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How to winterize your home

Knowing how to winterize your home is what stands between you and the two most expensive cold-weather failures: a pipe that freezes and bursts, and a furnace that quits on the coldest night of the year. The good news is that most of the work is cheap, quick, and one-time. This step-by-step winter maintenance checklist walks through everything — plumbing, heating, the building envelope, the roof, the yard, and a basic emergency plan — roughly in the order that matters most.

Protect the plumbing

Frozen pipes are the single most damaging winter problem for a home, because a small split can flood rooms once the water thaws and starts flowing again. Handle the water first.

• Drain and shut off outdoor faucets. Close the interior shutoff valve for each exterior spigot, then open the spigot outside to drain the line. Water left in an exterior pipe can freeze, expand, and split it — often unnoticed until spring.
• Disconnect and store garden hoses. A hose left attached traps water against the faucet and can freeze the line back into the wall.
• Insulate exposed and crawlspace pipes. Use foam pipe sleeves on any pipe running through a garage, crawlspace, attic, or exterior wall — the coldest, most vulnerable spots.
• Know where your main shutoff is. If a pipe does freeze or burst, being able to kill the water instantly limits the damage. Make sure everyone in the house knows where the valve is and how it turns.
• Keep the house above about 55°F (13°C) when away. Never turn the heat fully off in winter; pipes inside walls and floors need the ambient warmth to stay above freezing.
• Let a faucet drip in extreme cold. During a hard freeze, running a thin trickle from a faucet on an exterior wall relieves pressure and keeps water moving, which makes a freeze far less likely.
• Winterize the irrigation system. If you have in-ground sprinklers, shut off the supply and blow out the lines with compressed air so no water is left to freeze.

Prep the heating system

Your furnace works harder in winter than at any other time, so a little prep now avoids a no-heat emergency during a cold snap when technicians are booked solid.

• Replace the furnace filter. A clean filter is the cheapest way to keep the system running efficiently. Check it monthly through the heating season and swap it when it looks dirty.
• Book an annual service. A pre-season tune-up catches worn parts and cracked heat exchangers while a technician is still easy to schedule.
• Test the thermostat. Run the heat for a few minutes to confirm it fires up, and set your winter schedule now. If you have a smart thermostat, check that it's connected.
• Bleed the radiators. If you have hot-water heat, bleeding trapped air lets the radiators warm evenly and efficiently.

Seal the envelope

Every draft you close makes the house warmer, cheaper to heat, and less prone to cold spots where pipes can freeze. This is the highest-return work you can do on a weekend.

• Weatherstrip doors and windows. Replace any weatherstripping that's cracked or flattened, and add a door sweep to any exterior door with a visible gap at the bottom.
• Caulk gaps. Seal around window and door frames, pipe penetrations, and the foundation sill where cold air (and pests) sneak in.
• Add outlet and switch gaskets. Foam gaskets behind the cover plates on exterior walls block a surprising amount of cold air.
• Apply window film. On older single-pane windows, an insulating shrink film adds a cheap extra layer against heat loss.
• Reverse ceiling fans to clockwise. Running fans clockwise on low pushes warm air that has risen to the ceiling back down into the room.

Roof, gutters and ice dams

Winter roof problems almost always trace back to water that couldn't drain and heat that shouldn't have escaped. Address both before the snow arrives.

• Clean the gutters after most leaves have fallen. Clogged gutters overflow and freeze, forcing water under the roof edge.
• Check the roof from the ground with binoculars for missing, cracked, or lifted shingles, and fix them before snow load arrives.
• Ensure attic insulation and ventilation. Ice dams form when heat leaking into the attic melts rooftop snow that then refreezes at the cold eaves. Good insulation keeps the heat in the house, and proper ventilation keeps the roof deck cold — together they are the real fix for ice dams.

Outdoors and equipment

• Store hoses and outdoor gear somewhere dry so they don't crack in the cold.
• Winterize the lawn mower. Either run the tank dry or add fuel stabilizer, and consider changing the oil so it's ready in spring.
• Stock ice melt and a shovel before the first storm, when stores sell out fast. Keep them somewhere you can reach without going outside first.

Emergency prep

• Have a power-outage plan. Keep flashlights, batteries, and warm layers accessible, and know how you'll keep pipes from freezing if the heat goes out for an extended time.
• Test smoke and carbon-monoxide alarms and replace the batteries. CO risk rises in winter when the furnace runs constantly and windows stay shut, so working CO alarms are essential.

Frequently asked questions

At what temperature do pipes freeze?

Water pipes are generally at risk once the air around them drops to about 20°F (-6°C) or below, though the exact point depends on how exposed and how well insulated the pipe is. Pipes in unheated spaces like garages, crawlspaces, attics, and exterior walls freeze first. Keeping the house above roughly 55°F (13°C), insulating exposed pipes, and letting a faucet drip during extreme cold all lower the risk.

Should I leave the heat on when away in winter?

Yes. Keep the thermostat set no lower than about 55°F (13°C) when you're away so pipes inside walls and floors stay above freezing. Turning the heat off entirely to save money can cost far more if a pipe bursts. If you'll be gone a long time, you can also shut off the main water supply and drain the lines.

How do I prevent ice dams?

Ice dams form when heat escaping into the attic melts snow on the roof, which then refreezes at the cold eaves and traps water behind it. The best prevention is a cold roof: clean gutters so melt can drain, add or improve attic insulation to stop heat loss, and make sure the attic is well ventilated so it stays close to the outdoor temperature.

Related guides

• Fall home maintenance checklist
• How often should you change your furnace filter?
• Home maintenance schedule by month