Our double garage was converted before we moved in many years ago, the converted half is now used as an office and occasional crashing room (sofa bed). The room is damn cold though and there appears no real insulation between the wall and the garage.
Its a block and brick wall so would I be best off using insulated plasterboard inside the garage? If so, do I screw the board straight into the bricks/blocks or batten first then screw into the battens? If the latter, should I also squeeze some rockwool type stuff into the gap or could that lead to damp?