Frozen Pipes: The 20-Minute Checklist Before the First Cold Night
If you live anywhere that sees a hard freeze, you know the drill: the forecast drops below 20°F, and suddenly everyone is talking about pipes. It’s not hype. A burst pipe is one of the most expensive and damaging home emergencies you can face — the average claim costs about $15,000, according to the Insurance Information Institute, and that’s before you deal with mold, drywall, and weeks of contractors in your kitchen.
The good news: most frozen pipes are preventable, and the prevention work takes about 20 minutes. This weekend, before the first real cold night hits your area, run through this checklist. It covers the pipes you can see, the ones you can’t, and the habits that keep water moving when it matters most.
And if you’ve already had a cold snap and you’re wondering whether you’re too late — skip to the last section. There’s one sign that means you need to act right now, not tomorrow morning.
Why pipes freeze in the first place
Water expands by roughly 9 percent when it freezes, and it does so with remarkable force. A half-inch copper pipe can withstand about 1,100 pounds per square inch of pressure at room temperature, but ice forming inside a closed pipe creates pressures that can exceed 2,000 psi. That’s why pipes don’t just crack — they split along their length, and by the time you see the damage, the water has been running for hours.
Pipes freeze when three things line up: the outdoor temperature drops below 20°F, the pipe is in an unheated space, and there’s little or no water movement. Your most vulnerable pipes are almost always in the basement, crawl space, attic, garage, or along exterior walls. Any pipe that shares a wall with the outdoors is at risk, even if the room on the other side is warm.
This is not a rare problem. The American Red Cross reports that frozen pipes are one of the most common winter home emergencies, and they’re entirely avoidable with basic preparation.
The 20-minute checklist
Set a timer. Grab a flashlight, a tape measure, and a $15 tube of foam pipe insulation. Here’s what to do.
1. Find every pipe in an unheated space
Start in your basement or crawl space and trace your water lines. Look for any pipe that runs along an exterior wall, near a foundation vent, or through the garage. Don’t forget the laundry room and the utility closet — those often have plumbing against an outside wall.
Mark each vulnerable pipe with a piece of tape as you go. You’ll need to come back to these in a minute.
2. Insulate the pipes you can reach
Foam pipe insulation is cheap, easy to cut with scissors, and takes about a minute per pipe. Slip it over the pipe and tape the seam. Pay extra attention to elbows and joints — that’s where ice tends to form first, according to the American Society of Plumbing Engineers.
For pipes that run through gaps in exterior walls, spray foam or fiberglass insulation works better than foam sleeves. If you can’t reach the pipe itself, seal the gap around it to keep cold air out.
3. Seal the air leaks
Cold air finds the path of least resistance. Check around your foundation, your exterior faucets, and any vents or penetrations in exterior walls. A tube of exterior caulk and a can of spray foam will handle most of these. For crawl space vents, consider covering them with insulated panels — many homes have those vents for summer airflow only, and leaving them open in winter is like running your furnace with a window open.
4. Disconnect the garden hoses
This is the most common mistake, and it’s the easiest to fix. Disconnect every garden hose, drain the water out of it, and store it somewhere it won’t freeze. Close the shut-off valve to the outdoor spigot if you have one, then open the spigot to drain the line. Leaving a hose attached holds water in the pipe and the spigot, both of which will freeze and crack.
If your outdoor spigot doesn’t have a shut-off valve, you can buy a foam cover for a few dollars. It won’t protect the pipe inside the wall, but it will protect the spigot itself.
5. Know where your main shut-off is
This is the most important five minutes of the whole checklist, and almost nobody does it until it’s too late. Find the main water shut-off for your house — usually in the basement, crawl space, or near the water meter. Turn it off once and back on again to make sure it works. If it’s stuck, call a plumber now, while you have time, not at 2 a.m. when water is pouring through your ceiling.
Also find the shut-off valves for individual fixtures: the washing machine, the dishwasher, and any bathroom sinks. They’re usually under the sink or behind the appliance. Make sure you can turn them by hand.
6. Set your thermostat — and don’t turn it down
The temperature inside your walls is not the same as the temperature in your living room. If you set your thermostat to 55°F at night, the pipes inside your walls can drop below freezing, especially in an older home with little insulation in the wall cavities.
The American Red Cross recommends keeping your thermostat at 55°F or higher, even when you’re away. That’s the absolute minimum. If you’re planning to leave for more than a day, you’re better off leaving the heat on at 60°F and paying the extra couple of dollars than coming home to a flooded basement.
