Strictly speaking, I'm not wanting to insulate my bathroom, but the builder refurbishing it is proposing plasterboard on battens if the condition of the wall, once exposed, is bad. Obviously this will give some small degree of insulation and therefore some small degree of condensation potential.
The wall in question is solid brick, c. 1895, and on an upper floor, no rising damp. But obviously high humidity within the room.
Is this risky? If so, what precautions can I ask to be taken? Would the floor void have to be dealt with?