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Ask the Carpenter: How to keep your pipes from freezing

Ask the Expert
Burst-Pipe-Photo
As freezing water expands, it causes the pressure inside the pipes to increase, often resulting in a pipe break. Ian Redding/Shutterstock

It’s a job that’s been the butt of jokes (pun intended), but when the temperatures crash, no one jokes around about plumbers.

Freezing temperatures are a water pipe’s nemesis, which is why I always tell my clients: Ice expands, pipes don’t. Every winter some 250,000 families in the United States see at least one room in their home damaged by water pipes freezing and breaking, according to State Farm Fire and Casualty Co.

As freezing water expands, it causes the pressure inside the pipes to increase, often resulting in a pipe break. A pipe will not usually burst at the frozen part, but somewhere between the freeze and the faucet.

The ice blockage can cause thousands of pounds of water pressure to build up. Just one pipe burst can unleash gallons of water to run behind walls and ceilings, causing thousands of dollars in damage to your house and personal items. The good news is that many home insurance policies will cover the damage — provided you can prove that you took measures to prevent the pipe from freezing. For example, many policies say there is coverage if you can show that you either shut off the water supply/drained your system or kept your home heated when it was unoccupied.

Insurance coverage for burst pipes usually includes:

 Demo work to access the broken pipe, such as opening up a wall or ceiling;

 Necessary repairs or replacement for any damaged property, such as drying out flooded carpets or replacing destroyed furniture, hardwood, or appliances;

 Repair costs to the pipes, walls, and structure.

Can frozen pipes be prevented?

When I was a kid and we experienced extreme cold snaps, my mom would open the cabinet doors under the kitchen sink to expose the pipes to more heat and leave our faucets dripping to prevent the pipes from freezing.

I always thought that leaving the water dripping prevented the pipes from freezing, but that’s not exactly correct. It’s not the small flow of water that prevents freezing; a dripping faucet relieves pressure buildup in the water pipes to prevent them from bursting as a result of ice buildup. The dripping faucet can help slow freezing, but the pipes can still freeze.

Prevention

To avoid frozen pipes, homeowners should have adequate insulation and seal air leaks near pipes that run along outside walls, floor joists, and in crawl spaces. Disconnecting garden hoses, wrapping exposed pipes with insulating sleeves, and sealing foundation cracks that let in Arctic air all help. Below are eight tips to prevent frozen pipes:

1. Install anti-freeze faucets on your exterior

These faucets have a long stem that extends through the house wall and into the warmer section of the house. Water doesn’t stand in the portion of the pipe or faucet outside the wall, where it could freeze.

2. Seal all drafts and leaks in the basement

Check all penetrations into your home (cable and phone wires, pipes, windows, etc.) Use expanding foam to seal these gaps.

3. Insulate the exterior rim joists in your basement

These are the outermost sections of your basement. Insulating the rim joists here helps a lot, and you’ll notice a difference in the basement temperature. If you have open stairs going out to a bulkhead, simply adding an exterior door, or even a storm door, will warm up your basement.

4. Make sure all basement windows close tightly and the glass is intact to keep out drafts and cold

5. Insulate your pipes

Use thick foam or fiberglass sleeves, paying special attention to the pipes closest to the exterior walls; these are the ones that usually freeze first. Consider rerouting and insulating vulnerable water pipes, moving them to an area farther into the house.

6. Keep your heat at a minimum of 55 degrees Fahrenheit

Never shut off your heat in the winter.

7. Install electric heat tapes on vulnerable pipes

8. Add heat to problem areas such as crawl spaces, closed rooms, etc.

Note: Before you go on vacation, set the heat to 55 degrees, shut of the water main, and consider draining the system by opening all the faucets (hot and cold) in the house. You may think you’re saving money by lowering the heat more, but there could be a disaster waiting for you on your return.

What do you do if a pipe freezes or bursts?

If your pipes freeze

 Open all faucets;

 Remove insulation;

 Apply heat to the section of pipe using an electric heating pad, a hair dryer, or a portable space heater (kept away from flammable materials), or by wrapping pipes with towels soaked in hot water. Do not use a blowtorch, kerosene or propane heater, charcoal stove, or other device that uses an open flame. Don’t use electrical appliances while standing in water; you could get electrocuted;

 Slowly apply heat, starting close to the faucet end of the pipe, with the faucet open. Work toward the coldest section;

 If all else fails, call your plumber.

If your pipes burst

 Shut off the water immediately to prevent additional damage. (Did you label your water shutoffs?);

 Remove standing water with wet vacuums, and use specialty fans and dehumidifiers for drying;

 Discard damaged, water-soaked wallboard, property, and furniture;

 Contact a plumber to restore the water;

 Call your insurance company;

 Consider hiring an emergency water-mitigation service that can properly dry out the damaged area.

Stay warm and informed.

Rob Robillard is a general contractor, carpenter, editor of AConcordCarpenter.com, and principal of a carpentry and renovation business. Send your questions to homerepair@globe.com or tweet them to @robertrobillard. Subscribe to our newsletter at pages.email.bostonglobe.com/AddressSignUp