On 01/01/2021 11:18, wrote:
Hi all and Happy New Year,

I'm trying to find the best solution to a condensation problem in a loft in a 1980's new built block of flats (top floor flat with loft access).

The condensation forms on the inside of the roofing felt then drips down onto stuff stored up there. The loft is well insulated just above the ceiling. I don't want to increase ventilation due to water pipes being up there (as I don't want frost damage).

Maybe some sort of screen fitted over the rafters or some kind of insulation between the rafters? What would people suggest as a cheap and easy to fit solution? It does not have to look good.

Thanks

S

Do the top floor flat(s) have downlighters ?. These,
especially if fitted in bathrooms where an electric
shower is in use will allow moisture vapour into the
loft. Properties built in the 1980's may not have
had enough (or any) loft ventilation and if the top
floor flat owners have added more insulation in there
they have made the loft colder so increasing the
chance of condensation.

Where in the country is this building ?. Does it
stay in shadow a lot at this time of year (so the
solar gain does not warm up the loft) ?.

Have any other flat owners done something silly like
fit a new kitchen and terminate the cooker hood inside
the cavity wall ?.

You imply that the water tanks are in the loft. Do they have
tightly fitting lids ?. If not, get them retrofitted.
A slab of 4 inch celotex is better than nothing. If they are
well insulated make sure there no insulation under the tanks
and 'building regs' pipe insulation (with 19mm walls) should
protect the pipes. Pay attention to bends.

Apart from that, just make sure any stuff you store up there
is inside sealed plastic bags for protection.