Frozen pipes: how to thaw them and prevent a burst
Quick answer
If a faucet barely trickles during a freeze, a pipe is likely frozen. Open that faucet so water can flow as the ice melts, find the frozen section (usually along an exterior wall or in an unheated crawlspace, garage, or attic), and apply gentle heat with a hair dryer, heat lamp, or warm towels — never an open flame. If a pipe has already burst, shut off your water main immediately. Prevent freezing by keeping the heat on, letting faucets drip in extreme cold, opening cabinet doors, and insulating exposed pipes.
Common causes
- Pipes in unheated or poorly insulated spaces — crawlspaces, attics, garages, and exterior walls.
- A hard drop below freezing, especially with wind exposure.
- Setting the thermostat too low (or off) while away.
- Missing pipe insulation or heat tape on vulnerable runs.
What to check first
- Open the affected faucet so water and steam can escape as the pipe thaws.
- Locate the frozen section — look for frost, bulging, or pipe that's ice-cold to the touch, near exterior walls.
- Apply gentle heat starting near the faucet and working back toward the frozen area.
- Never use a blowtorch or open flame — it's a fire risk and can damage pipes.
- Know where your main water shutoff is, in case a pipe has already split.
When it's urgent
A burst or split pipe — often discovered as it thaws and water starts flowing out — is urgent: shut off the water main immediately and call a plumber, because even a small split can flood a room fast. In a hard cold snap, unprotected pipes can burst with little warning, so act on the early trickle before it becomes a break.
DIY vs. call a pro
You can likely DIY
- Thawing an accessible pipe with gentle heat.
- Dripping faucets and opening cabinet doors in extreme cold.
- Insulating exposed pipes and knowing the main shutoff.
Call a pro for
- A burst pipe and the resulting water cleanup.
- Pipes you can't reach (inside walls or a slab).
- Re-piping or adding permanent freeze protection.
Estimated cost range
How HouseCue helps
HouseCue is a private, homeowner-first app that turns this from a one-time worry into a tracked plan. Snap a photo for an AI diagnosis, upload your inspection report to auto-build a handbook, and get seasonal reminders for your roof, HVAC, water heater, plumbing, and electrical — so nothing slips. Connecting with a pro is always optional and only when you choose.
Get started freeFrequently asked questions
How do I thaw a frozen pipe?
Open the faucet the pipe feeds, then apply gentle heat — a hair dryer, heat lamp, or warm towels — starting near the faucet and moving toward the frozen spot. Never use an open flame. If you can't reach the pipe or it has burst, shut off the main and call a plumber.
How do I keep pipes from freezing?
Keep the home heated (even when away), let faucets drip during extreme cold, open cabinet doors so warm air reaches pipes on exterior walls, and insulate or add heat tape to exposed pipes in crawlspaces, garages, and attics.
Will frozen pipes always burst?
Not always, but frozen water expands and the pressure can split a pipe — and the leak often appears once it thaws. The risk is real enough that you should thaw a frozen pipe promptly and know where your main shutoff is.
Related guides
HouseCue guides are general educational information, not professional inspection, engineering, or contracting advice. Costs vary by market. For safety issues — gas, electrical, structural, or major water — contact a qualified professional.