The water storage tanks are mainly used on green flat roofs. They store excess rainwater which can be used for the planting to bridge subsequent dry periods. This system is particularly recommended for a flat roof with intensive green roofs, because grasses, shrubs and even small trees are used. And they need a greater quantity of water and require more maintenance. On the other hand, waterlogging must not form on the green roof since it may attack the roof structure and result in a root rot inside the vegetation layer.
The high-performance DELTA® water storage tanks fulfil a double function with one product because they store and drain at the same time, depending on the water quantity. This means that they can also briefly relieve the sewage system in case of a heavy rainfall. Thanks to their innovative technologies and outstanding product features such as for example, their high-pressure resistance, the DELTA® water storage tanks are the ideal solution for green roofs.
The water-storing drainage sheets DELTA®-FLORAXX and DELTA®-FLORAXX TOP are perforated dimpled sheets laid between the flat roof waterproofing and the vegetation layer of the green roof. In case of a rainfall, the sheets store the rainwater in the knobs. This permits an absorption of up to seven litres per square meter. Excess water runs through the perforations under the dimpled sheet. From there, it is drained to the roof drainage through the roof waterproofing.