Every Canadian property manager eventually gets the 6 a.m. call: no water in unit 3, and by noon the ceiling in unit 2 is on the floor. Learning to prevent frozen pipes in a rental property is less a plumbing skill than a scheduling one, because almost every burst line traces back to something that should have been done in October and was not. The mechanics are simple. An ice plug forms in a cold run, pressure builds between that plug and a closed tap, and the pipe splits somewhere you cannot see. Nothing leaks while it is frozen. The flood arrives with the thaw, often while nobody is home. This guide covers where freeze-ups really happen in Canadian housing stock, the pre-winter checks that matter, the insurance clause that quietly decides who pays, and what to do in the first twenty minutes.
Where Pipes Actually Freeze in Canadian Rentals
Freeze-ups are rarely about how cold it got. They are about where cold air reaches a still column of water. In older wood-frame stock across Ontario, the Prairies and Atlantic Canada, the same handful of spots account for most claims:
- Supply lines inside exterior walls, classically the kitchen sink on the north or west wall of a pre-1960 house.
- Vented crawl spaces under additions and back kitchens, where batt insulation has sagged off the joists.
- Rim joist penetrations near an outdoor hose bibb, where a finger-width gap lets minus 25 air blow straight onto copper.
- Attic and knee wall runs in 1.5 storey homes, especially where a bathroom was added later.
- Unheated garages and mud rooms with a laundry hookup or utility sink.
- Basement suites on a separate thermostat, where the tenant pays the bill and keeps it low.
- Any vacant unit, and above all a unit turned over mid-winter.
Air sealing beats insulation here. Pipe wrap slows heat loss from the pipe, but it will not save a line with outdoor air blowing across it. Seal the hole first, then insulate.
How to Prevent Frozen Pipes in a Rental Property Before the First Freeze
Book the walkthrough for early October, before the trades get slammed and before the first cold snap does the inspecting for you. Work the building in this order:
- Drain every exterior hose bibb. Close the interior stop valve, open the outside spigot, and leave it open all winter. Pull the garden hoses off, because a hose left connected to a frost-free bibb traps water in the barrel and defeats the design entirely.
- Seal, then insulate. Foam or caulk every point where plumbing passes through a rim joist, sill plate or exterior wall, then add pipe insulation on runs in unheated space.
- Heat trace what you cannot move. For a line stuck in a crawl space or wall cavity, a CSA certified self-regulating heating cable on its own thermostat is the practical fix, installed to a dedicated protected outlet rather than an extension cord.
- Service the heating plant before you need it. Furnace, boiler or electric baseboards, book the licensed technician in September. A no-heat call during a minus 30 week can mean a two-day wait, and two days is plenty.
- Run every zone up to temperature. Confirm each room actually heats, including the ones nobody uses. A dead baseboard in a spare bedroom on an exterior wall is a freeze-up waiting for its night.
- Find, label and test the shut-offs: main valve, unit valves, laundry box and water heater isolators. Photograph them for the tenant welcome sheet.
- Fix the envelope. Crawl space vents, a basement window that no longer latches, a garage service door that will not close in the cold.
- Add sensors. Wi-Fi leak detectors under sinks and at the laundry box, plus a low-temperature alert on the thermostat, will flag trouble hours before a tenant does. On vacant units this is close to mandatory.
- Clear the drainage side. Blow out irrigation and make sure sump discharge lines are not buried in ice.
- Book a plumber for anything you could not assess yourself.
Turn that list into a dated, photographed checklist per building, because it is exactly what your insurer and your provincial tenancy board will ask to see. Our Canadian property manager hub covers building repeatable seasonal routines across a portfolio.
Heat, Vacancy and the Clause That Decides Who Pays
This is the part most owners discover after the loss. Property policies in Canada commonly exclude water damage caused by freezing while a building is vacant or unoccupied, unless the insured either maintained heat or shut off the water supply and drained the system. Many wordings also require the property be checked at a stated interval by a competent person. Pull your policy, or ask your broker to send you the freezing and vacancy clauses in writing, and diarize whatever interval it names.
