Quick Answer:
If the valve will not move during a cold snap, stop forcing it. Warm pipe gradually with hair dryer until the valve can be turned, then fully thaw and insulate after thaw to prevent a repeat. If you cannot free the valve or it looks damaged, call a plumber.
Why This Happens
- Cold temperatures can freeze water sitting in or around the valve and nearby pipe, locking the mechanism.
- Poor insulation or an exposed main line near exterior walls, crawlspaces, or basements increases the risk of freezing.
- Older valves can seize from corrosion and mineral buildup, which becomes worse when water inside freezes and expands.
Step-by-Step What to Do
1. Stop and assess
- Do not force the handle. Excess force can break the valve or the pipe.
- Locate the shutoff and check whether it is exposed to cold air or behind a wall. If you suspect it’s behind drywall, see information about shutoff behind finished wall before making holes.
2. Clear the area
- Move rugs, cardboard, or anything combustible away from the valve and pipes.
- Set up a safe, dry spot for tools and a bucket for any drips once thawed.
3. Warm the pipe gradually with hair dryer
- Plug the hair dryer into a dry outlet and keep it at least a few inches from the pipe and valve.
- Move the heat slowly along the pipe toward the valve. Do not concentrate heat on one spot for too long.
- As the metal warms, periodically try to turn the valve gently. If it begins to move, stop and continue warming until it turns smoothly.
4. Turn the valve and check for damage
- Once the valve moves, turn it slowly to avoid a sudden surge of water pressure.
- Inspect the valve and nearby pipe for cracks or leaks. If you see damage, shut the water off only if you can do so without forcing the valve, then call a plumber.
5. Insulate after thaw
- After everything is thawed and dry, insulate exposed pipe and the valve with foam sleeves or pipe wrap to reduce future freezing risk.
- Consider adding heat tape in very cold areas and sealing drafts around access panels.
What Not to Do
- Do not use open flame to thaw a frozen pipe or valve — this can ignite nearby materials and damage the pipe.
- Do not pour boiling water directly onto pipes; rapid temperature change can crack solder joints or brittle piping.
- Do not force a stuck valve; broken valve hardware or a snapped pipe can lead to a much larger emergency.
When to Call a Professional
- If the valve remains stuck after gradual warming and careful attempts, call a licensed plumber.
- If you find cracks, active leaks, or joint failure when thawing, shut down water only if safe and call a pro.
- If the main shutoff is not easily accessible—such as when it is hidden behind finished walls—get professional help rather than opening walls yourself; for guidance, see the note about shutoff won’t turn.
Safety Notes
- Avoid electrical hazards: keep the hair dryer and extension cords away from water and wet surfaces.
- Warm slowly and keep heat sources moving to prevent hot spots and damage to pipes or finishes.
- If you smell gas or suspect a gas appliance is involved, evacuate and contact emergency services immediately before doing any work.
Common Homeowner Questions
- My valve is slightly loose after thawing — can I leave it?
Short answer: No. Have a plumber inspect and replace any worn or leaking valve to avoid failure. - Will insulation alone stop this from happening again?
Short answer: It helps a lot, but combine insulation with sealing drafts and, in very cold areas, heat tape for best protection. - Can I replace the main shutoff myself?
Short answer: Only if you have plumbing experience; otherwise hire a pro because replacing a main shutoff often requires shutting off the water from the street or coordinating with your utility.