Frozen and burst pipes

The honest answer is that it depends on the season, the property and — critically — what your own insurance policy says. There is no universal standard, and anyone who gives you a single number without asking about your policy is guessing.

That said, the practical logic is straightforward. The damage from most vacant-property failures is proportional to how long they run undetected, so the visit interval is effectively a cap on your worst-case outcome. A leak found after three days and the same leak found after three weeks are very different events.

In practice, weekly is the most common cadence for an Alberta property during the heating season, with owners increasing to twice weekly or every 72 hours during extreme cold. Through summer, weekly or biweekly is common. Properties with known risk factors — poly-B plumbing, an aging hot water tank, a history of basement water, or no water shut-off — warrant more frequent visits than a newer, lower-risk property.

The number that actually matters is the one in your policy. Many policies contain a required check interval during extended absences, and some specify who must perform it. Call your insurer or broker and ask directly before you leave.

For an extended absence in an Alberta winter, shutting off the water is the single most effective step available to you. It removes the mechanism for the most expensive thing that happens to vacant homes.

The reasoning is simple. A supply line that fails while the water is on runs continuously at full pressure until someone closes a valve. The same failure with the water off produces nothing. Shutting off does not prevent pipes from freezing, but it dramatically limits what happens when one does.

For it to work properly, shutting off is not enough on its own — the system should also be drained. Open the lowest fixtures to relieve pressure and let standing water out. Water left in the lines can still freeze and split a pipe; you simply avoid the continuous flow afterwards.

Some caveats. If your property has a fire sprinkler system, do not shut off the supply — that system needs to remain charged. If the property has a boiler or in-floor heating, the heating loop is separate from the domestic supply and needs different handling. If the shut-off valve is old, seized or leaking, force it and you may create the problem you were preventing; have a plumber deal with it first.

Also check your policy. Some insurers require water to be shut off and drained during extended absences in the heating season, and some accept maintained heat as an alternative. Which one applies to you is worth knowing before you decide.

The basic sequence is: close the main shut-off valve, then open fixtures from the highest point in the house downward, letting air in and water out. Open both hot and cold at each fixture. Flush toilets to empty the tanks. Open exterior faucets after closing their interior shut-offs.

A few additions that matter. Drain the washing machine supply lines by closing their valves and disconnecting or running a short cycle. If you are leaving the hot water tank drained, follow the manufacturer's procedure and switch off its power or gas first — an electric element energised in an empty tank fails immediately.

Add a small amount of plumbing antifreeze or mineral oil to traps if you are draining fully, since drained traps lose their seal against sewer gas.

Where this gets beyond a homeowner task: properties with boilers, in-floor heating, water treatment equipment, sprinkler systems or complex mechanical arrangements need a plumber. So does any property where the shut-off valve is old or does not close fully.

For clarity on our side — VacantHomes attendants confirm and document the state of your water and operate an accessible main shut-off per your instructions. Draining systems, servicing valves and any work on a water heater is plumbing work and goes to a licensed plumber.

Water freezes at 0 °C, but pipes inside a building do not freeze the moment the air outside hits that figure. What matters is the temperature at the pipe, which depends on where it runs, how well that space is insulated, how long the cold persists, and whether wind is driving heat out of the assembly.

A pipe in a heated interior wall may be fine at −30 °C outside. A pipe in an uninsulated exterior wall, an unheated garage, or a crawlspace can freeze with the interior at a nominally reasonable temperature, because the pipe is not experiencing the interior temperature.

The commonly cited threshold for concern is a sustained outdoor temperature below about −6 °C, with risk rising sharply as temperature drops and duration extends. Wind matters a great deal — it accelerates heat loss from the building envelope.

The practical approach is to identify the vulnerable locations in your specific property rather than watching a single number: exterior walls with plumbing, unheated garages, basements with poor insulation, rooms above unheated spaces, and anywhere with a history of freezing. Those are the places a visit should check.

The most commonly recommended minimum for an unoccupied home in a Canadian winter is around 15 °C, though recommendations range from about 13 °C to 18 °C. Some insurance policies specify a figure — if yours does, that number governs, not a general recommendation.

The reasoning behind keeping it that high rather than lower: the thermostat reads the air temperature at one location, usually a hallway on the main floor. Temperatures elsewhere in the building — exterior walls, the basement, above the garage, in a bathroom on a corner — run meaningfully colder. Setting 15 °C at the thermostat may mean 8 °C or lower where the plumbing actually is.

Setting it much lower to save on heating is a poor trade. The savings over a winter are modest; the cost of a single burst supply line is not.

A few practical points. Leave interior doors open so heat circulates. Open cabinet doors under sinks on exterior walls. Keep registers open in every room, including ones you would normally close off. If the property has a smart thermostat, set a floor rather than a schedule, and check that any away mode does not drop below your intended minimum.

And ask your insurer whether your policy specifies a minimum temperature during absences. Several do.

Only if the water supply has been shut off and the system properly drained, and even then it is a bigger step than most owners realise.

With water fully drained there is no plumbing left to freeze, so the freeze argument for heating disappears. But an unheated building through an Alberta winter has other consequences: condensation and moisture cycling in the structure, stress on finishes, adhesives and materials from repeated freeze-thaw, and potential problems with anything left in the property.

A property with a boiler or in-floor heating cannot simply be shut down — those systems have their own fluid that needs handling, and shutting down without proper procedure risks damage to the system itself.

Your insurer likely has a view on this. Many policies require either maintained heat or a drained system during heating-season absences, and some are specific about which. Confirm before deciding.

For most owners leaving for a season, maintaining a minimum temperature is the simpler and safer choice. Full shutdown makes sense for genuinely long-term vacancy — an estate property with an uncertain timeline, or a property awaiting redevelopment — and is worth setting up properly with a plumber rather than improvising.

The building starts cooling at a rate determined by its insulation, air sealing, the outdoor temperature and the wind. A well-built modern house in moderate cold may lose only a few degrees a day. An older house during a −30 °C wind event can approach freezing internally within a day or two.

The consequence is not a cold house — it is frozen plumbing. Once interior temperatures at vulnerable locations reach freezing, supply lines begin to freeze, and the failure typically shows itself when the ice thaws and water starts running.

This is why visit frequency during cold events matters more than visit frequency generally. The difference between finding a heating failure after two days and after two weeks is the difference between a service call and a restoration project.

On a monitored property the sequence is: the failure is found on a visit, documented, you are contacted, and a licensed HVAC contractor is dispatched under whatever authorisation you have set in advance. Setting that authorisation before you leave is what allows it to happen at 8 PM on a Sunday rather than after an email exchange across time zones.

Connected temperature sensors can shorten detection further and are a sensible supplement — though they only tell you something is wrong, and somebody still has to go to the property.