Penetrating Damp

[Dphily]

Hi. Damp course installed and old plaster chipped off to 1.4m and entire wall skimmed. However, this spot won’t dry out, it fades then comes back. I’ve photographed the inside of the wall and the corresponding wall outside. To me it looks pretty sound and the pointing looks good. Could it just be pourous bricks? Advice please. The white tape on the window is the height of the damp line.

 

[Dphily]

More photos

 

[DIYRules]

It looks like penetrating damp, given the pointing on the exterior wall looks so old this is very possible. There is probably a crack or hole in it that is letting the damp through. You could try treating the exterior wall with waterproof masonry paint. However, that section should probably be repointed.

 

[Silentrunning]

I would also have a look at the roof. Many times a small roof leak can seep down a wall and exhibit problems like the one shown in your pictures. It looks like the ceiling is also damaged which would be unlikely if it was just the exterior wall leaking.