Is a Vapour Control Layer (VCL) required in a floor?
If the insulation is to come into contact with a concrete slab or screed a membrane needs to be laid on the top side of the insulation that the slab or screed is to be laid. This is to protect the foil in the surface of the board from the concrete/screed, it also provides a barrier to stop water contained in the finish from penetrating through the board joints, it also stops the board joints being opened by the concrete/screed and causing a thermal break. If a floating timber floor is to be laid then the VCL should be laid directly below the floor finish.
