DIY Doctor UK DIY Forums

Hi. We had a loft conversion about 2 years ago, there's damp running horizontal along the wall, any thoughts or ideas on where water could be creeping in? We have a pitched roof (Slate), the damp is on the 1m external wall (see drawing). Advice would be appreciated, I understand it could be very difficult to narrow this down! Thank you.

Hi kingshaves,
Most likely cause is condensation within the roof/wall structure. Without knowing how the walls/roof were insulated and what was done to deal with damp penetration it is, as you say, difficult to narrow it down.
Regards S