We have an old fireplace which has been plasterboarded and plastered over. In front of this we have a wood burning stove, with a pipe which goes up to the original chimney in the roof. (outside the wall up until the chimney in the attic).
The plaster behind the stove is cracking.
From tapping on the wall it sounds hollow behind, so I think they have literally put plasterboard over the hole but not bricked up the old fireplace. I think the air is getting heated and expanding, pushing the plaster out as there is no longer a link to the chimney from the air gap.
I want to cut out the plasterboard where it is cracking (the crack forms an actual outline of the board - approx a meter by half a meter), brick up the hole and then plasterboard over the brick to match the room.
From reading around, when you brick up a fireplace you should put in an air block. Is this needed if there is no route to the chimney anymore?
If it is, can the plasterboard go over the air brick, or does it have to be left open to the room?
Would I have to brick the hole, or could I fill it with, eg expanding foam or similar?
What is the best way to remove the plasterboard so I can reuse it? (it is heatproof plasterboard so expensive)
