Frozen Pipe London — Emergency Thawing & Repair

First, turn off the water at the stopcock. This means that if the pipe thaws and has cracked, water won't flood your property. Then check whether the pipe has already burst: look for water stains, sagging ceilings or wet walls near the pipe. If you can see the frozen section and it's accessible copper or plastic pipework, you can apply gentle heat (warm towels or a low-temperature hair dryer on the coolest setting). Never use a blow torch or boiling water on frozen pipes, as thermal shock cracks the metal. Call us if the pipe is in an inaccessible location (under floors, in walls, in loft) or if you suspect it has already burst.

In London, the pipes most vulnerable to freezing are: the condensate pipe on combi boilers (runs outside or through an unheated garage); loft tank supply pipes (cold water storage tanks in uninsulated lofts); pipes running through unheated outbuildings or garages; external garden tap supply pipes; pipes in external walls with poor cavity insulation; and pipes in poorly insulated ground-floor kitchen units against external walls. London has relatively mild winters, but when temperatures fall below -5°C (which happens several times per decade), exposed pipes freeze rapidly.

The condensate pipe is usually a 22mm white plastic pipe that exits through the wall and terminates outside. To thaw it: pour warm (not boiling) water over the external section, or wrap warm wet towels around it. Once thawed, the boiler may need resetting (hold the reset button for 3 to 5 seconds). If the boiler shows an EA or similar lockout code and won't reset after thawing, call us, as there may be a secondary fault. To prevent refreezing, insulate the external section with foam pipe lagging from any hardware store.

Thawing an accessible frozen pipe costs £80 to £180 (1 to 2 hours labour). If the pipe has burst during freezing, repair costs depend on the pipe location and material: a short copper section repair costs £120 to £250; a lead pipe section (common in older London terraces) replacement costs £200 to £500+; pipes under concrete floors or in walls (trace and access) can cost £300 to £800+ for the access work alone. We give a fixed quote before starting work. The £60 call-out is waived on jobs over 2 hours.

The most effective prevention measures: insulate exposed pipes in lofts, garages and external walls with foam lagging (minimum 25mm); keep heating on a minimum 12°C when the property is unoccupied in winter; ensure your loft is insulated (reduces loft air temperature fluctuations); lag your boiler condensate pipe where it runs through unheated areas; drain garden taps and shut off their supply valves in October; and service your boiler annually. A boiler in good condition is less likely to lock out in cold weather, which is when condensate pipes freeze most. Properties going unoccupied for extended periods should be drained down completely.

Yes, and that is when most people find out. Ice expands and can split a copper pipe or push a joint apart while it is frozen, but the ice also plugs the split, so nothing leaks until it melts. Turn off the stopcock before you thaw a pipe, then turn it back on slowly and watch the frozen section for drips. If water appears on a ceiling or wall as the weather warms up, turn the stopcock off and call us.

Pipe freezing is a technique where a plumber clamps a freezing kit around a pipe to create a temporary ice plug. It lets a valve, stopcock or fitting beyond the plug be replaced without draining the heating system or shutting off water to a whole building. It is often used in flats with a shared or missing stopcock. It only works on a pipe with no water flowing through it.