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How to Prevent Pipes from Freezing

Old Man Winter and his girlfriend Mother Nature can wreak havoc with your home's plumbing pipes if you don't protect them from freezing. Most people only have this happen to them once if their house turns into Niagara or Victoria Falls once the pipes thaw out and they're not home to stop the damage.

I had my own kitchen sink water supply lines freeze up here in my house in New Hampshire a few years back on a bitter cold night. I didn't build the home, but my research showed the builder was among the best in the area.

I guess he was sick the day the carpenters installed the downdraft ductwork that blew cooktop exhaust air to the outdoors. The gaps around the duct hood as it passed through the exterior wall were large enough to taxi a 747 through. Maybe I'm exaggerating a little bit.

Poor building and plumbing practices are the most common cause of frozen water supply lines, but you as a homeowner can make some mistakes too. Here's a handy list of ways to prevent your water pipes from freezing in the winter.

Among other things, I'm a master plumber, so be sure to read the last paragraph below if you went to other websites that told you to let faucets drip or have a very thin stream of water flowing to prevent burst pipes.

Degree of Difficulty: hammer-1-5

Step One: Pay your utility bills on time. You need an uninterrupted flow of natural gas, electricity or fuel oil to keep your heat on. Your utility company may not be allowed to turn off your power and fuel in the winter, but mistakes happen.

Step Two: Consider investing in a 3500-watt generator in case your power goes out in a freak storm. Many storms are followed by a reinforcing shot of cold Arctic air and it could be days before power comes back on. In the meantime, your pipes freeze simply from the lack of enough electricity to power your furnace or boiler. Figure out ahead of time how you'll get the furnace or boiler to work using the generator. They're always hard-wired into the circuit breaker panel.

Step Three: Do a check of your basement or crawlspace. Look for air leaks around windows, air vents, etc. Stuff any cracks you see with fiberglass insulation or use great expanding foam in spray cans if the air temperature is above what it says on the can label. Always read the instructions on products as to the temperature range products can be installed.

Big Gap Filler Spray Foam

If you have a basement, vast amounts of cold air can pass under the sill plate where the wood framing sits on top of your masonry foundation. Caulk or fill gaps with insulation. Apply duct tape if necessary until you can do it right in warmer weather. Install fiberglass insulation batts against the band board at the end of joists where they rest on the wood sill plate.

Step Four: Do a walk around of your house and look at exterior walls where you have plumbing fixtures. See if you can spy cracks, holes or anything unusual where air could be leaking into your home. This is very hard to do if you have vinyl siding. By it's very nature vinyl siding allows massive amounts of air to pass through it.

Step Five: Plumbing supply lines can freeze from cold air that drops down from your attic into interior walls. This confounds many as they can't figure how pipes on an interior wall freeze up. The culprit are holes in the top plate of the interior wall where plumbing drain line vent pipes or electric cables were never sealed during construction.

These holes can sometimes be located by looking at the insulation. If you see dark or black areas in the otherwise colored or white insulation, these spots can be dirt that's being trapped by the insulation much like your car or furnace air filter. Air can flow through the gaps all year and the dirt builds up in the insulation.

I guarantee you if you pull back the insulation in these areas you'll see holes, gaps or cracks leading down into the bowels of your home. Cold air drops into these in the winter like a stone drops to the bottom of a lake.

Step Six: Keep kitchen sink and bath vanity cabinet doors open on bitter cold days and nights. This may allow enough heat to contact the pipes to help temper them to prevent freezing. It's a longshot, but sometimes works.

Step Seven: Consider using heat tape on pipes to help raise their temperature. Talk to your local fire department fire prevention officer BEFORE installing these. Many houses have burned because of heat tape that's improperly installed.

Step Eight: Re-route water supply lines so they're out of the danger zone. Suck it up and get water lines out of exterior walls. You'll pay dearly for this, but you'll be able to never have to worry about pipes freezing if you have them on the inside of your home.

Summary: You can also allow water to run in faucets as a last resort. This might not be as expensive as you think and it wastes water unless you devise some way to save it.

But as a last resort, the tradeoff of the extra $20 or so of water will be far less than the hundreds of dollars you spend with a plumber to fix split pipes and the thousands of dollars of damage burst water pipes cause.

You need to have a stream of water at least one-quarter inch wide to ensure the pipes will not freeze. Ignore advice from others about just letting the faucets drip or to have a tiny stream of water. I've been a master plumber for over 35 years and can tell you that's not enough water flow.

Column HT037

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5 Responses to How to Prevent Pipes from Freezing

  1. Hi Tim,

    If I live in a condo built as a condo (rather than an apartment conversion) in Atlanta, GA in 1973, at what temperature should I worry about pipes freezing? Max cold this month was 12°F and I took all precautions (leave heat on, open cabinet doors, wrap outside faucets, let faucets run hot&cold 1/4" stream) with good results, i.e., no pipes froze. That temp is unusually cold; usually we get only upper 20's. Our condo association puts out freeze warnings if it threatens to freeze at all. Isn't that excessive?

    • Well, if the condo was built RIGHT, you shouldn't ever have to worry as long as the heat is on and the room temperature in the CONDITIONED spaces of your home are above 40 F.

  2. In remodeling our kitchen, the building inspectors wanted me to put the pipes I was adding in the middle of the outside wall, so they wouldn't get punctured. But that's what steel plates over the places pipes go through studs are for ...

    Putting pipes in the middle, of course, is a problem: It puts insulation between the pipe and the warm room, making the pipe colder than the room. For example, if the room is 70 deg.F. and the outside is -10 deg.F., a delta of 80 degrees, the middle of the wall will be 70 - 40 = 30 degrees, below freezing!

    After the inspection, I moved the pipes to the room side of the insulation!

    You may ask why I didn't put the pipes outside the wall in the room: our home is built on a slab and the kitchen pipes come out of the concrete inside the wall.

    You can be sure when I look at buying a house in the future that I will consider where the pipes are in relation to the outside wall.

    For our bathroom/laundry room remodel, all of the pipes were above the slab, so I had the plumber abandon the old pipes in the outside wall and put in new pipes on the room side of the wall. This took up some space in the bathroom under-sink cabinet, but the peace of mind is well worth the space given up.

  3. I have this "instant hot water" system which is a zone circulator pump connected between hot and cold water pipe under kitchen sink. I press a button near the kitchen sink when I want hot water, and it starts pumping hot water back into the cold water pipe until the water gets up to a preset temperature. Is there a sensor available that I can use to detect freezing that will start this process automatically on demand to prevent freezing ?

  4. Open cabinet / & closet doors to let warmer air get to any covered pipes.
    I modified a styro type outside faucet cover to hold a night light wattage / Xmas light ( robbed for socket ). The light provides enough head to keep from freezing.
    I plug in an extension cord when below 15 degree temp is forecast.

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