How to Stop Pipes Freezing in Winter

The best way to stop pipes freezing is to lag exposed pipes, keep your heating on at a low setting during cold snaps, and protect outside taps before the first frost. If a pipe does freeze, turn off the water at the stopcock, thaw it slowly with gentle heat and never use a naked flame. If a pipe has split or you cannot find the frozen section, call a plumber.

Why pipes freeze and burst

Water expands as it freezes, building pressure that can split pipes or push joints apart. Often you only notice when the ice melts and water starts to leak.

The pipes most at risk are those in cold, unheated spaces: lofts, garages, outbuildings, under suspended floors, against outside walls and anything running outdoors.

Prevention checklist before winter

Most of these jobs take an afternoon and cost very little.

Find your stopcock and check it turns. It is usually under the kitchen sink, but can be in a cupboard, under the stairs or under a floor. If it is stiff or seized, get it looked at now, not during an emergency.

Lag exposed pipes in the loft, garage and under floors (see below).

Insulate the cold water tank in the loft if you have one, but leave the area directly beneath it uninsulated so some warmth from the house can rise to it.

Protect outside taps. Turn off the internal isolation valve if there is one, open the outside tap to drain it, then fit an insulated tap cover.

Check your boiler’s condensate pipe if it runs outside (more on this below).

Service your boiler. A boiler that is working well is less likely to let you down in a cold snap. See our guide to booking a boiler service.

Lagging pipes

Lagging insulates pipes so they lose heat more slowly. It will not stop freezing in a long hard frost with no heat at all, but it buys a lot of time.

Foam pipe lagging is the easiest option. It comes in tubes with a slit down the side, sized to your pipe diameter (15mm and 22mm are the most common in homes). Push it over the pipe and seal the joints with tape.

Cover bends and valves with lagging cut to fit, or wrap them with insulation tape. Gaps are where freezing often starts.

Leave access to stopcocks and valves so you can still turn them off.

Foam lagging is cheap and sold in most DIY stores. If pipes are hard to reach, a plumber can do it.

Keep the heating on during cold snaps

When temperatures drop well below freezing, keeping the heating on at a low temperature is one of the most effective ways to stop pipes freezing inside the house.

Set the heating to come on for longer periods, or use the boiler’s frost protection setting if it has one.

If you are going away in winter, leave the heating on at a low setting rather than off. Many home insurers set conditions about this, so check your policy.

Open the loft hatch on very cold nights to let some warm air reach pipes and tanks in the loft.

Frozen pipes: what to do

Signs of a frozen pipe include no water from a tap, a toilet that will not refill, or frost visible on a pipe.

Turn off the water at the stopcock. This limits the damage if the pipe has split.

Open the tap fed by the frozen pipe so water can flow out as it thaws.

Find the frozen section. It is usually the coldest, most exposed part of the pipe.

Thaw it gently. Use a hot water bottle, warm cloths or a hairdryer on a low setting, starting from the tap end and working back.

Never use a blowtorch or any naked flame. It is a serious fire risk and can damage pipes and joints.

Check for leaks as the pipe thaws. If you see water, keep the stopcock off.

If water is leaking near electrics, switch off at the consumer unit only if it is safe and dry to reach, and do not touch wet fittings.

If a pipe has burst

Turn off the stopcock, switch off the boiler or immersion heater, and open the cold taps to drain the system. Call a plumber. Our guide on what to do when a pipe bursts covers the first 30 minutes step by step. If water is pouring through a ceiling out of hours, contact emergency plumbers in Reading.

Frozen condensate pipe

Modern condensing boilers produce acidic water that drains away through a plastic condensate pipe. When that pipe runs outside, it can freeze in very cold weather. The boiler then detects the blockage and shuts down, often showing a fault code and making a gurgling noise.

To thaw a frozen condensate pipe:

Find the pipe. It is usually white or grey plastic, running from the bottom of the boiler through an outside wall to a drain.

Apply warmth to the frozen section, usually at the end or a bend. Hold a hot water bottle or heat pad against it, or pour warm (not boiling) water slowly over the frozen section. Boiling water can crack the pipe.

Restart the boiler using the reset button once the pipe has cleared, following the manufacturer’s instructions.

Only do this for pipework you can safely reach from the ground. Do not climb ladders in icy conditions, and avoid pouring water where it will refreeze on paths. Do not open the boiler casing or touch any gas parts. If the boiler still will not restart, or the pipe is high up, call a Gas Safe registered engineer.

If your condensate pipe freezes regularly, a Gas Safe engineer can reroute it internally where possible, increase the pipe size outside, or add insulation or trace heating.

When a plumber is needed

Call a plumber if:

A pipe has split, burst or is leaking

You cannot find or reach the frozen section

The stopcock is seized or will not turn off fully

Pipes keep freezing in the same place every winter

Anything involving gas appliances, including boilers, needs a Gas Safe registered engineer. Do not attempt it yourself.

Job

Typical UK range

Notes

Emergency call-out for a burst pipe

£100 – £250

Out-of-hours costs more; labour and parts usually extra

Repair an accessible burst pipe

£100 – £300

More if pipes are under floors or in walls

Replace a seized stopcock

£100 – £250

Depends on access and pipe type

Lag pipes in a loft or under floors

£80 – £250

Depends on how much pipework and access

Reroute or upgrade a condensate pipe

£100 – £350

Must be done by a Gas Safe engineer

These are typical ranges, not fixed prices. Costs vary with access, materials and how urgent the job is.

Getting quotes

For non-urgent work such as lagging, replacing a stopcock or rerouting vulnerable pipes, it is worth getting three quotes before the cold weather arrives.

Brief the job clearly. Say which pipes are affected, where they run and whether they have frozen before. Photos help.

Ask whether the price is fixed or hourly, what is included, and whether parts and VAT are extra.

Compare three quotes so you can see a fair middle price and spot anything much higher or lower.

To find someone ahead of winter, compare local plumbers in Reading.

FAQs

How do I stop pipes freezing?

Lag exposed pipes, insulate the loft tank, protect outside taps and keep your heating on low during cold snaps, including when you are away.

Frozen pipes: what should I do first?

Turn off the water at the stopcock, open the affected tap, and thaw the pipe gently with a hot water bottle or a hairdryer on low. Never use a naked flame.

How do I fix a frozen condensate pipe?

Warm the frozen section with a hot water bottle or warm (not boiling) water, then reset the boiler. If the pipe is out of reach or the boiler will not restart, call a Gas Safe engineer.

Is lagging pipes worth it?

Yes. Foam lagging is cheap, quick to fit and slows heat loss from pipes in cold spaces, which reduces the risk of freezing.

Get up to 3 quotes from vetted local plumbers. Tell us about the job and your postcode, and we’ll match you with trades whose reviews come from real, invoiced jobs.