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Why Pipes Freeze in Canadian Homes
Pipes freeze when cold air reaches them faster than the house can keep them warm. Exterior walls with gaps in insulation, crawl spaces, unheated garages, cottages and additions built over open foundations are the usual trouble spots. Wind makes it worse, because air leaks can chill a pipe far below the indoor temperature.
Water expands as it freezes. That pressure builds between the ice plug and the closed tap, which is why pipes often split away from the frozen section itself. The leak only shows once the ice melts.
How to Thaw a Frozen Pipe Safely
Start by opening the tap nearest the frozen section. Warm the pipe slowly, beginning close to the tap and working back toward the cold spot so meltwater has somewhere to go. A hair dryer, a heating pad or towels soaked in hot water all work. Raising the heat in the house and opening cabinet doors under sinks helps too.
Keep going until full water pressure returns, then check the pipe and surrounding area for drips. If the frozen section is inside a wall, under a floor or in a crawl space you can't safely reach, it's time for a plumber, who may use specialised thawing equipment.
- Never use a torch, open flame or propane heater
- Don't leave space heaters unattended near pipes
- Don't use electrical tools while standing in water
- Keep the tap open the whole time you're thawing
If the Pipe Has Already Burst
Close the main shut-off immediately. Open the lowest taps in the house to drain the remaining water, and switch off the water heater's energy source if the house has lost most of its water. Move belongings out of the way and start removing standing water, then photograph the damage before you clean too much.
A plumber will replace the split section and check nearby pipes, since freezing often damages more than one spot. Ask them to point out why it froze so you can fix the insulation or air leak afterwards.
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Post my jobFrozen Drains and Water Service Lines
Sometimes it's not a supply pipe that's frozen. Drain lines and plumbing vents on the roof can ice up, causing slow drains, gurgling and sewer smells. In rural homes and cottages, the line from a well or the municipal service line can freeze underground, especially during long cold spells with little snow cover.
If you suspect the service line is frozen, contact your municipality as well. Some cities ask residents in known trouble areas to run a tap at a pencil-thin stream during extreme cold, so check your local water utility's advice.
What a Plumber Will Do
Expect the plumber to locate the frozen section, thaw it with safe equipment, and check for splits or weakened joints. If the pipe has burst, they'll cut out and replace the damaged piece. Ask about rerouting or insulating pipes that freeze often, and about heat cable for runs that can't be moved.
As with any urgent call, ask for the price before work starts, including any after-hours rate.
Stopping Pipes From Freezing Again
Seal air leaks near pipes, insulate pipes in garages, crawl spaces and attics, and disconnect garden hoses before winter. Shut and drain outdoor taps unless they're frost-free. During extreme cold, open cabinet doors under sinks on outside walls and keep the thermostat steady overnight.
If you're leaving home or closing a cottage for the season, keep the heat on or have the plumbing drained and winterized. A frozen pipe in an empty house can run for days before anyone notices.
What Affects the Cost of an Urgent Call
Every job is different, so we don't publish a flat emergency price. Ask for the total before work starts. These are the things that usually move the number:
- Where the frozen or burst section is and how easy it is to reach
- Whether drywall or flooring must be opened
- Thawing equipment needed for buried or enclosed lines
- Pipe material and length to be replaced
- Time of the call: after-hours rates are common
- Travel to rural properties and cottages
For typical price ranges on planned work, see our plumbing cost guide.