Winterize a Canadian home in the order that matters: find and seal air leaks, check insulation, service the heating system, and protect water pipes from freezing, using Natural Resources Canada's Keeping the Heat In guidance and Toronto's frozen-pipe steps as the worked example.
Applies in: across Canada
Winterizing a home means getting the building ready for months of cold, in the order that prevents damage rather than the order that feels satisfying. The sequence in this guide follows Natural Resources Canada's Keeping the Heat In: understand how the house works as one system, control air leakage, check insulation, then operate the heating system and watch moisture and ventilation. Water pipes get their own step, using the City of Toronto's frozen-pipe guidance as the worked example, with the general rules stated so they apply outside Toronto too. This guide names no product, recommends no contractor, and states no price. If you rent, check the lease and the landlord before doing work that changes the building.
A house is a building envelope, a mechanical system, and the people living in it, working together. The envelope is the shell: the foundation walls and floor, the above-grade walls, the roof, and the windows and doors. It must control the flow of heat, air, and moisture from inside to outside. Change one flow and the others move with it. Sealing air leaks changes humidity and the air available for combustion appliances. Adding insulation changes how the heating system should be sized and run. That is why Natural Resources Canada presents the house-as-a-system principle before any retrofit step, and why an EnerGuide evaluation is useful before major work: it identifies the areas of the house with room for improvement, from low-cost air sealing up to a major renovation.
Start with a walk-through on a cold, windy day. Note the rooms that feel cold near windows and outside walls, the windows that show condensation, the doors that rattle, and the basement and attic spaces that feel colder than the rest of the house. Write the list down. Work through it in the order below, and check the moisture and ventilation signs in Step 6 after the sealing work is done.
Air leakage control is the systematic identification and sealing of leaks, using weatherstripping and caulking and by applying gaskets and tapes. That is how Keeping the Heat In, Chapter 4, defines the work. Air leaks occur where there is a hole in the building envelope: around windows and doors, at electrical outlets and light fixtures, where pipes and wiring pass through walls and floors, at the attic hatch, and where the foundation meets the framing. Natural Resources Canada states that typically about 25 percent of heat loss can be due to excess air infiltration, which is why sealing is placed before insulation in the sequence.
Find the leaks before sealing them. On a windy day, hold a hand near window and door edges, outlets on outside walls, and pipe entries, and feel for moving air. A contractor can locate leaks with a depressurizing fan door, known as a blower door test, and an infrared scanner used with the blower door test is also a powerful tool for finding them. Many air sealing companies also offer testing and assessment of ventilation and combustion air requirements, including testing for backdrafting. That assessment matters where a furnace, water heater, fireplace, wood stove, or other fuel-burning appliance is present: those appliances require air for combustion and for exhausting the products of combustion, and if there is not enough air, the chimney or flue could spill dangerous gases into the house. Do not seal the air supply to a fuel-burning appliance. If the house has a natural-draft or atmospherically vented appliance, get advice before extensive sealing work.
Seal with the right material for each gap: caulking for fixed cracks, weatherstripping for moving parts such as doors and opening windows, and gaskets and tapes for hatches, outlets, and barrier seams. Force caulk into the crack rather than laying it across the surface, and cut the nozzle squarely. Work from the attic down and the basement up, since the house tends to operate like a chimney, with warm air rising and drawing cold air in low down. Re-check the seals after the first cold spell, when materials contract and gaps open.
Insulation slows heat flow through the envelope. Keeping the Heat In covers roofs and attics, basement insulation, insulating walls, and upgrading windows and doors as separate chapters, because each part of the envelope is checked differently. In the attic, check the depth and coverage of insulation, look for gaps around the hatch and around pipes and wiring that pass through the ceiling, and check that vents are not blocked by insulation. In the basement, check the walls and the rim area where the framing meets the foundation. In the walls, check for cold spots and draughts that suggest missing or settled insulation, and remember that opening a wall to add insulation is a bigger job than sealing, so it belongs after the sealing work, not before it.
Install at least the minimum insulation levels according to local building codes, and exceed those values where it is practical and economical. That is the guidance in Chapter 2, which also publishes guideline insulation levels by heating degree-day zone. This guide states no insulation thickness or R-value for any part of the house, because the right level depends on the climate zone and the local code version in force where the house stands. Check the code and the zone for the house, and check the product data for the insulation being installed.
For windows and doors, check the seals first, since a failed seal loses more heat than a sound window of an older type. Check weatherstripping, the seal between glass and frame, and the fit of the door in its frame. Hinged windows and doors seal more tightly than sliders, because they use compression seals. If a window or door is being replaced, check its energy-performance rating and its air-leakage rating, and confirm how the installation will seal the opening against drafts. Keep furniture and curtains clear of heating vents and radiators so warm air can circulate, and do not cover a heater with curtains.
