Waterproof and breathable membrane is mainly applied to steel structure and wood structure buildings in the field of construction. The domestic market is quite chaotic. Most brands promoted through the network do not have the ability to produce waterproof and breathable membrane, but adopt fake and shoddy products simply compounded with non-woven fabric and glue. Formal brand recommendations refer to the national standard design atlas 06J925-2 "profiled-steel plate, sandwich panel roofing and wall building structure (two)".

Working principle of waterproof breathable film:

In the state of water vapor, water particles are very small, according to the principle of capillary movement, can smoothly infiltrate into the other side of the capillary, so as to occur steam permeability phenomenon. When the water vapor condenses into water droplets, the particles become larger. Due to the effect of the surface tension of water droplets (water molecules "pull against each other "), the water molecules can not smoothly break away from the water droplets to penetrate to the other side, which is to prevent the occurrence of water infiltration, so that the vapor permeable film has the waterproof function.

Waterproof and breathable film material:

Waterproof and breathable film technology was first introduced from European and American countries. However, the production process of domestic products is varied, and the product quality of various manufacturers is uneven, which fails to form a unified quality standard. In fact, waterproof breathable film is mainly composed of three layers: PP spunbond non-woven fabric, PE polymer breathable film, PP spunbond non-woven fabric. The main function of spunbond non-woven fabric is to enhance the tension and hydrostatic pressure and protect the middle layer (permeability film), the real permeability is mainly by the middle layer PE polymer permeability film.