PAROC XMV 020 air/vapour barrier is a polyethylene film for use as an air and vapour barrier mainly in flat roofs. The air/vapour barrier is an age-resistant transparent LD polyethylene film which creates an air/vapour tight layer on the inner side of an insulation layer. A continuous barrier prevents building damage by preventing air and moisture movement through the porous insulation layer. The seams have to be overlapped and taped. Size and double folding are different for PAROC XMV 12zcf and PAROC XMV 012.