Edward Thompson
Hi Eleanor it sounds like the dormer has no insulation , you would need to remove the plaster board on the side walls and ceiling to fit a foil backed rigid insulation board such as "kingspan or celotex" . Re-board with foil back plasterboard or insulated plasterboard if you have the room to fit them and then skim. To check if your walls are insulated cut a small hole in the plasterboard to verify if there is any insulation. It maybe possible to just overboard the walls with insulated plasterboard but it would not be the best solution. Thanks. Ed
