Pipe lagging: the winter job that costs pennies and prevents floods

The pipes most likely to freeze are the ones you can see: loft runs, garage and outbuilding feeds, and everything outdoors. Water sits still in a cold snap, the pipe in an unheated space hits freezing, and the ice quietly blocks the line until the pressure between blockage and tap splits it somewhere else - the whole failure chain is in the frozen-pipe guide. Lagging is the prevention, it costs a few pounds a run, and an October afternoon finishes the whole house.

The job

Clamp-on foam sleeves come in diameters to match copper and plastic pipe; cut to length with scissors and slip them on, sealing the longitudinal seam and the joints with lagging tape. Cover the full run in unheated spaces - the loft run from tank to bathroom, the garage feed, anything within a foot of an external wall or vent. bends and elbows get cut sleeves or tape wraps; a corner left bare is the weak link. While you are up there: check the loft hatch, tank insulation and any draughts blowing across pipes - moving cold air freezes pipes faster than still cold, the same air-sealing logic as the draught guide.

The outside jobs

The outdoor tap gets an insulated tap jacket - a pound or two - and its indoor shut-off gets identified so the line can be drained before a hard freeze. Any exposed waste pipes and the boiler's condensate run (a modern boiler essential) get the same sleeves; a frozen condensate pipe is the most common winter boiler stoppage of all, with its own fix in the condensate guide.

The honest limits

Lagging slows heat loss; it cannot heat a pipe. A pipe in a genuinely freezing loft needs the loft warmer (more insulation under it, less draught over it) or a trace-heating cable on the worst runs. And lagging is the second line of defence after knowing where the stopcock is - the shut-off walkthrough is the ten-minute read that pays for every winter job on this page. Fold the whole afternoon into the autumn checklist and the pipes go into every winter bored and ready.