Vegetation base layer: Nutrient medium and root space for greening. It can be introduced, for example, as a bulk material, or in mat/board form and is usually composed of organic (e.g. special humus soils, treated topsoils) and mineral (e.g. lava, pumice, expanded clay, broken bricks) components in a fixed weight ratio. In the case of vegetation mats, both mats with rot-proof and permanent carrier inserts are available.
Filter layer: between the vegetation base layer and the underlying drainage layer, prevents the slurry of fines from the vegetation base layer into the drainage layer. Geotextiles in non-woven or woven form are used for the filter layer, which must be rootable, as the underlying drainage layer serves as an additional root space, especially at low installation heights.
Water storage/drainage layer: The main task of the drainage layer is to drain the surface water seeping through from above to the roof drains. In addition, depending on the formation and layer structure, the drainage layer can also serve as a water storage layer or to enlarge the root area. The drainage layer can consist of profiled or studded panels made of plastic or rubber, but also of bulk materials such as gravel, chippings, lava or expanded clay or special foam or textured fleece mats.
Protective layer: the protective layer protects the underlying seal (and possibly also the separate root penetration protection) from mechanical damage. For example, plastic sheets, geotextiles or drainage mats/plates can be used as materials.
Root penetration protection: in any type of green roof, the underlying waterproofing must be protected against damage caused by penetrating roots. This can be done either by the top layer of the waterproofing itself, if this is appropriately permitted, or by a separate flat root penetration layer above the waterproofing. If the waterproofing function of the roof is taken over by a ceiling made of waterproof concrete or a welded metal trough, root penetration protection can be limited to any existing movement joints. Some plants, on the other hand, require measures that go beyond root penetration protection in individual cases. Details on root penetration protection are described in the Green Roof Directive under point 6.2. Further information on the subject of waterproofing and root penetration protection can be found at ►222│Waterproofing flat roofs made of bitumen/polymer bitumen membranes and at ►223│Waterproofing flat roofs made of plastic/elastomer membranes.
Source: bauwion
