Has any of you knowlegable folks out there got any advice on avoiding
burst water pipes during the big freeze (if we get one) this winter?
It`s never happened to me but I bet anyone that has suffered the
results of a burst pipe wishes they had taken measures to avoid it.
Lag all pipes, especially those in cold loft or underfloor spaces. Don't
turn the heating off when not there, just set it to a low temperature
instead. Turn off outside tap at isolating valves inside the house. Then
open the outside tap.
If going for some time, turn off the rising main. Drain the hot/cold water
system. This will limit the extent of any flood (unless it is on the supply
On the slightly more work front, always use plastic pipes in loft spaces.
When insulating the loft, insulate the rafters rather than the floor for a
warm loft situation that keeps pipes and tanks from being cold.
Warm lofts have often confused me - surely, as you have to keep the eves
clear to allow air movement, then insulating the rafters (the main bit of
the roof where the tiles are?) would result in warm air being up in the
loft, but being blown out with draughts etc.
What stops that happening?
Building Regs require ventilation in order to prevent condensation on roof
timbers. This will only form on timber surfaces which are colder than the
heated spaces in the building (those not fully enclosed by the roof insulation)
so it follows that ventilation is only required on the cold side of the
insulation. In roofs where the insulation is laid horizontally on the ceiling
joists, the whole roofspace will be cold and needs to be ventilated. If the
insulation is fixed under the rafters, only the rafters will be cold and so
ventilation is only required to the voids between them, on the cold side of the
insulation. This void needs to be a minimum of 50mm deep to maintain sufficient
You'll hear people talking about a "warm roof" not requiring any ventilation.
This is confusing. A warm roof is where ALL the roof timbers are on the warm
side of the insulation, where the insulation is laid over the top of the
rafters. (Tiling battens don't count). In this case no ventilation is
necessary as condensation will not form on the timbers.
Ignore PJO Tony, I think this is a very sensible and timely question. I just
want to add a couple of points to Christian's advice:
Remember pipe and tank lagging does not give 100% protection. Luckily I was
around at the time so there was no damage, but our pipes in the loft froze one
winter, even though they were properly lagged. It was due to icy cold wind
blowing through the roof tiles, as we have no sarking felt under the roof
tiling. This only happened in one place where the pipes are close to the tiling
and I got over it by shielding the pipes and the tanks from the draught with a
couple of old blankets pinned to the underside of the rafters. This sort of
thing can also happen near airbricks and other ventilation openings.
The principle of pipe lagging is that it slows down the rate of heat loss from
pipes and tanks. It doesn't prevent freezing when there is no heat to start
with. So if you leave the house unheated for long enough, the lagged pipes and
tanks will still be liable to freeze (though usually in this situation it's the
rads that go first).
If you do go away for a while, remember there's always the chance of an
unexpected cold snap so it's best to keep the heating and hot water on, maybe at
a lower temperature, for the whole time. There's no harm in turning off the
mains water supply and closing the valves on the hot and cold down services just
in case. But draining down is not the wisest thing to do unless you cannot
provide any heating at all, and then you should properly drain down ALL pipes
and tanks, including the hot water cylinder.
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