Frozen pipe burst: why it happens, and why thawing fast makes it worse in Solihull

What freezing actually does to a pipe

Water is unusual in that it expands as it turns to ice, by roughly a tenth of its volume. A copper pipe can tolerate a certain amount of that; a plastic push-fit joint tolerates rather less. When the ice plug forms, it also traps water between itself and a closed tap or valve, and that trapped water has nowhere to go as it expands. The pipe splits along its length, usually at a weak point — a soldered elbow, a kinked section, a joint that was already stressed. The split can be a hairline you would miss with a torch.

Where it happens and why

The usual locations are lofts, garages, outbuildings, north-facing wall voids, and any run that crosses a draught from a vent or a letterbox. Outside taps and their supply pipes are top of the list. Pipes freeze fastest where they are unlagged, where they sit against cold masonry, or where a trickle of water is not moving. A property left empty with the heating off in a cold snap is the classic case, but a single cold night with a failed boiler is enough. Older installations with shallow pipe runs under suspended floors are also exposed.

Why the damage gets worse when it thaws

This is the part people miss. While the ice is in place, the pipe may be holding. As it melts, water starts to move again and finds the split, and what looked like a frozen tap becomes water running through a ceiling. Thawing with a blowtorch or a heat gun makes it worse in two ways: it can crack a soldered joint outright, and it releases a lot of water very quickly into a void you cannot see. The safe approach is gradual warmth, starting at the tap end and working back, with the nearest isolator closed and a towel down.

How we diagnose it

We establish which outlets are affected, because that tells us which run is frozen. Then we trace the pipe, check for lagging gaps and draughts, and feel for the cold section. We look for the signs of a split before we thaw: bulging, a green or white crust on copper, damp patches on the pipe's underside, or a faint hiss once pressure returns. Where a run is boxed in we may use a moisture meter rather than opening the whole ceiling. You get a straight answer on whether this is a thaw-and-watch job or a cut-and-replace job.

How we fix it

We isolate and drain where possible, then thaw the run slowly with controlled warm air, working from the outlet back towards the supply so meltwater has somewhere to go. Once flow is restored we pressure-check the section. If it has split, we cut out the damaged length and replace it with new pipe and fittings of the same size, supported and lagged. If the split is at a fitting we replace the fitting rather than trying to solder over a crack. We then check the rest of the exposed run, because frost damage rarely stops at one point.

Reducing the risk next winter

Lag every run in an unheated space, including the short lengths behind a loft hatch that are usually forgotten. Fit isolation valves to outside taps and drain them down in autumn. Keep the heating on a low background setting when the house is empty, and open the loft hatch in severe cold so warm air reaches the tank and pipework. Fix dripping taps before winter, since moving water freezes more slowly but a drip can also indicate a valve that will not shut. If you have been away, run the taps gently on return rather than blasting them open.

When to call us

Call if you have no water at one or more outlets in freezing weather, if you can see a bulged or split pipe, or if water appears as things thaw. A frozen run left to thaw unattended is exactly how a blocked pipe turns into a major pipe failure repair, so if you are unsure, ask. If a pipe has already let go, close the stopcock and open the cold taps — that is emergency pipe repair, not a maintenance visit. We run a pipe thawing service for occupied homes that have lost supply but not yet burst, and our emergency plumber burst pipe cover runs through cold nights. If you are looking for a burst pipe plumber near me at eleven at night, ring the office number rather than a comparison site; you will get a person who can tell you what to do in the next ten minutes.

Book a call-out

Book online for a planned thaw and lag, or ring if water is already moving. Either way, tell us the property type and where the affected outlets are — it saves time on arrival and it helps us bring the right fittings.