7. Open the cabinet doors under sinks
On a night when the temperature is forecast to drop well below freezing, open the cabinet doors under your kitchen and bathroom sinks. That lets warm room air circulate around the pipes. It doesn’t take much — a few degrees of warmth can make the difference between a pipe that survives and one that splits.
If your sinks are against an exterior wall, you can also leave the faucet dripping overnight. A slow trickle — about the size of a pencil lead — keeps water moving through the pipe, which makes it much harder for ice to form. The cost of a night of dripping water is pennies; the cost of a burst pipe is thousands.
8. Check the areas you can’t see
If you have a sump pump, check the discharge line. If it runs outside and the pipe is exposed, a frozen line can back water up into the pit and eventually into your basement. Wrap that pipe too, and consider a heat tape — a low-voltage heating element that wraps around the pipe and plugs in. Heat tape is cheap insurance for the most exposed pipes, and it solves the problem of pipes that are just too hard to insulate.
What to do if a pipe actually freezes
Even with perfect preparation, pipes can freeze. Here’s what to do — and what not to do.
When you open a faucet and nothing comes out, or only a trickle, you have a frozen pipe. The first step is to find where it’s frozen. Run your hand along the pipe and feel for the coldest spot. Ice feels noticeably colder than the surrounding pipe, and you may see frost on the outside.
Open the faucet that the pipe serves before you start thawing. That gives the water a place to go as the ice melts and relieves pressure inside the pipe.
Thaw the pipe gently. A hair dryer, a portable space heater, or towels soaked in hot water all work. Start from the faucet end and work toward the frozen section — never from the middle. Work slowly; you’re not trying to melt the ice instantly, you’re trying to warm the pipe enough that the water inside begins to flow.
Never, under any circumstances, use an open flame. A propane torch or blowtorch will heat the pipe unevenly and can start a fire inside your walls, or you can overheat the water and create steam that bursts the pipe from the inside. The Minneapolis Fire Department has seen every version of this, and every version ends badly.
If the pipe is buried in a wall or under a slab, you can’t thaw it yourself. Call a plumber. They have specialized equipment — heat blankets, induction thawing tools — that can handle pipes you can’t reach.
The one sign it’s already too late
Here’s the part nobody wants to hear. If your pipes have already frozen once this winter, they will freeze again. That’s not a scare tactic — it’s physics. The conditions that caused the freeze haven’t changed. The pipe is still in the same cold spot, still with the same insulation (or lack of it), still exposed to the same temperature drop.
But the sign that it’s already too late, that you need to act right now, is this: the pipe looks swollen, or you see a small crack with the tiniest bit of moisture, or you hear a hissing sound near the pipe when the water is on.
That’s a pipe that has already expanded under the pressure of ice, and it’s already compromised. When it thaws, that crack will open fully, and you’ll have water where you don’t want it. Not might — will.
If you see that sign, do not thaw the pipe. Do not turn the water back on. Call a plumber immediately. A plumber can repair or replace the damaged section before it floods your home. Waiting until “tomorrow morning” to check on it is how you end up with a ceiling collapse.
The other sign that should make you move fast: your water pressure drops noticeably, but the faucets still produce water. That often means a pipe has burst somewhere you can’t see — inside a wall, under the floor, in the ceiling. The water is running into the structure, not into your sink. Turn off the main shut-off valve right now, and call a plumber. The longer you wait, the more damage the water does — and the higher your claim gets.
Do the checklist now, not on the cold night
The trick with frozen pipes is that you never get a warning. You don’t get a “pipe’s about to freeze” notification. You get a wet floor at 3 a.m., or you don’t. The 20 minutes you spend this weekend — finding the vulnerable pipes, insulating them, sealing the gaps, learning your shut-off valve — is the difference between a normal winter and a $15,000 insurance claim.
And if you’ve already had a freeze, or you notice that swollen pipe or that hiss of air, don’t wait it out. A burst pipe doesn’t get better with time. The only question is how much damage you’re willing to accept while you decide.
This weekend, before the first cold night, walk your basement. Trace your pipes. Know your shut-off. It takes 20 minutes, and you’ll never miss those 20 minutes more than the night you don’t take them.
Need emergency help with a frozen or burst pipe? We’re available around the clock at Goldberg Plumbing. Contact us for 24/7 emergency service.