Is a vapour control layer (VCL) required in a floor?

Category: RenovationInstallation

In addition to the damp proof membrane (normally a 1200-gauge polythene sheet below the insulation), a 500-gauge polythene VCL should be laid over the insulation. Where a concrete slab or a screed is to be poured on top, the VCL will also protect the foil face of the board from alkalis within the concrete, and stop poured concrete opening board joints and causing a thermal break.