Trade Select™ VapourTech® Wall is classified as Air Barrier, Water Barrier and Class 4 Vapour Permeable. Very high levels of water vapour are allowed to absorb and diffuse through the core non-woven structure, ensuring that condensation risk is controlled, while outside liquid water cannot penetrate inwards. Trade Select™ VapourTech® Wall is chemically non-reactive in conjunction with treated timber and salt conditions close to coastlines.