Celing strut marks showing through bedroom ceiling.

pineapple

Hi all
I had a damp problem last year and ended up having my roof and guttering done to sort it. Lately I have been decorating the bedroom and consequently have been staring at the ceiling a lot while trying to decide the colour! Which is when I noticed a faint stripey effect nearest the window. Could I still have damp getting in? Or maybe there is still some damp up in the roof space?
I was tempted to treat it with sealant before painting but I don't want to seal in any moisture. What do you think it is? Methinks cue expensive builder. Sigh...
PS the ceiling feels dry to the touch but I haven't yet dared venture up into the roof space.

iamcornholio

This is what is termed 'pattern staining' and is due to different surface temperatures where the timber joists are.

Insulation between and over the joists will prevent this