London rarely gets the deep freezes of northern England, but it only takes a few nights below zero to split a pipe in a loft, garage or under a draughty floor. Most burst pipes we see in winter are in places homeowners never think about until water comes through the ceiling. This checklist takes about an hour to work through and covers the spots that cause the most trouble. Frozen pipes are one of the most common winter call-outs in London.
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Why London homes are vulnerable
A lot of London housing is older: Victorian and Edwardian terraces, 1930s semis and converted flats where pipework has been rerouted over the decades. Pipes often run through unheated lofts, along external walls or under suspended timber floors with an air gap below. Newer flats can be at risk too, especially where pipes pass through communal stairwells, bin stores or unheated cupboards on outside walls.
Water expands by roughly nine per cent when it freezes. In a pipe with nowhere for that pressure to go, the ice forms a plug and the pipe splits, usually between the ice and a closed tap. The damage often only shows when the ice thaws and water starts flowing again.
The 10-point frost checklist
- Find your stopcock and check it turns. It is usually under the kitchen sink, by the front door or under the stairs. If it is stiff, get it looked at before winter.
- Check the loft. Any pipe or cold-water tank in an unheated loft needs proper lagging and a lid on the tank.
- Look under suspended floors if you have access hatches, especially in older terraces.
- Garages and utility rooms on the outside of the house are classic freeze spots.
- Outside taps: isolate them from inside, open the tap to drain it and fit an insulated cover.
- Overflow and condensate pipes running outside can freeze and block. Check they are clear and as short as possible.
- Fix dripping taps. A slow drip can freeze in an exposed pipe.
- Keep some heat on if you go away. A low setting is far cheaper than repairing a flood.
- Open the loft hatch on very cold nights to let a little warm air in, if your tank is up there.
- Save our number somewhere obvious so anyone in the house can call for help quickly.
How to tell if a pipe has frozen
The most common sign is turning on a tap and getting nothing, or just a trickle, on a cold morning while other taps work. You may also see frost on an exposed pipe, or a bulge in it. Toilets that will not refill after flushing often point to a frozen feed pipe in the loft.
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What to do if a pipe freezes
- Turn off the water at the stopcock straight away.
- Open the affected tap so water can escape as it thaws.
- Warm the pipe gently with a hairdryer on a low setting or a hot water bottle, starting from the tap end and working back.
- Never use a blowtorch or any naked flame.
- Check carefully for splits before turning the water back on. If you find one, keep the water off and call a plumber.
When to call a plumber
Call us if a pipe has split, if you cannot find or turn your stopcock, if water is coming through a ceiling or near electrics, or if you would rather have the whole house checked and lagged before the cold sets in. We cover all 33 London boroughs and can usually lag a loft and accessible pipework in a single visit.
Frequently asked questions
How cold does it have to be for pipes to freeze?
Pipes in exposed spots can start to freeze when the air around them stays below 0°C for several hours, especially overnight. Wind and draughts make it happen faster.
Does leaving the heating on stop pipes freezing?
It helps for pipes inside the heated part of the house, but it will not protect pipes in an unheated loft, garage or outside wall. Those need lagging.
Is it worth lagging pipes in a modern flat?
Usually only where pipes run through unheated areas such as communal cupboards or along outside walls. Inside a well-heated flat, the risk is low.
