Damp Looking Marks On Walls?

[angie55]

I’m going to decorate one of my rooms. I’ve removed the books and book shelves and found damp looking marks on the walls. They are external walls. I don’t think it’s actually damp. Doesn’t feel damp, just cold. Is it caused by a lack of air getting to the walls because of all the books? Do I need to paint the walls with some kind of primer before I paint them? Thanks for any advice.

[snowshoe1]

SOUND LIKE THERE IS MOISTURE COMING FROM SOME WHERE. I WOULD BLEACH THE WALL DOWN, LET DRY,AND THEM GET A GOOD PAINT THAT HAS A PRIMER IN IT. HOME DEPOT HAS A VERY GOOD PAINT IT CALLED BEHR. THIS IS THE ONLY PAINT I WILL USE.

[theshedman]

It could be caused by lack of air getting to that area. If it doesn't feel damp then maybe it is just that the rest of the wall paint has faded over time and that bit still has the original colour so looks damp. Try washing it off then giving it a coat of paint and see if the dark comes back through. If it does then it could be damp , if not then painting as normal should be fine. If it looks a bit like mould then wash it off with Dettox or similar before painting.

[The Builder]

Condensation on a cold external wall, Angie. Made worse by a lack of air circulation because of the books.
Let it dry out and re-paint.

[angie55]

Thankyou for your answers.