How Cold Is It Before Pipes Burst?

Two hundred and fifty-thousand American families experience frozen and burst pipes each year, according to data from State Farm Insurance. Depending on the length of time a burst pipe goes unnoticed and the severity of the situation, this break can cause thousands of dollars in repair and replacement costs, aside from the inconvenience and disruption that ensues. Although there is a temperature threshold for pipes to burst, a number that is dependent on other factors, there are precautionary measures you can take to prevent this unpleasant occurrence.

Pipes generally burst at 20 degrees F.

Burst Pipe Temperature

The temperature alert threshold for pipes to burst as a result of cold weather is 20 degrees F, according to The Weather Channel. This number is based on field tests of residential water systems exposed to winter temperatures. The tests were conducted by the Building Research Council at the University of Illinois, which found that uninsulated pipes installed in unheated attics froze when the temperature outside was 20 degrees F. USA Today states that the temperature for bursting pipes in an unheated crawl space is also 20 degrees.

Other Factors

Although 20 degrees F has been established as the standard temperature for pipes to burst, they can burst at higher temperatures. On a windy day, air flowing through the cracks in an outside wall can freeze and burst the pipes even when the temperature is above 20 degrees F. Other factors that affect the temperature for pipes to burst include how well the pipes are insulated, and how close the pipes are to the habitable areas.

High Risk Situations

Southern states have a higher incidence of burst pipes from cold temperatures. There is a higher probability that homes in these states will be built with pipes located on the exterior of the house or in uninsulated attics, and this makes them more susceptible. Interior pipes located along exterior walls for sinks and appliances are also in danger of bursting.

Prevention Tactics

There are precautionary measures that you can take to prevent burst pipes in your home. If possible, don't install pipes in areas that are not heated, including crawl spaces, attics and other locations where they are vulnerable to cold weather. When this is unavoidable, insulate the pipes with insulation sleeves or pipe sleeves. For interior pipes on exterior walls, MSN recommends leaving your cabinet doors open so the home's heat can warm the pipes. Open both the hot and cold taps enough to allow a slow drip, which will stop the water pressure from building up.

If Your Pipes Freeze

If no water comes out of the faucet, there is a possibility that your pipes have frozen but not burst; if this is the case, turn off the water at the main shut-off valve. The Weather Channel advises that you may be able to thaw the frozen pipes with a hand-held hair dryer. With the faucet open, and starting near the faucet end of the pipe, slowly apply heat working from the warmest to the coldest part of the pipe. Do not use open flames to unthaw the pipes, since this is dangerous and could start a fire.