neither wall are external. The plaster is not wet or damp. The paint lifts and goes chalky. Below the stairs is another staircase that goes to a cellar.
Given the location of the issues you are having? there is a possibility that the walls were at one time painted with an old form of paint called Distemper.
Distemper at times does not take well to over-coating with modern paint
Yeh it looks exactly like damp . I’ve had a humidity meter in the Hall for the past 6 months and it’s showing dry.
It’s gypsum plastered. Ive read about that efflorescence before or something to do with salts coming through. There is a cellar the floor below, the walls aren’t external, it doesn’t happen on externals walls plastered and painted the same.
When I say it doesn’t feee damp, as in if you flake the paint off the plaster is dry.
Hi Ken, Thanks for the tip. Id seen some videos online of the Efflorescence giving false readings through the two prong damp meters due to salts being conductive so had not bothered. Ill look at the other type but ill certainly try some clingfilm over. Ill use tape to hold it on, not too fussed about marking the walls given there current state.
If it is damp. Do you have any suggestions of were to look? ill try draw I diagram or the area effected to show why I cant understand where its coming from.
The paint issue happens on both walls either side of the stairs. (see drawing and pictures) so the wall to the left of the staircase as looking up the staircase is a internal partition wall between the ground floor room and staircase. If it was only on the party wall then perhaps I could understand a water ingress issue.
The property used to be one big farm house so the roof is one with no parapet. Looking outside on the boundary of the houses the gutters are not joined but separated which could contribute to some water from the roof runing down the wall but they are pretty much touching. I did go outside while it was raining and watch. My neighbours gutter needs cleaning was water was splashing down over his window but its a good 4 meters from the party wall.
I scraped some paint off the wall and stuck a bit of cling over the wall last night, no condensation this morning... ill leave it a few days. Was hard to get it stuck down as the tape just lifted the paint off. I noticed on the sections where the paint had 'bubbled' that the plaster behind it was 'pitted' like the surface of the plaster had crumbled off pushing the paint out. the bubbles are very small and low down. no bigger than 2mm across.
I also ran my hand down the wall to feel the paint, which above feels dry, as I get to the effected part there is a change which feels damp or not warm, like a temperature change. but also that there is more moisture in that area. Its hard to describe because it doesn't feel wet.
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