We are converting our barn to habitable use and at Building Regs Stage. It is single storey 59m2, the ceiling will slope up to the apex. The walls will be insulated plasterboard with 3mm skim applied, the sloping part will be Birch Plywood, left as its natural colour. Please can you tell me which of your paint systems we should specify for the sloping birch ply surface, which will retain the natural colour of the Birch. Many thanks