It is intended for making water-vapour-tight insulation in structure of roofs, walls, and ceilings. It provides indispensable roof protection against moisture. It stops water vapour pressing onto thermal insulations from within the rooms. It is characterized by high water-vapour-tightness, strength and resistance to cracks. Together with mineral wool and a water vapour permeable membrane, it forms a tight roof system. In addition, the water-vapour-tight film can provide a perfect layer resistant to moisture used under floors, flooring, jointless floors, etc.