Frozen pipes: the winter checklist that prevents the burst

A frozen pipe is a delayed flood. The ice itself does not usually burst the pipe at the freeze point - it blocks the line, and the pressure between the blockage and the closed tap splits it somewhere else. Which is why prevention, done before the first hard freeze, is the entire game.

Before winter: the prep list

Insulate the vulnerable runs. Pipes in unheated spaces - crawlspaces, garages, exterior walls, that one freezing utility cupboard - are the candidates. Foam pipe sleeves are cheap and cut with scissors.

Seal the drafts. Cold air moving over a pipe freezes it faster than cold air sitting still - the same physics the attic checklist uses: air-sealing pays everywhere.

Drain and disconnect outdoors. Garden taps and their hoses: hose off, tap drained if it has an internal shut-off. Water left in an exterior line is the classic split.

Know the main shutoff cold. If a pipe ever bursts, the first sixty seconds are the shut-off valve and nothing else - locate it and test it today, not in an emergency.

During a hard freeze

Let the vulnerable taps drip slowly - moving water is far harder to freeze, and a running tap costs pennies against a plumber's emergency call. Open the cupboard doors under sinks on outside walls so room warmth reaches the pipes. Keep the home heated even when away - a thermostat set lower, never off, in cold snaps: the setback guidance caps out before "off" does.

If a pipe freezes - or bursts

Frozen but intact: shut-off off at the main for safety, then thaw gently along the pipe - warm (not boiling) cloths, a hairdryer on low, working from the tap backwards. Never an open flame or a blast furnace heat gun; steam inside a pipe is its own explosion. Burst: main off, taps open to drain pressure, towels and buckets, then the repair call - and dry the space fast, because the clock on mould starts immediately. Any water near electrics means the electrics win: power off first, and treat any after-damp socket with suspicion. The autumn checklist slots this in before the first freeze each year - the cheapest insurance policy in the house.