The flat where I live has a flat roof. Each winter the ceiling in one of the rooms suffers severe condensation along one side. The radiator in the room is on the opposite side of the room from where the condensation appears. Would it help to move the radiator from its current site to under the window? If not, what should I do to get rid of the condensation? I tried pasting a thin polystrene foam insulator to the ceiling but it fell off!