Difference between a vapor barrier and a waterproof breathable membrane
The technology of waterproof breathable membrane has been introduced from European and American countries. However, the production technology of domestic products is varied, and the quality of each manufacturer is uneven, and it can not form a unified quality standard. In fact, waterproof breathable membrane mainly consists of three layers: PP spunbonded nonwoven fabric, PE polymer breathable membrane, PP spunbonded nonwoven fabric. The main functions of spunbonded nonwoven fabrics are to strengthen tensile force and hydrostatic pressure and to protect the middle layer (air permeable film), and the real air permeability mainly depends on the middle layer of PE polymer air permeable film.
Vapor barrier and waterproof breathable membrane are generally used for metal roofing.
1. Vapor barrier for waterproof effect is very good, but the building structure of water and gas can not volatilize, this metal roof will certainly rust.
2. Waterproof breathable membrane can be said to be an upgraded version of the air-proof membrane, which can effectively waterproof, and release water vapor to prevent metal rust.