On 18/12/2020 10:36, Monique Castellani-Kraan wrote:
No leaky roof as far as I know, we did recently have the roofers round for maintenance. Had a leaky bay window that needed the lead flashing repairing. I am wondering if Alan is right and condensation is the cause - we have had an awful problem with it in the house in recent years and ended up needing a dehumidifier.

You only get a 'roofer' in if you know you have a problem. Out of 20
jobbing 'roofers' yo will be lucky to get just 1 that is any good.

Bay windows with flat roofs are notorious for leaks and condensation.

If you need a dehumidifier full time then that suggests a more serious
problem.

What sort of heating do you have ?.
Do you use showers or take baths ?.
Do you do a lot of cooking ?
Do you use a tumble drier indoors without a vent kit ?.
Does the property have cavity walls that are uninsulated ?.
How much insulation is in the loft ?
Are you in an exposed area as defined by building regs ? (i.e.
somewhere on the west and south coasts with more driving rain).
Does the property have cavity walls or solid walls ?.