Why Pipes Burst in Winter and How to Prevent It

Water expands by about 9 percent when it freezes. If a pipe is full of water and the temperature drops below freezing, the ice forms and pushes against the pipe walls. That pressure can cause a crack or a complete break, even in metal or plastic pipes.

The risk is highest in pipes located in unheated crawl spaces, garages, or along exterior walls. A sudden cold snap after a mild spell can catch you off guard. In a mild marine climate with wet winters and dry summers, freezing is less common, but a hard freeze still happens.

Insulate pipes in unheated areas using foam pipe sleeves or heat tape. Focus on the attic, basement, garage, and exterior walls. Seal any gaps or cracks where cold air can reach pipes, such as around vents or where pipes enter the house.

During a hard freeze, let a faucet drip slowly. Moving water is less likely to freeze. Open cabinet doors under sinks to let warm air circulate. Keep the thermostat set to at least 55 degrees Fahrenheit, even when you are away.

• Wrap pipes with foam insulation or heat tape
• Seal air leaks with caulk or spray foam
• Let faucets drip during freezing nights
• Open cabinet doors to warm the pipes
• Keep the heat on, even when away
• Know where your main shutoff valve is

For pipes in exterior walls, consider having a plumber reroute them to warmer areas or add insulation behind the wall. A smart thermostat can alert you if the house gets too cold. If you live in Kirkland, keep your shutoff valve location written down.

After a burst, inspect pipes for cracks and replace damaged sections. Check insulation for gaps and add more where needed. If you have water damage, a water damage inspection can reveal hidden moisture. Structural drying and dehumidification help prevent mold and rot.