Chimney Damp (flues)

Hi all, first time post but id imagine ill be here quite a lot soon .

just brought my first house and there is damp in the back bedroom. The valuation showed the damp up as something to do with the chimney flues. Now the chimney isnt in use (there is two chimneys one at the font and one at the back).
The back chimney is the one with damp and there is nothing connected to it (fires have been removed. Id have to double check with next door but itonly connects to their kitchen.
Firstly, what would be the best way and roughly how much would it cost, can it be done manually?

Secondly because it isnt in use can we block it up (fit some air bricks) or would this not solve the problem. Thanks

the redundant chimney vents should be capped off with a vent terminal to prevent water ingress, there should also be a vent fitted if the fireplace is removed and sealed over.
this is to create an airflow in the vent which should prevent dampness.

Hi. The advise given is most important, circulation of air helps to keep the stack dry. But i would also give the stack a coat of clear sealant this will help to stop water being absorbed in to the masonry a down into the property. On new build chimneys sheet lead dpc or chimney trays are used to stop this problem. Good Luck