That leaves two acceptable states for an empty unit: heated and monitored, or shut off and properly drained. Efforts to prevent frozen pipes in a rental property collapse the moment someone turns the thermostat down to save on gas during a January turnover, which is the single most expensive habit in this business.
- Never let a unit sit below roughly 15 °C, and keep it warmer where supply lines run through exterior walls.
- Know your municipality's property standards bylaw. Most Canadian cities set a minimum indoor temperature and fixed heating season dates. Those are your legal floor, not your risk floor.
- During a documented cold snap, check vacant units in person and keep the dated photos.
What to Ask of Tenants, and How to Ask It
You cannot prevent frozen pipes in a rental property from the office, and where the tenant pays for heat you are managing an incentive problem. A short, friendly notice in November lands far better than a clause nobody read at signing:
- Keep the thermostat at the agreed minimum, even when away.
- On extreme cold nights, open the cabinet doors under sinks on exterior walls so room air reaches the pipes.
- Leave a trickle running from the tap furthest from the main on the coldest nights. Moving water is much harder to freeze.
- Do not close registers or block baseboard heaters with furniture or boxes.
- Report any loss of heat the same day, not the next business day.
- Tell us before leaving the unit empty for more than a couple of days.
- Know where your shut-off valve is, and keep the emergency number handy.
Provincial residential tenancy legislation puts the repair and maintenance duty on the landlord and a duty not to cause negligent damage on the tenant. Whether a given freeze-up counts as negligence is decided case by case, so your written notice and dated inspection records matter more than the lease wording.
The First Twenty Minutes of a Freeze-Up
When a tenant reports no water on a cold morning, assume a frozen line and act in this order:
- Shut off the main, or the closest isolation valve upstream.
- Open the affected tap so meltwater and pressure have somewhere to go.
- Apply gentle heat at the suspected spot with a hair dryer, heating pad or space heater at a safe distance, working from the tap back toward the ice. Never use a torch or open flame.
- Inspect the full run for a split before restoring pressure, and bring the water back slowly with someone watching the pipe.
- If it has already burst, kill power to circuits near standing water at the panel, then start extraction and drying the same day. Mould does not wait for the adjuster.
- Call a licensed plumber and document everything with timestamped photos.
Put It on the Calendar, Not in Your Head
Two dates prevent nearly all of this: an early October inspection and a mid-January check on vacant units and unheated spaces. The hard part in most Canadian markets is finding trades who will show up in the shoulder season. Platforms like PlanaJob let property managers post the job once and compare quotes from vetted contractors instead of phoning down a list, and PlanaJob plumbers offer pre-winter inspections that cost less than the deductible on a single burst-pipe claim. You can set up an account in a few minutes and have the October walkthrough quoted before the calendar fills. More seasonal maintenance guides are on the PlanaJob blog.
Contractors reading this: a signed pre-winter inspection package smooths winter cash flow and buys you first call when the emergency comes, an argument made well over at Construction Arbitrage.
FAQ
At what outdoor temperature do pipes start to freeze?
The number that matters is the temperature at the pipe, not on the forecast. A well-sealed interior line can ride out an extreme cold warning without trouble, while a poorly sealed crawl space run can plug on the first sustained night below about minus 10 with wind behind it. Treat the first hard freeze and any multi-day cold snap as your trigger points, and watch wind direction, since exposed north and west walls go first.
Who pays for a burst pipe, the landlord or the tenant?
Repairs to the building sit with the landlord under provincial tenancy legislation, and the tenant's belongings are covered by their own contents insurance, which is why requiring tenant insurance is worth doing. Costs can shift toward the tenant where damage follows negligence, such as shutting off the heat or leaving a window open in January. That is a case-by-case determination at the tenancy board, and it turns entirely on documentation.
Should I leave the heat on in a vacant rental all winter?
Yes, or shut off the water and drain the system properly. Those are the two states most Canadian policies accept. A unit left at a token temperature with live plumbing and nobody checking it is the combination that produces a denied claim. If you keep the heat on, use a thermostat that alerts you when the temperature drops, and inspect on the schedule your policy names.