How to Prepare Your House for a Hard Freeze

Before a hard freeze, drip the faucets on exterior walls, open the cabinet doors under sinks on those walls, keep the heat at 55 degrees or higher, and make sure hoses are off and outdoor faucets are drained. If a pipe still freezes, shut off the water to it before it thaws, because a split pipe leaks the moment the ice melts.

The night-before list

The pipes most likely to freeze are the ones near outside walls, in unheated spaces, or exposed to wind. Work through this list in the afternoon or evening before temperatures drop.

• Disconnect hoses and drain outdoor faucets. If you have not done it yet, this comes first. Close the indoor shutoff if there is one and leave the outdoor tap open. The full steps are in how to winterize outdoor faucets.

• Drip faucets on exterior walls. Pick the faucets farthest from where water enters the house, and any on outside walls. A slow, steady drip from both hot and cold is enough. Moving water is harder to freeze, and an open faucet relieves pressure if ice does form.

• Open cabinet doors under sinks on outside walls. Kitchen and bathroom pipes often run inside cabinets against exterior walls. Opening the doors lets room heat reach them. Move cleaning products out of reach if you have kids or pets.

• Keep the heat at 55 degrees or higher. Do not set the thermostat way down at night or while you are away. The walls and floors where pipes run are colder than the room, so the thermostat needs some margin.

• Keep the garage door closed. If you have an attached garage with water lines or a water heater in it, keep the big door shut. A garage can drop to outdoor temperature fast with the door open.

• Cover or close crawl space vents (if you have them). If your house sits on a vented crawl space, close the vents or cover them with foam blocks for the cold snap. Open them again when the weather warms, since crawl spaces need airflow the rest of the year.

• Wrap exposed pipes. Foam pipe sleeves slip on in minutes. Focus on pipes in the garage, crawl space, attic, or unheated basement. Hardware stores sell out before a big freeze, so buy them early.

• Know where the main water shutoff is. Find it, make sure it turns, and keep a flashlight near it. If a pipe bursts, shutting off the water quickly is the single biggest factor in how much damage you end up with.

If a pipe freezes

The sign is a faucet that gives only a trickle or nothing at all during cold weather. Frost on a visible pipe or a bulge in it are also signs.

1. Leave the faucet open. As the ice melts, flowing water helps thaw the rest of the pipe.
2. Warm the pipe gently, starting near the faucet and working back. A hair dryer, a heating pad, or towels soaked in hot water all work.
3. Never use an open flame, like a propane torch, to thaw a pipe. It is a fire risk and can damage the pipe.
4. If you cannot find or reach the frozen section, call a plumber.
5. Check the pipe carefully once water flows. If you see or hear a leak, shut off the water right away.

If a pipe bursts

1. Shut off the main water valve.
2. If water is near outlets, light fixtures, or the electrical panel, stay out of the water and shut off power to that area at the breaker only if you can reach it safely.
3. Open faucets to drain what is left in the lines.
4. Call a plumber, then take photos for your insurance company before you start cleaning up.
5. Move what you can out of the water and start drying the area. Wet drywall and insulation that stay wet for more than a day or two can start to grow mold.

Once the cold snap passes, the winter checklist covers the rest of the season.