Quick Answer:
If you hear banging only in cold months, it’s often pipes moving as they contract in low temperatures or a support that’s gone loose. If the noisy run is in a crawlspace or an exterior wall, a plumber can inspect the run and recommend safe insulation or better supports to stop the contact noise and reduce freeze risk.
Why This Happens
- Cold metal and plastic pipes contract as temperatures drop. That movement can make a pipe hit wood framing or hangers, creating a banging sound.
- Pipes in exterior walls or crawlspaces feel bigger temperature swings, so the noise is more likely there than in heated interior walls.
- On very cold days the contraction is greater and the banging is often more frequent.
- Occasionally a partial freeze or trapped water can change flow and pressure, which can also make loud noises when valves are used.
Step-by-Step What to Do
1. Locate the noisy run
Walk the house while the noise is happening. Focus on exterior walls, basement ceilings, and crawlspaces. Identify which fixtures (bathroom, kitchen, outdoor hose) are on the same run so you can target the correct section.
2. Compare noise on very cold days
Note whether the banging increases on extremely cold days. A clear pattern tied to outdoor temperature points to thermal contraction rather than a loose fitting inside the heated part of the house.
3. Run warm water briefly, then shut it off
Open a hot tap for a short time and then shut it. If the noise changes or stops, the issue may be related to temperature changes in the pipe or water pressure shifts. This is a simple diagnostic to see if heat or flow affects the banging.
4. Inspect pipe supports and penetrations
Where pipes pass through framing, look for loose straps, worn insulation, or gaps that let the pipe move and strike wood. Tighten loose straps or add a small pad around the pipe where it rubs. If the run is inside an exterior wall or hard to reach area, document the location for a plumber.
5. Check nearby appliances and history
If the noise appeared after work on the water system or after the water heater was refilled, that context helps diagnose the cause. Also consider related situations like nighttime-only sounds — see Pipes bang only at night and if it followed a water heater refill check Hammer noise after water heater refill.
What Not to Do
- Don’t use an open flame, propane torch, or any unapproved heater directly on or near pipes.
- Don’t apply aggressive heat to a suspected partially frozen line — this can crack fittings or cause burns and fire risk.
- If you suspect a partially frozen line or cannot safely access the run, contact a plumber instead of trying risky repairs yourself.
When to Call a Professional
- If you find frost, bulging pipe sections, or any sign of a freeze that might lead to a burst.
- If the noisy run is in an exterior wall or crawlspace and you can’t safely access it — a plumber can recommend safe insulation and secure supports.
- If loose straps, repeated banging, or pressure-related noises continue after simple fixes, call a plumber to inspect for pressure issues or failing supports.
Safety Notes
- Avoid open flames and unapproved heating methods around plumbing and building materials.
- If a pipe bursts, shut off the main water valve and call a plumber immediately.
- When using space heaters in unheated areas, ensure proper ventilation and keep them away from combustibles. Never leave heaters unattended.
Common Homeowner Questions
- Will the banging stop when it warms up? — Often yes; thermal contraction is the usual cause and it typically quiets when temperatures rise.
- Can I fix it by myself? — You can tighten visible loose straps or add simple insulation if accessible, but call a plumber for exterior wall runs or suspected freeze risk.
- Is it an emergency? — Not usually, but treat signs of freezing, leaks, or bulging as urgent and contact a professional right away.
For more related articles, see the Pipes Banging After Fixtures Turn Off hub.