A frozen pipe is sometimes a thing you can fix yourself. It’s also a thing you can turn into a much bigger problem in about ninety seconds, and most of that comes down to what you do first.
It’s the wall temperature, not the porch thermometer
Pipes get vulnerable when the air around them hits roughly 20 degrees. Around them. Not outside. What matters is the crawlspace, the attic, the cabinet on the exterior wall where warm air never quite reaches.
Which is why Minnesota is harder on plumbing than places that see colder single nights. We get stretches. Days of it. A wall cavity that would have been fine for one night gives up on night four.
Confirm it before you start
Turn on a faucet. A trickle instead of a stream means suspect ice.
Check the usual spots first. Exterior walls, crawlspaces, attics, unheated garages, and wherever the service line comes in through the foundation.
Then check every other faucet in the house. If one froze, others nearby probably did too. People find the second one after the first one bursts.
Open the faucet before any heat
This gets skipped constantly and it matters more than the heat source does.
Leave it open while you work. As ice melts, water moving through the thawed section helps clear the rest. A closed faucet means the melt has nowhere to go.
Heat: what’s fine, what isn’t
Fine: an electric heating pad wrapped around the pipe, a hair dryer, a space heater kept well clear of anything flammable, towels soaked in hot water.
Not fine: blowtorch, kerosene or propane heater, charcoal stove, any open flame at all. This is the one that turns a plumbing bill into a house fire. Someone tries it every winter.
Work from the faucet end back toward the frozen section so the melt has an escape route, and keep going until full pressure returns. If you can’t find the frozen section or can’t reach it, stop and call a plumber. Opening a wall badly costs more than the call does.
Call both trades at once
Here’s the part almost nobody explains.
If the pipe has already let go, you need two trades, and they aren’t the same trade. A licensed plumber repairs the pipe. A restoration crew extracts the water and dries the structure.
Call them at the same time. Homeowners who call the plumber, wait for the repair to finish, then start looking for a restoration company lose hours of drying time. Water inside a wall doesn’t pause while you wait for a fitting.
Kiser Construction, over in Elk River, is unusually blunt about this on their own site. They say plainly that they aren’t plumbers and won’t pretend to be. What they handle is everything the water ruined on its way out.
Go find the shutoff tonight
A pipe that froze may already be split. Ice expands hard enough to crack metal, and the crack stays plugged by the ice until it thaws. Then it runs, sometimes behind a wall for hours before anybody notices.
So find your main shutoff now. Not during the emergency.
The boring prevention list
The American Red Cross keeps a short version that covers most of it.
Drain and store the outdoor hoses. Close the inside valve to each hose bib and leave the outside one open, so any trapped water can expand without splitting the pipe. Foam sleeves or UL listed heat cable on anything running through unheated space.
Garage doors shut if water lines run through the garage. Cabinet doors under sinks on exterior walls left open so warm air reaches the plumbing, with the cleaners moved up out of reach first if you’ve got small kids.
Let a cold faucet drip through a deep freeze. Moving water is much harder to freeze than still water.
Same thermostat setting day and night. A higher heating bill for a week is nothing against one repair. And if you’re leaving town in winter, don’t set it below 55.