High-performance, CE-marked drainage system with a perforated core for extensive green roof on an inverted roof. Also applicable in the Nophadrain Water Retention Systems (intensive green roof / trafficable roof) with inverted roof constructions. The drainage system prevents the build-up of hydrostatic pressure on the waterproofing membrane. The vapour-permeable geotextile on the back protects the XPS insulation from mechanical loads and ensures that vapour is able to evaporate freely from the XPS insulation. It's a 3-in-1 product (on roll) consisting of a filter geotextile and a vapour-permeable geotextile that are glued (not thermally bonded) to the dimpled core.