In order to dry line a wall, start by removing all wall coverings and skirting boards. Remove any present mould using a fungicide and then secure battening around the perimeter. Using a 400 mm interval, place, vertical battens across the wall's centre and align it using a straight edge. Next, fit the polystyrene and staple the membrane over the battening. Finally, fix the plasterboard, tape and joint the wall area.