Venting a chimney breast

[toplondonchef]

Couple of years ago I had the chimney breast removed from the lounge, bricked up and the stack removed from the roof. The portion of the stack built onto the outside wall was left in place and capped just under the guttering with a slate roof tile. No vent was installed. In the past 2 years there has been no sign of damp in the wall but have just recently lined the walls with paper and painted them.

The wall area where the chimney breast was took twice as long for the paper to dry out and after painting, the paper bubbled badly in this area and again took ages to dry out.
Most bubbles in the paper shrank back once dry and a few I had to pierce, paste and then smooth down.
Had no problems with other walls and now dry, the chimney breast area is fine too, no sign of damp, even with all the rain we've had.

Was wondering though should the stack on the outside wall be vented and if so, what's the best method to do this and what type of vent would be recomended.
Wall are 9 inch solid with render finish to outside

Many thanks for reading this and any help

[welsh brickie]

yes install a 9x3 clay airbrick externally in the stack near the top.

[toplondonchef]

Thanks for your reply welsh brickie
Now all decorated and no further signs of any damp but will go ahead and fit airbrick as you suggest
Thanks once again