damp loft joist

[jeffreyw]

basically have been stripping the wall paper of my upstairs toilet and the plaster came off with it
i could see the brick work at the top was damp and so was the wood above in the loft
it is directly above an air vent(the wood)
i went up in to loft and inspected the felt which was slightly damp
i had my roof checked out a few month ago all the tiles look ok the guttering looks sealed and sound any ideas as to what to do?

 

[^woody^]

If the felt in the loft is damp, then its most likely condensation, but you will see where it is running down and dripping near to the ceiling.

If there are no obvious signs in the loft, then get the roof looked at again - especially at the eaves.

Damp at the wall would be very extreme for condensation as the cause. But if there is moisture getting in at the eaves, then rot can set in very quickly at this location