Plumbing advice for Dumbarton homes
Frozen pipes: how to prevent them and what to do if one bursts
A frozen pipe does its damage in two stages. The frost splits it quietly in the night. Then the thaw arrives and the split pipe begins to pour.
That is why burst pipes so often show up on the mild day after a cold snap. A little work in autumn stops most of them.
Which pipes freeze
Water freezes in pipes that are cold, still and unlagged. In a normal house that means a short list.
- Pipes and tanks in the loft, above the insulation
- Pipes in a garage, outhouse or unheated porch
- Pipes under a suspended timber floor with air bricks
- The pipe to an outside tap
- Pipes in a cupboard on an outside wall
- The plastic condensate pipe from a modern boiler, where it runs outdoors
- Any pipe in a home left empty and unheated
Loft insulation makes the rooms warmer and the loft colder. If your loft has been topped up in recent years, the pipes and tank up there are more at risk than they used to be, not less.
Before the cold: an autumn checklist
- Fit foam lagging to every pipe you can reach in the loft, garage and under the floor. Tape the joints so no bare copper shows.
- Check the loft tank has a jacket and a lid. Leave the loft floor under the tank bare of insulation so a little warmth rises to it.
- Shut off the outside tap at its indoor valve and open the tap to drain it.
- Fix dripping taps and overflows. A trickle into a cold waste pipe freezes layer on layer until the pipe is blocked with ice.
- Find your stop valve and make sure it turns. See finding your stop valve.
- Have the boiler serviced by a Gas Safe registered engineer, so the heating does not fail in the first hard frost.
During a cold snap
Keep the heating on low through the night and when you are out. A steady background warmth is cheaper than a burst.
Open the loft hatch on the coldest nights to let some heat up. Open the doors of sink cupboards on outside walls.
Going away? Do not switch the heating off. Set it to come on for a spell each day, or leave the thermostat at a low setting. Ask a neighbour to look in. For a long absence in winter, a plumber can drain the system down.
How to tell a pipe has frozen
You turn on a tap and get a trickle or nothing. The toilet cistern does not refill. The boiler shows a fault and will not fire, which often means the condensate pipe has iced up.
Check with a neighbour first. If they have no water, the problem is in the street and is one for Scottish Water. If they have water and you do not, the freeze is on your side.
Thawing a frozen pipe safely
- Turn off the water at the stop valve. If the pipe has split, you will not know until it thaws.
- Open the tap nearest the frozen section so melting water can escape.
- Find the frozen part. It is usually the coldest, most exposed length, and may have frost on it or a slight bulge.
- Warm it gently, working from the tap end back towards the frozen part. Use a hot water bottle, towels soaked in hot water, or a hair dryer on a low setting.
- Never use a blowlamp, a heat gun or a naked flame. Pipes burst, joints melt and houses catch fire.
- For a frozen condensate pipe, pour warm water, not boiling, over the outside length, then reset the boiler.
When it has thawed, turn the stop valve on slowly with someone watching the pipe. If water sprays or drips, shut the valve again.
If the pipe has burst
Shut the stop valve. Open the cold taps to drain the system. Turn off the heating and any immersion heater. If water is near electrics, switch off at the main switch if you can reach it safely.
Then get a plumber. Checkatrade's water pipe repair guide puts a plain burst pipe repair at £220 to £440, with emergency call-out charges on top if it cannot wait. Our emergency plumber page has the first steps and the form with the urgent switch.
Take photographs for your insurer before you clear up, and move what you can out of the wet.
Why this matters in Dumbarton
Most of the town sits low beside the Clyde and the Leven. Bellsmyre is the exception, on the edge of the Kilpatrick Hills, and higher ground is the first to feel a frost.
Homes with a cold tank and pipes in the loft are the classic frozen pipe houses, and post-war estates were commonly plumbed that way. If yours is one, the loft is the first place to lag.
Lag it in October, not January
Frost protection only works if it is in place before the frost. Once the forecast turns, every plumber within reach of Dumbarton is busy with bursts, and the simple jobs have to wait. An hour of lagging and a working stop valve cost little. A burst in the loft can bring down a ceiling.
Say what needs protecting or repairing and where in Dumbarton you are. You pay nothing for asking.