Seattle's Home Inspection Team (206) 295-4330
: Tips for Thawing Frozen Pipes

Tips for Thawing Frozen Pipes

Our Home Page - Articles and Advice - Our Reports - Testimonials - Our Company - Services

Since this is such an unusual cold snap in the Seattle (18 degrees this morning here), I thought I would pass along this article on thawing frozen pipes, just in case this happens to you.  The plumbers of the city are going to be really busy today!

During cold weather, pipes in your walls, attic or under your floor can freeze. Frozen pipes can crack or burst because as water freezes, it expands. With enough expansion, pipes will develop cracks. The cracks may not be visible but they will leak nonetheless when the ice melts. If a frozen section of pipe is caught in time, there may be no damage; but it must be thawed before any more freezing occurs. Protecting pipes from freezing is the best plan, but if you are reading this, then that will have to take a backseat to thawing the frozen pipes.

If there is a slow trickle at the faucet, leave the faucet open. The flowing water will help to prevent a complete frozen blockage. In addition, the flowing water may help to melt the existing partial blockage. Continue with the following steps to ensure the pipes thaw completely.

Locate the Frozen Pipe

The first step to thaw frozen pipes is to locate the section of pipe and turn off the local water supply to it. To determine whether a section of pipe is frozen, simply feel it. Frozen pipe will feel very cold, while pipe with free flowing water will feel notably warmer. Try to find a pipe through which water is still flowing to use as a comparison. After a couple minutes of running, the pipe should be around 50 degrees or so. If you have an infrared thermometer, it makes finding frozen pipes easy.

How to repair a frozen or broken pipe

If there is no water at any of the taps in the house, the main water line may be frozen somewhere between the meter and where the water line enters the house. Typically this line is buried, and buried at the locally mandated depth to protect it from freezing. There is little to be done to thaw a buried water line. The only course of action is to rebury the line deeper, below the frost line, to ensure against future freezes.

In serious freezes, there may be multiple frozen sections of pipe in various vulnerable locations. The first point to inspect is where the water line comes out of the ground and where it enters your home. Any exposed pipe is vulnerable if it is exposed to outside air, even if it is in your attic, unconditioned basement or crawlspace.

Exterior walls, even when insulated, may get cold enough to freeze pipes inside the wall. Pipes that pass near an exterior vent in your home are subjected to colder air and are a good place to start hunting. If there is no water in only one part of the house, then the frozen pipe is probably in an exterior wall, attic, crawl space or basement.

Once you locate the frozen section, if the pipe is accessible, inspect it visually and by running your fingers over the pipe to feel for cracks or splits. If you find damage, you may want to get repair materials ready before thawing the pipe. If the pipe is not accessible, read on for techniques to deal with hard to reach pipes.

Before you start the thawing process, open water taps on the frozen line to allow water, steam or pressure to escape. This will allow water to drain out as the ice melts and will tell you if you have succeeded in melting the obstruction.

How you heat the pipe depends upon the type of pipe and the location. But in all cases start nearest the tap and work outward. Never heat a pipe with direct flame or boiling water. Heating a pipe too quickly can result in bursting, damage and injury.

Accessible pipes can be heated with a hair dryer. Keep the dryer moving and do not focus it on any one place too long.

Hot wet rags can be used to heat pipes. Simply immerse a rag in hot water (about 110 degrees F) and wrap it around the pipe. Replace the rag when it cools.

A grounded, water resistant heating pad can be wrapped around the pipe and set to the lowest heat setting.

Thawing Metal pipes

While a flame can be used to heat accessible copper or steel pipes, it is not recommended to use a direct flame on any pipe as this increases the risk of damage to the pipe as well as presenting a fire risk. Never heat the pipe any warmer than you can comfortably tolerate holding the pipe bare handed and always use a flame spreader to diffuse the flame. Never use a flame on plastic pipe.

Accessible pipes can be heated with a hair dryer. Keep the dryer moving and do not focus it on any one place too long.

Hot wet rags can be used to heat pipes. Simply immerse a rag in hot water and wrap it around the pipe. If you are able to catch water from under the pipe, you can go a step further by pouring hot (not boiling) water over the rags.

A grounded, water resistant heating pad can be wrapped around the pipe and set to the lowest heat setting.

Thawing Inaccessible pipes

Frozen water pipes located in inaccessible locations can be warmed by raising the ambient temperature. In cases where the pipe is located in an exterior facing wall, open cabinets to allow warm interior air to warm the cabinet and wall. Locating pipes may require a little detective work. First consider, most pipes travel through walls in the most direct route to get to the room they service. The water lines are likely to be near the rooms they service. Raising the indoor temperature will increase the temperature in all rooms and help heat pipes in exterior walls. But direct application of heat where the pipes run will speed the process even more.

You may place a heat lamp or portable heater facing the wall to warm it. Before using a heat source remove any combustible materials and follow all manufacturers safety warnings about how close it may be placed to the wall or other obstruction. In the absence of other warnings, place the heat source no closer than 18 inches from the wall or obstruction.

Heating this way will take time, but it does work.



If you find this information useful, don't keep us a secret!
List us on any of your favorite networking / bookmarking sites
Bookmark and Share



Great information, I wish I had this back when I was in my first home.  The pipes froze up one year and I had quite a time getting them unforzen.  Thanks!

Posted by Joyce Gebhart (The Creig Nothrop Team of Long & Foster) over 9 years ago

This is such a useful article, JJ and Suzanne.  Home owners need to know what they can do when they have a frozen pipe, and you've laid out the suggestions and steps perfectly.

Posted by Marie Haydock, Simplifying Real Estate (Evergreen Global Homes & Land | RSVP Real Estate) over 9 years ago

This blog does not allow anonymous comments