How do I stop pipes freezing?

Water expands as it freezes, and a sealed pipe has nowhere to give — which is why frozen pipes burst. The damage usually appears when it thaws, not when it freezes, so a pipe that froze overnight can flood the house the following afternoon.

Safety

What you'll need

• Foam pipe lagging
• Outside tap cover
• Insulation tape
• Hot water bottle or hairdryer for thawing (optional)

Step by step

1. Identify pipes in unheated spaces: loft, garage, outbuildings, and against external walls.These are the ones that freeze. Pipes inside heated rooms rarely do.
2. Fit foam lagging to every exposed pipe, including the elbows and joints.Joints and bends are usually left bare and are exactly where freezing starts. Split lagging pushes on easily; tape the seams.
3. Insulate the cold water tank in the loft, but leave the area beneath it uninsulated.Heat rising from the house below is what keeps the tank from freezing. Insulating under it removes that.
4. Fit an insulated cover to the outside tap, and isolate and drain it if you can.Outside taps are the single most common burst point.
5. Keep background heat on in very cold weather, even when away.A frost-protection setting of around 5–7°C costs far less than a burst pipe.
6. Open the loft hatch during a severe freeze.It lets warm air reach the loft pipework. Counterintuitive but effective in a hard frost.
7. If you're away for a long period in winter, consider draining the system.Turn off at the stopcock and open the taps to drain down. Worth it for extended absences.
8. If a pipe has frozen, turn off the stopcock, then thaw gently from the tap end backwards.Hot water bottle, warm towels or a hairdryer on low. Never a flame. Working from the tap end gives the melt somewhere to go.

Tips

• Know where your stopcock is and check it turns before winter. A frozen pipe is not the moment to discover it's seized.
• A dripping tap in a hard frost keeps water moving and reduces freezing risk in a vulnerable run — a small waste against a large risk.
• Check pipes in a garage or outbuilding that has been converted — insulation is often missing where a space changed use.
• If you find a burst, turn off the water first and the electricity second if water is anywhere near fittings.

Common mistakes

• Using a blowtorch or heat gun to thaw a pipe — Fire risk, and rapid heating can split the pipe. Gentle heat only.
• Insulating underneath a loft tank — It blocks the rising heat that keeps the tank above freezing.
• Turning the heating fully off when away in winter — A burst pipe costs vastly more than a few weeks of frost protection.
• Thawing before turning off the stopcock — If the pipe has already split, thawing it releases mains water into the house.

Questions people ask