I'm planning to dry line the walls of a room with 2" battens, 2"
polystyrene between them and 1/2" plasterboard on top. The
plasterboard will then be painted (no plaster or wallpaper). I also
want to install a woodburner in the room (obviously I will have to
allow for a hole in the wall for the flue to go into the chimney,
which will be lined with a flexible flue liner).

What I need to know is: how far should the woodburner be from the
walls in order to stop it damaging them. Although I know that
plasterboard is fire retardant, I assume you can't have a heat source
too close to them permanently. Is the 6" of hearth enough, or do I
need more?