Have the heating system checked before winter, and follow the manufacturer's maintenance schedule for the equipment in the house. Keeping the Heat In, Chapter 9, covers operating and maintaining the heating, ventilating, and air-conditioning system as its first section, including domestic hot water, ventilation, and combustion air. The homeowner checks are the ones the manufacturer lists for the model: filters, vents, and controls, kept to the schedule in the manual. Book the check in the fall, before the first sustained cold spell, when service schedules fill.
For a furnace or boiler, the check confirms that the system starts, runs, and shuts off as the controls require, and that combustion air and venting are clear. For a heat pump, the check confirms the outdoor unit is clear of leaves and snow, the filters and coils are clean to the manufacturer's schedule, and the supplemental heat switches in when it should. Natural Resources Canada states that air-source heat pumps are the most common type in Canada, that supplemental heating may be required when outdoor temperatures are between minus 10 and minus 15 degrees Celsius, and that cold-climate air-source heat pumps can operate down to minus 30 degrees Celsius. Air-source systems are up to 2.5 times more efficient than an oil furnace or boiler, and cold-climate systems can reach efficiencies up to 3 times higher. Sizing and installation decide whether those figures are reached in a particular house: undersizing or oversizing can make the system more costly and less efficient, and the design should account for other planned envelope upgrades so the unit is not oversized for the improved house.
Use the thermostat as part of the system, not as an afterthought. A drop of 1 degree Celsius over an eight-hour period can save about 2 percent on heating energy, as Chapter 9 states it. Set a steady temperature overnight and while away rather than swinging the setting up and down, keep the house warm enough that pipes and exterior walls stay above freezing, and insulate hot water lines: Chapter 9 specifies insulating both metallic and plastic water lines with a minimum of RSI 0.7 (R-4) compatible insulation. For the full heating-system steps, read the heating guides on this site: the heat pump guide for sizing, installation, and operation, the heating and electricity bills guide for the bill side of the same work, and the furnace replacement cost guide where replacement, rather than a check, is the question.
Water pipes freeze where cold air reaches them: against exterior walls, where the water service pipe enters through the foundation wall, and in crawl spaces, attics, and garages. The City of Toronto's frozen-pipe guidance is used here as the worked example because it states each step as a municipal instruction with a temperature trigger. The general rules travel to other municipalities; the reporting route does not. Check your own municipality's frozen-pipe page for its reporting number and its trigger temperature.
Toronto urges precautions when forecasted nighttime temperatures drop below minus 10 degrees Celsius. Its tips, in its order, are: know where the main water shut-off valve is and how it works, in case pipes burst, and keep areas containing indoor water pipes above 8 degrees Celsius, especially near the water meter; keep garage doors closed if water supply lines run through the garage; disconnect hoses from outdoor faucets, turn off the outdoor water supply, and let the taps drain, since outdoor faucets are the first to freeze; insulate pipes most prone to freezing, especially near outside walls and in crawl spaces, the attic, and garage, using foam pipe covers; seal air leaks in the home and garage to stop cold air getting in, checking around windows and doors, electrical wiring, dryer vents, and pipes; raise the temperature in the home by one or two degrees, especially at night; open kitchen, bathroom, and laundry cabinet doors to let warm air circulate around plumbing; and, as a precautionary measure, run a pencil-thin stream of water in pipes that might be vulnerable, leaving it flowing 24 hours a day until daytime and nighttime temperatures have returned to normal seasonal averages, keeping the drain clear of debris to prevent overflowing or flooding.
If you turn on the taps and have no water, the pipes may be frozen. Apply heat to the suspected frozen pipe by warming the air around it or applying heat directly to it, using an electric heating pad, hair dryer, space heater, or warm towel or rag. Do not leave electrical devices unattended, and do not use kerosene or propane heaters, charcoal stoves, or any open flame to thaw a frozen pipe. Depending on the outside temperature and the extent of freezing, thawing can take between one and six hours. Once the pipes have thawed, turn the water back on slowly and check for cracks and leaks, and turn on a tap in the basement, preferably the cold-water faucet in the laundry room. In Toronto, if the steps do not resolve the issue, call 311 or submit a service request online and the City will investigate. In another municipality, use that municipality's reporting route, and contact a plumber for advice where the guidance says to, particularly if the pipes inside the home are prone to freezing.
