Key takeaways
- Pipes in exterior walls, garages, crawl spaces and attics freeze first.
- Disconnect garden hoses and protect outdoor faucets before the first hard freeze.
- Insulation slows freezing but does not stop it in a deep cold snap.
- Never use an open flame to thaw a pipe.
- If a pipe splits, shut off the main water valve and call a plumber.
Where pipes are vulnerable
Water expands as it freezes, and that expansion is what splits a pipe, often well away from the ice itself. In Ohio the risk is greatest where plumbing runs through cold, unheated space or close to the outside.
Check these spots first:
- Pipes in exterior walls, especially on the north side of the house and in kitchens or baths with a sink on an outside wall
- Supply lines in unheated garages, attached porches and breezeways
- Plumbing in crawl spaces and the rim area of the basement, where pipes sit close to the foundation
- Pipes in attics and over unheated additions
- Outdoor hose bibs and irrigation lines
Older houses are often at higher risk because insulation may be thin or missing and pipes were sometimes run through walls that were later left uninsulated. Houses with an open gap around a cable, dryer vent or other penetration can pull in a surprising amount of cold air right next to a pipe.
Hose bibs and outdoor plumbing
Outdoor faucets are the most common freeze failures, and the damage is often hidden. A hose left attached traps water in the faucet and in the pipe behind it. When that water freezes, the split may be inside the wall, and you will not know until the faucet is turned on in spring and water sprays into the house.
In the fall, disconnect every hose, splitter and timer. If your faucet has an interior shutoff valve, close it and open the outdoor faucet to let the line drain. Frost-proof faucets are designed with a long stem so the shutoff sits inside the warm part of the house, but they only work when the hose is removed and the faucet is installed with a slight downward pitch so it can drain. A faucet that drips from the spout after the handle is closed may be failing.
If you have a lawn irrigation system, it needs to be drained or blown out before winter. That is a job for the company that services your system or a plumber, since compressed air used incorrectly can damage the lines.
Insulation, heat and dripping faucets
Foam pipe sleeves are inexpensive, easy to fit and worth installing on any exposed hot and cold lines in unheated areas. Seal gaps in the rim area and around penetrations with caulk or foam so cold air is not blowing across the pipe. Insulation slows heat loss but cannot create heat, so a pipe in an unheated space can still freeze in a long cold snap.
Heat cable, sometimes called heat tape, can add protection for a pipe that is known to be exposed. Use only a product rated for your pipe material and location, follow the manufacturer's instructions exactly, and replace anything that is frayed or damaged. Improper use is a fire risk.
During a hard freeze:
- Keep the thermostat set steady, and do not drop it far when you travel
- Open cabinet doors under sinks on exterior walls so room air reaches the pipes
- Let a faucet at the end of a vulnerable line run at a thin, steady trickle of cold water. Moving water is harder to freeze, and a split pipe will not build pressure against an open faucet
- Keep the garage door closed
If you will be away, ask someone to check the house, or have a plumber shut off and drain the system.
What to do if a pipe freezes
The first sign is usually a faucet that gives only a trickle or nothing at all. If the cold weather is the obvious cause, act quickly, because a frozen pipe can split as it thaws.
- Leave the affected faucet open. Water needs somewhere to go as the ice melts.
- Find the frozen section. It is often on an exterior wall or near a crawl space entry, and the pipe may feel very cold or show frost.
- Warm it slowly with a hair dryer, a heating pad or warm towels. Start at the faucet end and work back toward the blockage.
- Never use a propane torch, open flame, or space heater left unattended near the pipe. These are fire hazards and can damage the pipe.
- Once water flows normally, check the pipe and fittings for leaks.
If you cannot reach the frozen section, if it is inside a wall or under a floor, or if you see water leaking, call a plumber. If a pipe has already split, shut off the main water valve immediately. Open faucets to drain the lines, and keep water away from electrical outlets and appliances. A plumber can repair the break and check other pipes that went through the same cold. For leaks that need repair, see our leak repair service.
After the cold passes
A pipe can crack without bursting, leaving a slow leak that appears days later. After a hard freeze, check basements, crawl spaces and the walls under sinks for dampness, and watch your water meter for movement when nothing is running. Our guide to finding hidden leaks explains how.
If a pipe froze once, it will probably freeze again. Note where it happened, and ask a plumber about rerouting the line, adding insulation inside the wall, or closing an air gap. Questions about your own situation are welcome through our contact page.
Frequently asked questions
At what temperature do pipes freeze?
Water freezes at 32 degrees, but pipes in unheated spaces can freeze when outdoor temperatures stay low for a long stretch, and wind makes it worse. Pipes in exterior walls and crawl spaces are at risk well before the house itself feels cold.
Should I let my faucets drip in winter?
During a hard freeze, a thin steady trickle of cold water at a faucet on a vulnerable line helps prevent freezing and relieves pressure if ice forms. It is not needed every night of winter.
Can I thaw a frozen pipe myself?
If the pipe is accessible, you can warm it slowly with a hair dryer or heating pad with the faucet open. Never use an open flame, and call a plumber if the pipe is inside a wall or you see any leak.
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