A vapour control layer (VCL) is a thin sheet—usually polythene or foil‑backed membrane—installed on the warm side of a building’s insulation to slow down the movement of water vapour from inside the building into the structure, preventing condensation from forming within walls, roofs, or floors. It doesn’t stop moisture completely, but it provides enough resistance to keep insulation dry, protect timber and metal components, and maintain the building’s thermal performance.
Tyvek® AirGuard® Smart regulates the humidity in building elements.
