If the roof substrate is in good condition and is suitable for mechanical fixing (i.e. steel, concrete, timber, plywood or Sterling Board) Dryseal can be fixed over the existing coverings and insulation. Pull out tests may be required to ascertain the frequency and security of fixings. NOTE – ‘Stramit’ compressed straw board decking and chipboard are NOT suitable to be mechanically fixed over. They are unlikely to remain serviceable for the life of the Dryseal system.