Just noticed this brown stain above my living room window. I don’t have a ladder at the moment so can’t reach it to touch it but the wallpaper near it is starting to lift so I think it might be damp. But it’s on the ground floor and there doesn’t appear to be anything else around it or in the room above it. My bathroom is on the floor above too but to the right. Could it be water travelling from the bathroom down or getting in from outside? It hasn’t rained locally since Saturday.
Doesn’t even have to be rust, wallpaper glue turns that colour when it gets wet. My grandma’s farmhouse still has a few small patches like these in some rooms. The old tile roof had tiny leaks in the 60’s, they fixed the roof but never had time to start tearing the room ceilings open while running the farm.
We had the patchy room ceilings checked for microbial damage and moisture ~20 years ago by a pro and they were all clean.