Impermeable roofing underlay offering major benefits over traditional bitumen and reinforced plastic felts. Twin-ply construction of polypropylene non-woven spunbound layer and PP film. Unaffected by temperature change. Absorbent undersurface prevents condensation drip-off. Lightweight, easy to cut and install. Can be used in all pitched roof constructions, whether insulation is at ceiling joist or rafter level or as a temporary cover for up to 3 months. BRE and Wimlas certified.