Vapour membrane has good waterproof performance, can effectively block the invasion of wind and rain on the room, can effectively prevent the invasion of cold air, has the effect of protecting the insulation layer and energy saving. Used together with other insulation materials (glass wool, rock wool), it can effectively prevent water vapor from invading the insulation layer, form a comprehensive protection of the insulation layer, ensure the effect of the insulation layer, so as to achieve sustainable energy saving and improve the durability of the building.