Leaking or condensation?

[Newby2]

Hi
There are some brownish marks on the ceiling at two corners (at opposite sides) of my 1st floor master bedroom. Photo of one of the corners is attached. They have been there for a long time. Is it due to condensation? It doesn’t look like leak to me cos after heavy rain it doesn’t change (I checked many times). I got into the loft but due to the awkward location it’s difficult to see. From outside I can’t see any problem with the roof tiles either. Any advice would be very much appreciated.

 

[KenGMac]

Newby2, good evening.

Looks a lot like Condensation to me. you appear to have covered all the basis in investigation, the Acid test is that the degree of discoloration does not fluctuate with rain fall, if there was a roof leak, the ceiling plasterboard would be really black and in a really short period of time the Plasterbosrd will simply collapse.

Possible other considerations? are.
1/. Is this a north or West facing room?
2/. How thick is the loft Insulation?
3/. Possibly off the wall but? how close is the nearest loft ventilation? is it a soffit strip type or is it roof slope mounted?
4/. Do you have and use trickle vents in the windows? [Problem is in your location ventilation = very cold room??]

Ken.