How to Prevent Frozen Pipes This Winter

Water expands by about nine percent when it freezes. Inside a pipe that creates enormous pressure, and it is enough to split metal.

The damage usually happens when a section freezes solid and forms a plug. Pressure then builds between that plug and a closed tap until the pipe ruptures. Often you do not discover it until the thaw, when it starts flowing.

A burst pipe can release over four hundred litres an hour. That is enough to soak through floors and ceilings, ruin furniture and reach the electrics, which makes it one of the most expensive plumbing emergencies a home can have. Across Crawley, Horsham and the rest of West Sussex and Surrey we get sub-zero spells several times most winters, so a little preparation in the autumn goes a long way.

Which pipes are most at risk

• Outdoor taps and their supply pipes
• Pipes in unheated spaces such as lofts, garages and outbuildings
• Pipes in exterior walls, particularly north-facing ones
• Pipes under kitchen and bathroom sinks against cold outside walls
• Pipes in crawl spaces beneath suspended floors

If you have a condensing boiler, the plastic condensate pipe that runs outside is exposed too. When it freezes the boiler shuts down, which we cover in why a boiler keeps cutting out.

What makes a pipe more likely to freeze

Water freezes at zero, but a pipe usually needs the air around it to drop below about minus six and stay there for several hours before it freezes solid. The risk climbs noticeably once the temperature falls below about minus three, and it depends on several things at once:

• How cold it gets. The lower the temperature, the faster exposed pipes lose heat.
• How long it lasts. A cold snap lasting several days is far more dangerous than a single overnight frost.
• Wind chill. Wind strips heat from exposed pipework much faster.
• Where the pipe runs. Pipes outside, in lofts or in garages freeze long before pipes inside the heated part of the house.
• Insulation. Thin or missing lagging offers very little protection.
• Water movement. Still water freezes faster than moving water.
• Whether the building is heated. Unheated and empty properties are at the highest risk.

The time to act is when the forecast warns of a cold spell, not after the first tap stops running.

Ten things that actually help

1. Insulate the vulnerable pipes. Foam pipe lagging from any DIY shop. Concentrate on lofts, garages and pipes against exterior walls. It costs very little and prevents a great deal.

2. Drain the outdoor taps. Disconnect hoses before winter, close the isolation valve if there is one, and open the outdoor tap to drain what is left. This is the single most common winter burst we attend across Crawley and Horsham.

3. Keep the heating on low. Even when away, hold it at twelve to fifteen degrees. That background heat costs far less than the repair. If you would rather use the timer during a long absence, set it to come on for a few hours twice a day.

4. Open cupboard doors under sinks on exterior walls during a cold snap, so warmer room air can circulate around the pipework. This matters most in kitchens and bathrooms where the plumbing runs along an outside wall.

5. Let taps drip in severe cold. Below about minus six, allow cold taps on exterior walls to drip very slightly. Moving water is much harder to freeze. A trickle is enough.

6. Seal draughts around pipes entering the house, at hose taps, and where pipes pass through into garages. Expanding foam or sealant around the pipe where it comes through the wall deals with most gaps. Leave anything around the boiler flue to a Gas Safe engineer.

7. Insulate the loft properly, ideally 270mm. One important caveat: good loft insulation makes the loft itself colder, so pipes and tanks up there need lagging separately. Never insulate underneath a water tank, because the heat rising from below is what stops it freezing.

8. Service the boiler annually. A well-maintained boiler is far less likely to fail during the cold snap when you need it most. The service picks up developing faults before they become a breakdown in January, and our boiler servicing is from £105.

9. Know where your stopcock is. Make sure everyone in the house knows. Test it now, and if it is stiff or will not turn, get it replaced before winter rather than during an emergency. When a pipe bursts, how quickly you can shut the water off decides how much damage it does.

10. Consider trace heating cable for pipes in genuinely exposed positions that cannot be insulated or moved. It heats automatically when the temperature drops. The cable runs along the pipe itself, which makes it useful for pipework in exposed spots, outbuildings and mobile homes.

The ten methods at a glance

Method	Difficulty	How much it helps
Insulating vulnerable pipes	Easy	High
Draining outdoor taps	Easy	High
Keeping the heating on low	Easy	Very high
Opening cupboard doors	Easy	Medium
Letting taps drip in severe cold	Easy	High
Sealing draughts around pipes	Easy	Medium
Insulating the loft	Moderate	High
Annual boiler service	Engineer job	High
Knowing where the stopcock is	Easy	Limits the damage
Trace heating cable	Moderate	Very high

Most of the easy ones cost little or nothing and can be done in an afternoon. Start there.

Warning signs a pipe is freezing

• Little or no water from a tap even though the system is full
• An odd smell from taps or drains, which is trapped air
• Visible frost on exposed pipework
• Gurgling or banging in the pipes
• A toilet cistern refilling very slowly
• Visible bulging on a section of pipe

Act quickly. A frozen pipe can burst within hours.

If your pipes freeze

1. Turn the water off at the stopcock. This limits the damage if it bursts. Leave the tap open to relieve pressure.

2. Turn the heating up and open cupboard doors to warm the area. If you have caught it early, that alone may be enough to thaw it.

3. Find the frozen section. Look for frost, bulging, or a length of pipe noticeably colder than the rest. It is usually somewhere exposed: the loft, an outside wall or the garage.

4. Apply gentle heat. Towels soaked in warm water, a hot water bottle, or a hairdryer on low. Work from the tap backwards toward the frozen section so meltwater has somewhere to go. Never use a blowtorch or naked flame. High heat can split the pipe and start a fire.

5. Call someone if you cannot find it, cannot reach it safely, or it has already burst. We cover emergency plumbing across Crawley, Horsham, Redhill and the rest of West Sussex and Surrey, seven days a week.

If a pipe bursts

1. Turn off the stopcock immediately
2. Turn off the boiler and heating, if it is safe to reach them
3. Turn off electricity at the consumer unit if water is near electrics. If the consumer unit itself is wet, or you would be standing in water to reach it, do not touch it.
4. Open all taps to drain the system and relieve the pressure
5. Move valuables clear
6. Contain what you can with buckets and towels, and mop up as you go
7. Call an emergency plumber
8. Photograph everything for insurance
9. Contact your insurer once everything is safe

Empty properties

If a property is standing empty over winter, whether a holiday home, a rental between tenancies or your own home during a long trip, it needs more protection than an occupied one:

• Consider draining the system completely. A plumber can drain it down before you leave and refill it when you return, and it is a job we do.
• Use smart heating controls so you can monitor it remotely. A smart thermostat lets you check the temperature and adjust the heating from your phone.
• Arrange weekly checks by a neighbour, a letting agent or someone else local.
• Hold the heating at fifteen degrees minimum, on a timer if you want to keep the cost down.
• Check your insurance, because many policies have specific requirements for unoccupied properties.
• Fit a leak detection system, which sends an alert to your phone if water starts escaping.

Jobs worth booking before winter

Most of the prevention above is DIY. A few jobs are better handed to a plumber before the cold arrives, rather than during it:

• Replacing a stiff or seized stopcock, so it turns when you need it to.
• Lagging pipework you cannot safely reach, such as runs under suspended floors or in awkward corners of the loft.
• Finding a slow leak from pipework that froze and cracked last winter, before it does more damage behind a wall.
• Repairing or replacing pipework that has already split or been patched.