Winterizing Your Home

Why it matters here

Lethbridge winters aren’t the snowiest in Canada, but they’re hard on a house in their own way. January nights average a low of about −12°C, and arctic air can push well below that for days at a time. Then a chinook arrives, the snow melts, and everything freezes again overnight. Add our wind, which drives cold air through every gap and piles snow against the walls, and small problems show up fast.

Most of the work is simple. The yard jobs (hoses, outdoor taps, irrigation, leaves and tools) are on our spring and fall yard checklists. This page is about the house itself. If the power goes out in a cold snap, our power outages page takes over.

The furnace, its filter and its vents

The filter

Canada Mortgage and Housing Corporation’s (CMHC) home maintenance schedule says to check and clean or replace furnace air filters each month during the heating season. Write the date on the edge of each new filter. If you have a heat recovery ventilator (HRV), CMHC suggests checking its filters every two months.

Servicing

• Have fuel-burning appliances inspected. Health Canada says to have a professional inspect your furnace, chimney and vents at least once a year, or as the manufacturer recommends, to help prevent carbon monoxide problems.
• How often to service. Natural Resources Canada says natural gas and propane furnaces should be serviced at least every two years, and oil furnaces cleaned and tuned every year. CMHC’s schedule gives the same timing, or the manufacturer’s.
• Before the first cold night, CMHC suggests checking the chimney for obstructions before you turn on the furnace. If you burn wood, Health Canada says to have the chimney cleaned every year.

Keep the outside vents clear

High-efficiency furnaces and many water heaters vent through a side wall, often close to the ground. In a ground blizzard, those pipes can drift over in an hour.

• Health Canada says to inspect exhaust vents during and after snowstorms, to make sure they aren’t blocked with ice or covered by snow or debris.
• CMHC’s winter list adds keeping snow clear of gas meters, gas appliance vents, exhaust vents and basement windows.
• Use a broom near vent pipes and the gas meter, not a metal shovel, and don’t pile snow against that wall.

Smoke and carbon monoxide alarms

Winter is when the furnace, fireplace and space heaters run the most, so it’s the season your alarms matter most. Lethbridge Fire and Emergency Services gives this advice:

An easy habit: check every alarm when the clocks change in the spring and fall. Lethbridge Fire and Emergency Services also takes requests for free smoke alarm checks through its safety education and fire prevention page, although crews may not be able to visit every home. It’s worth asking for an older relative or neighbour who can’t reach a ceiling safely.

Keeping pipes from freezing

Water expands when it freezes, and a split pipe can flood a basement once it thaws. The pipes most at risk run along outside walls, through crawl spaces and garages, or under sinks on outside walls.

Before the cold

• Find your main water shut-off and make sure everyone in the house knows where it is. If a pipe bursts, turning it off quickly matters most.
• Insulate exposed pipes near outside walls or doors, as St. Albert suggests.
• Look for cold drafts near pipes in basements, crawl spaces, garages and under sinks, as the City of Calgary suggests.
• Outdoor taps: shut off, disconnect and drain them before freeze-up. A hose left on a frost-free tap traps water and can split it inside the wall. The step-by-step is on our hoses and outdoor taps page.

In a cold snap

• Open the cupboard doors under sinks on outside walls, and interior doors to cold rooms. The City of Calgary says this lets heat from the house warm unprotected pipes. Move cleaning products out of children’s and pets’ reach while the doors are open.
• Run a trickle of water if pipes can’t be kept above freezing, as Get Prepared suggests.
• Keep the heat up, even when you’re away. The City of Calgary suggests at least 15°C, and having someone check on the house.

If a pipe freezes

1. Turn off the water at the main shut-off if you think a pipe has frozen, as St. Albert advises, in case it has split.
2. Open the nearest tap and warm the pipe from the tap back toward the frozen spot. The City of Calgary says this reduces the chance of a burst.
3. Use gentle heat: a hair dryer, a heating pad or warm towels. Be patient.
4. Never use an open flame. Both cities say so. Calgary also says never to leave a heat source unattended, and not to work in a cramped space.
5. Call a plumber if you can’t find the frozen spot or it won’t thaw.

Once it’s thawed, Get Prepared says to check for water damage, including leaks behind walls, and watch the area for mould.

Quick wins for drafts

Natural Resources Canada’s guide Keeping the Heat In says uncontrolled air leakage can be a major source of heat loss in a house. Three inexpensive materials deal with most of it:

NRCan’s checklist of places to look includes the attic hatch, where plumbing stacks enter the attic, outlets and switches, baseboards and trim, and door thresholds. On a cold, windy day, a damp hand moved slowly around these spots will find most leaks.

