Hello, we had water penetrating through our bedroom walls for the last 4 years. As it is where the roof and chimney meet, we’ve been told it was an issue with the lead work which was changed twice. The second time was 5 weeks ago, we waited for 4 weeks for the wall to dry and had the room replastered a week ago (after the old mouldy plaster was taken off). Unfortunately, the plaster near the chimney only dried in a few places, and now the stains we were struggling with are reappearing again. We have no idea why this is still an issue and how to fix it. The strangest thing is that the stains only appear during the night. We wake up in the morning to a wet wall, leaving the windows open and using a dehumidifier help dry the majority of the stains but not all of it completely and anyway it reappears the following morning. Any suggestions on what the issue could be? Many thanks for your help.
Photo 1 is what the wall looks like in the morning
Photo 2: the same wall after a full day of window opened and dehumidifier on
Photo 3&4 are whilst the platerer was taking off the old plaster
Photo 5 was the problematic wall before the lead work and new plaster