After sealing and insulating, watch the house for two weeks. Signs of higher relative humidity include condensation on windows, stale air, and lingering odours. Those are the signs Chapter 2 names for a house whose moisture balance has shifted. If they appear, adjust the heating system and house ventilation to keep the system working properly, and get advice if the signs persist. Do not respond by opening sealed gaps at random, and do not seal further until the ventilation and combustion-air position is clear.
Keep the exterior water-shedding parts in the same maintenance round: flashing, gutters, and other construction techniques that shed water away from the walls and foundation, with grade slope and drainage that keep groundwater away from the foundation. Those are the exterior strategies Chapter 2 lists for keeping the structure dry. Clear gutters and downspouts of leaves before snow, check that downspouts carry water away from the foundation, and check the roof for damaged or missing covering before the first heavy snow. If the house shows signs of a roof leak, foundation damp, or mould, stop and get advice on that problem before adding insulation over it, since insulation over a wet structure traps the moisture it was meant to keep out.
A final check before the first cold snap: walk the house once more with the list from Step 1. Every item on it should now have a result: sealed, insulated, checked, or booked with a date. Anything still open goes on the list for the next mild spell, with the pipe steps in Step 5 treated as the priority if cold arrives first.
The steps that do not change the building belong to the tenant: thermostat settings, opening cabinet doors so warm air reaches plumbing, keeping garage doors closed where supply lines run through the garage, reporting drafts and pipe risks, and knowing where the main water shut-off valve is. Sealing, insulation, and heating-system work change the building and need the owner's agreement, so check the lease and ask the landlord before doing them. If a pipe freezes or bursts in a rental, shut off the water if you can do so safely, tell the landlord at once, and follow the municipality's frozen-pipe steps for the thawing and reporting part.
Natural Resources Canada states the caution plainly in Keeping the Heat In. Fuel-burning appliances need air for combustion and for exhausting the products of combustion, and a house that is sealed without enough air can spill dangerous gases back through a chimney or flue. The same guidance states the reassurance: most older houses are so loosely built that even extensive air-leakage work leaves enough air coming in to ventilate them. The working rule is to seal the leaks, keep combustion air, and watch for condensation on windows, stale air, and lingering odours after the work. If those signs appear, adjust the heating and ventilation and get advice rather than sealing more.
Natural Resources Canada states the figure in Keeping the Heat In, Chapter 9: a drop of 1 degree Celsius over an eight-hour period can save about 2 percent on heating energy. That is a guide figure for a setback held for eight hours, not a promise for a particular house or a particular week. Set the setback on a programmable or smart thermostat if the house has one, keep the temperature steady enough that pipes and walls stay warm, and check the result on the next heating bill rather than assuming the saving.
Do not turn the heat off. The City of Toronto's frozen-pipe guidance states that areas containing indoor water pipes should be kept above 8 degrees Celsius, especially near the water meter, and its tips include raising the temperature by one or two degrees at night. Before leaving, disconnect outdoor hoses, shut off and drain the outdoor water supply, close garage doors where supply lines run through the garage, and confirm that someone can check the house and the heating system while you are away. Know where the main water shut-off valve is before you leave, so a burst pipe can be stopped quickly.
Natural Resources Canada states that air-source heat pumps draw heat from outside air to warm a home and expel heat to cool it, that supplemental heating may be required when outdoor temperatures are between minus 10 and minus 15 degrees Celsius, and that cold-climate air-source heat pumps can operate when outdoor air temperatures are as cold as minus 30 degrees Celsius. Proper selection, sizing, and installation matter: undersizing or oversizing can make the system more costly and less efficient. Have the system checked before winter, follow the manufacturer's maintenance schedule, and read the heat pump guide on this site for the sizing and installation steps.
Start in the fall, before sustained cold arrives, and work from the outside in: roof and gutters, then the envelope, then the heating system, then the pipes. Air sealing and insulation work is easier and safer in dry weather, heating checks need a booking before the first cold snap fills schedules, and outdoor water must be shut off and drained before the first freeze. If the first freeze arrives before the work is done, do the pipe steps first, in the order Toronto's guidance lists them, and carry the envelope work into the next mild spell.
No insulation thickness, R-value, product, contractor, price, rebate amount, or filter-change interval is stated in this guide, because none could be verified on the Natural Resources Canada pages beyond the RSI 0.7 water-line specification stated above. No roof, gutter, or ice-dam technique beyond the general exterior water-shedding strategies is stated. The Canada Greener Homes Affordability Program and any income-qualified winterproofing program are not described in detail here; check the current program pages for eligibility and for the provincial or territorial partner that delivers them where you live. Re-check your municipality's frozen-pipe page for its trigger temperature and reporting route, since Toronto's figures govern Toronto only.