Eavestroughs before freeze-up

CMHC’s fall list says to clean leaves from the eavestroughs and roof, and test the downspouts to make sure water drains away from the roof. Water that can’t get away overflows, runs down the wall and freezes on walks and steps.

• Point every downspout away from the house and away from sidewalks and driveways. A downspout that empties across a walk makes a sheet of ice every night after a chinook, as our sidewalks and snow page explains.
• Through the winter, CMHC suggests checking the roof edge for ice dams and large icicles. Do it from the ground. If you see ice dams, or frost or staining under the roof in the attic, CMHC points owners to its guidance on attic venting, attic moisture and ice dams. Have a roofer or home inspector take a look.
• Icicles over doors and walks can fall. Keep people out from under them.

Snow on the roof

Heavy roof loads are less common here than in snowier parts of Canada. Only about a quarter of our yearly precipitation falls as snow, and chinooks often melt it. The times to pay attention are after a heavy, wet spring snowstorm, and where wind piles deep drifts onto a lower roof behind a taller part of the house.

The City of Saskatoon’s building standards guide for owners lists signs that a roof may be overloaded:

• unusual sounds from the roof or the walls holding it up;
• walls that move or ceilings that sag;
• doors that stop working properly;
• new cracks in drywall or plaster.

If you see any of these, get everyone out of that part of the house and call a professional.

Before the winter storms arrive, Get Prepared suggests checking your house, including the roof, for damage. Look from the ground, or have a professional check it.

Space heaters, safely

A portable electric heater can take the chill off a cold room. Lethbridge Fire and Emergency Services warns that heating equipment can cause fires when it’s used incorrectly. Its advice and the City of Edmonton’s fire safety advice agree on the basics:

• Keep it 1 metre from anything that can burn, and keep children and pets the same distance away, as Edmonton suggests.
• Turn it off when you go to bed or leave home. Edmonton says to turn it off and unplug it whenever you leave the room.
• Plug it straight into a wall outlet. Edmonton says never to use an extension cord.
• Choose one with an automatic shut-off that turns it off if it tips over, and set it on a solid, flat surface.
• Don’t dry clothing on it, and keep it away from water, such as in bathrooms.

Printable checklist

In the fall, before freeze-up

• ☐ Furnace serviced (gas or propane at least every two years; oil every year; or as the manufacturer says)
• ☐ New furnace filter, dated; HRV filters checked
• ☐ Chimney checked for obstructions; wood-burning chimney cleaned
• ☐ Smoke and CO alarms tested, batteries changed, expiry dates checked
• ☐ Main water shut-off found and labelled
• ☐ Hoses disconnected, outdoor taps drained (see hoses and outdoor taps)
• ☐ Exposed pipes near outside walls insulated
• ☐ Weatherstripping and door sweeps checked; gaps caulked; outlet gaskets on outside walls
• ☐ Eavestroughs cleaned, downspouts pointed away from the house and walks (hire out the ladder work if in doubt)

All winter

• ☐ Furnace filter checked every month
• ☐ Outside furnace, water heater and dryer vents and the gas meter cleared after every snowfall or blizzard
• ☐ Cupboard doors open under sinks on outside walls during cold snaps
• ☐ Roof edge and icicles checked from the ground
• ☐ Space heaters 1 metre from anything that can burn, and off at bedtime
• ☐ Older neighbours and relatives checked on during cold snaps (see winter health)

The yard jobs are on our spring and fall yard checklists.

Sources

• Canada Mortgage and Housing Corporation, About Your House: Home Maintenance Schedule (filters, servicing, vents, eavestroughs, ice dams): assets.cmhc-schl.gc.ca
• Natural Resources Canada, ENERGY STAR new homes, Maintenance (furnace servicing): natural-resources.canada.ca
• Natural Resources Canada, Keeping the Heat In (2017): natural-resources.canada.ca
• Health Canada, Carbon monoxide: preventing exposure: canada.ca
• Public Safety Canada, Winter storms: how to prepare: canada.ca
• Public Safety Canada, Extreme cold: how to prepare: canada.ca
• City of Lethbridge, Safety education and fire prevention (alarms; portable heaters): lethbridge.ca
• City of Lethbridge, Check your smoke and carbon monoxide alarms as clocks spring forward: lethbridge.ca
• My Lethbridge Now, Lethbridge’s chief fire marshal offers tips to safely stay warm during cold snaps (February 2025): mylethbridgenow.com
• City of Calgary, Frozen water lines: calgary.ca
• City of St. Albert, Frozen pipes: stalbert.ca
• City of Saskatoon, Building Standards, Snow on roofs: what owners should know: saskatoon.ca
• City of Edmonton, Home heating safety (space heaters): edmonton.ca
• Environment and Climate Change Canada, Canadian Climate Normals 1991–2020, Lethbridge (January mean low; share of precipitation as snow).