Hi, i have a room on the back of the house that we want to use temporarily for a bedroom, 1 of the walls is single brickwork, i would like to know how to go about plastering it correctly to stop damp and insulate it, i have been told i need to battern the walls with a damp proofer, but when i went to b and q, they looked at me gone out !! the roof was polycarb, now its a pitched tiled roof with plaster booard on and insulated lagging in, cheers..