Unexplained damp in bay (split off from old thread)

[cdoddsie]

Hello folks - I’m new to this site. After much Internet trawling this post from the OP was the closest fit to a real mystery we have here. It sounds exactly like our situation, except we are a 1930s semi. The main issue is a damp carpet in ground floor bay window, but absolutely no other signs of water ingress. Radiator new and installed professionally, no evidence of a leak; no evidence of damp on any walls, skirtings or ceilings; no damp timber below the underlay, including floorboards, joists; nothing. Everything is dry, except the carpet in the corner of the bay window. It starts with the first heavy rains and damp period of the year, around Sep/Oct, improves in summer. It has been ongoing for a few years now. Any thoughts, please? OP - did you get any further with finding a solution?

 

[Harry Bloomfield]

I am now at the point of laying toilet paper on every level of flooring and along the window sills (maybe it's dripping off the sills onto the floor directly) to try and isolate the sources of the water, but have yet to have the problem re-occur to be able to pin it down.

Are there any animals in the house?

Could it be condensation on window glass, dripping down? Not all carpet material, with appear wet - sometimes it can go straight through, wetting just the sub-surface. Did your toilet tissue reveal anything?

 

[JohnD]

Please post photos of the outside wall, all the way up to the roof and down to the ground. Include the roof, gutters, downpipe and drain. Please mark in your photos the position of the original slate dampcourse.