A frozen pipe doesn’t do its damage while it’s frozen. It does it when it thaws. The ice splits the pipe, and the moment that section warms up, water starts running into a wall, a ceiling, or a crawl space, often while you’re at work or away for the weekend. Knowing how to keep pipes from freezing matters more here than almost anywhere in the country, because a Twin Cities winter doesn’t give you one cold snap; it gives you weeks of subzero nights. Most frozen pipes we repair were in the same handful of places, and most were preventable with a few changes made before January. Here’s what temperature puts pipes at risk, where to look in your home, and what actually works.
What Temperature Do Pipes Freeze?
Water freezes at 32°F, but pipes inside a house usually don’t freeze until the outdoor temperature drops to about 20°F or below for several hours. Pipes in unheated or exposed spaces, such as garages, crawl spaces, and exterior walls, are at risk first, and wind makes it happen faster.
That 20°F figure is a rule of thumb, not a guarantee. What matters is the temperature around the pipe itself. A supply line tucked against a poorly insulated rim joist can freeze on a night when the rest of the house is warm, and a line in an attached garage can freeze well before the outdoor temperature hits zero. In a Minnesota winter, where nights well below zero are routine, every exposed line in the house will be tested at some point. So the goal isn’t to watch the forecast. It’s to make sure no pipe is left exposed to begin with.
Where Pipes Freeze in Twin Cities Homes
In our experience, frozen pipes almost always turn up in the same places:
- Exterior walls, especially kitchen sinks on outside walls, where the supply lines run through an uninsulated or poorly insulated cabinet.
- Rim joists in the basement, where the pipe runs along or through the outside edge of the house.
- Attached garages, including lines to laundry, a utility sink, or a bathroom above the garage.
- Crawl spaces and three-season porches that were added onto an older house.
- Outdoor spigots and the pipe feeding them, if they weren’t drained in the fall.
- Bathrooms over unheated spaces, such as a bathroom above a garage or cantilevered floor.
Older homes carry more risk. In St. Paul, the median home was built in the early 1950s and a large share predate World War II. Neighborhoods like Highland Park, Macalester-Groveland, and Como have plenty of homes where plumbing was rerouted during a remodel, sometimes through a wall that was never insulated. Galvanized steel lines in homes built between the 1940s and 1980s are also harder to protect, since corrosion inside the pipe narrows the opening and a small ice plug can block flow entirely.
How to Keep Pipes From Freezing: The Checklist
Here’s how to prevent frozen pipes, starting with what to do in the fall and ending with what to do on the coldest nights.
Before the first cold snap (October–November):
- Winterize outdoor faucets. Disconnect hoses, close the interior shut-off, and drain the line. Our step-by-step guide to how to winterize your outdoor spigots.
- Insulate exposed pipes. Foam pipe sleeves on any line in a garage, crawl space, or along the rim joist. Seal gaps where pipes pass through exterior walls with caulk or spray foam.
- Know where your main shut-off is. Everyone in the house should be able to find it and close it. If it’s a stiff old gate valve that won’t turn, get it replaced now, not during a burst pipe.
- Add heat cable where insulation isn’t enough. A UL-listed, thermostatically controlled heat cable works well on short runs in a crawl space or garage. Follow the manufacturer’s instructions exactly.
During a cold snap (below about 0°F):
- Keep the thermostat steady, day and night. Setting it back overnight is when pipes on exterior walls get too cold. If you’re away, don’t set it below 55°F.
- Open cabinet doors under sinks on exterior walls so warm air from the room reaches the pipes.
- Let a faucet drip. A slow drip from the faucet farthest from where water enters the house relieves pressure and keeps water moving. On a single-handle faucet, set it to the middle so both hot and cold lines drip.
- Keep the garage door closed if water lines run through it.
Leaving for a winter trip:
- Set the heat to at least 55°F, and ask someone to check the house daily. For longer trips, shut off the main water supply and open the faucets to drain the lines. That’s the most effective way to winterize house plumbing when no one’s home.
Have a trouble spot that freezes every winter? Call Twin Cities Premier Plumbing at (763) 343-9806. We’ll find why that line keeps freezing and reroute, insulate, or protect it so you’re not dealing with it again in February.
Signs of Frozen Pipes
The most common signs of frozen pipes are:
- A faucet that produces only a trickle, or nothing at all, on a cold morning
- Frost or condensation on an exposed section of pipe
- A toilet that won’t refill
- Bulging or a visible crack in the pipe
- An odd smell from a drain (a frozen line can back gases up into the house)
- Water stains or damp drywall on an exterior wall or ceiling
If a faucet stops working on a cold morning, assume it’s frozen. Leave the faucet open, close the main shut-off if you see a crack or any water leaking, and call a plumber. Don’t use an open flame, propane torch, or high-heat appliance to thaw a pipe; that’s a fire risk and can damage the pipe itself. If the pipe has already split, our emergency plumbing team handles burst pipes around the clock, and our leak repair service fixes the damaged section once the water’s off.
Fixing a Pipe That Freezes Every Year
Some pipes freeze every winter no matter how many faucets you drip. That’s almost always a routing problem, not a weather problem. The line runs through an exterior wall with little insulation, through a garage, or right against the rim joist.
The permanent fixes are:
- Rerouting the line through a heated interior wall or joist space.
- Adding insulation behind the pipe, between it and the cold exterior side, not just around it.
- Replacing old copper or galvanized pipe with PEX-A. PEX-A can expand when water freezes inside it, so it’s far less likely to burst than rigid pipe. It isn’t freeze-proof, and it still needs to be protected, but it adds real margin in a problem area.
We do this kind of work as part of our pipe repair and repiping service, and for older homes with galvanized supply lines, fixing the problem section is often the right time to talk about repiping the rest.
Frequently Asked Questions
At what temperature should you let faucets drip? When outdoor temperatures are forecast to drop to about 20°F or below, drip faucets on exterior walls or those that have frozen before. In a Minnesota winter, that means most subzero nights.
Should I drip hot or cold water to keep pipes from freezing? Both lines can freeze, so if the faucet has a single handle, set it to the middle so hot and cold both drip. For separate handles, open both slightly. Cold lines are usually more exposed, so if you choose one, choose cold.
Does homeowners insurance cover frozen pipes? Many policies cover sudden damage from a burst pipe, but they may exclude damage if the home wasn’t adequately heated or maintained. Check your policy and call your agent. Photos of the damage and a plumber’s written repair report help any claim.
Will PEX pipe freeze? Yes, water in PEX can freeze. The difference is that PEX-A usually expands rather than splitting, so it’s much less likely to burst. It still needs insulation and protection in cold spaces.
The Bottom Line
The best way to keep pipes from freezing is to handle it before winter starts: drain the outdoor spigots, insulate exposed lines, and fix the routing on any pipe that has frozen before. Then, on the coldest nights, keep the heat steady, open the cabinets, and let a faucet drip. A pipe that never gets cold is a pipe that never bursts.
Call Twin Cities Premier Plumbing at (763) 343-9806 to have your home’s trouble spots checked before the first subzero night. We serve Minneapolis, St. Paul, Plymouth, Maple Grove, Bloomington, and communities across the Twin Cities metro.