal matter for your own process and adviser. We do not describe it. Tenants who want background can be pointed to the guide on radon and health.

How should results be recorded across several properties?

Unit by unit, in one register, with enough detail that a successor could trust each line. A bare number in an email is hard to rely on once the people involved have moved on.

An owner who has never stood in the unit reads the register as the property, so the summary has to be plain. A simple sort does it: units above the guideline, units below it, units not yet tested. Resist averaging the portfolio. An average across addresses hides the one unit that needs work. Anyone can place a single figure with the radon test result checker, and the guide to reading a radon report explains each line of a laboratory sheet.

What happens when a unit comes back above the guideline?

The owner is advised to mitigate, within a period that depends on how high the average is. For indoor air the Canadian radon guideline stands at 200 Bq/m³, with corrective action recommended by Health Canada once the annual average is above itsource. Above 200 Bq/m³, Health Canada recommends mitigating within one year, sooner the higher the level, and bringing levels as low as reasonably achievablesource. Health Canada's guidance is that a radon reduction system can usually be installed in less than a day and that, in most homes, it reduces radon by more than 80%, at a cost comparable to other common home repairssource.

The recommendation to act is tied to averages above the guideline. Where a unit comes in below it, the owner decides what to do; no level is considered risk-free, and a lower one is better. The page on Canadian radon guidelines sets out the ranges in full.

A manager's task at this stage is mostly coordination: pass the report to the owner, arrange access for an assessment, and tell the tenant what was found and what comes next. Who pays, and what a lease or the law requires, are questions for the owner and their legal adviser. On the technical side, the usual arrangement keeps the fan on the pipe in the basement, with the exhaust through the rim joist to the side of the building, or above the roof by an inside route where the layout requires it. The design is explained on our page on radon mitigation systems in Calgary, and budgeting is covered in the mitigation cost guide.

How is a system looked after once it is in?

With a glance at the gauge during routine visits and a retest on the interval Health Canada gives. A mitigation system is equipment, and a rental unit can change occupants several times over its life.

The U-tube manometer on a system's pipe indicates that it is working, a higher liquid level on one side being the sign of the pressure difference created by the fansource. That makes it an easy line on a move-in or move-out checklist. Level columns are a reason to call for an evaluation, not a diagnosis. The lifespan of a radon fan can vary between five and ten or more years, according to Health Canada's Radon Reduction Guide for Canadians (2014)source, so a replacement belongs somewhere in a long-range maintenance plan. See radon fan replacement in Calgary for what that involves.

When a unit has been mitigated, expect a short verification reading from the installer after the system has been started. The lasting confirmation is a long-term kit analysed by an independent laboratory, which the owner, and not the installer, places and mails. For homes with active mitigation systems, Health Canada recommends a retest every 5 years, and a fresh test after a system is installed or after any renovation affecting the home's structure or ventilationsource. Put that date in the register beside the unit.

What can we do for a portfolio, and what falls outside our work?

Our work is residential: rental houses, suites and units in multi-unit residential buildings. We do not currently take on offices, shops, schools, daycares or other non-residential buildings, and we would sooner say so here than after a site visit.

Within that scope, the person matters more than the company name. Health Canada recommends that owners hire a professional certified through the Canadian National Radon Proficiency Programsource. C-NRPP runs a public search tool for certified professionals and a certification check that confirms an individual's certification from the certification numbersource. Testing and mitigation here are carried out by Plinio Neto, who holds the C-NRPP Radon Measurement Professional certification (CRT-202965) and the C-NRPP Radon Mitigation Professional certification (CRMT-202966). An owner can confirm both in the C-NRPP register of certified individuals before any work is approved.

We have published nothing on how visits to many addresses are scheduled, on the format of a combined report or on pricing for a group of units, so none of those is promised here. Send the list of addresses through the form on this page, or write to us from the contact page, and ask. The reply will say which parts of the list we can take on.