wet bathroom walls

[fozzie52]

My parents bathroom has a nasty wet patch on some of the bathroom walls. They think it's condensation but it seems excessive to me? It's a lean-to extension, they said they've had a "new roof" on it, but they also had me go along the seam where the roof joins the structure of the house with tube of sealant because apparently the roofers forgot. The rain doesn't seem to affect it though.

They have an extractor fan which is at the other end of the bathroom that comes on/off with the light switch, would having it run longer be beneficial? Or just cheap paint maybe? Thanks.

 

[blup]

Was the new plaster allowed to dry out before painting? It can take a long time especially if it’s on what was previously a damp external wall

 

[fozzie52]

Apparently it started happening shortly after they bought the house. I think the bathroom had been done a while before that though. There's also a patch on the opposite side of the bathroom, part of the newer extension (third pic).

 

[foxhole]

Roofs leaking , how about some exterior photo ‘s.

 

[fozzie52]

Oh no. That does make sense but i was still hoping that wasn't the answer. This is the best I can do today without climbing on the roof but let me know if you want more photos. The first one is where my father asked me to fill the gap, which goes the whole way along, and the others are above the problem area, where there's that corner. Thanks for your reply.