How Cold Does It Have to Get for Pipes to Freeze?

The general rule is that pipes start to freeze when the air temperature falls to 20 degrees Fahrenheit or lower. That is the point where water inside an unprotected pipe can turn to ice and expand, putting pressure on the pipe walls. Pipes in unheated areas, like garages or basements, are the most vulnerable.

Your home's insulation and the pipe's location matter a lot. A pipe running through an exterior wall with little insulation can freeze at temperatures closer to 25 degrees. Wind chill can also pull heat away from your home, making the effective temperature lower than what the thermometer shows.

When water freezes, it expands by about 9 percent. That expansion creates tremendous pressure inside the pipe, often causing a crack or a complete rupture. When the ice thaws, water gushes out, flooding your home in a short time.

Even a small crack can release hundreds of gallons of water per hour. The water soaks into drywall, flooring, and insulation, leading to structural damage and creating conditions for mold growth. The longer water sits, the more extensive the damage becomes.

If a pipe has already burst, you are dealing with active water damage. Shut off your water supply and electricity in the affected area if it is safe to do so. Then call local water damage pros to assess the situation and start cleanup.

The pros can extract standing water, dry out walls and floors, and inspect for hidden moisture. They also check for mold growth, which can start within 24 to 48 hours in damp conditions. For help with drywall, flooring, or ceiling repairs, see the related services below.

• Shut off the water main immediately
• Turn off electricity in the flooded area if safe
• Remove valuables and furniture from the wet area
• Document the damage with photos for your insurance records
• Check your policy for coverage details. Policies vary, and your insurer decides what is covered.