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Cosella-Dörken News

New water retention and drainage membrane for garden roofs.

The new DELTA®-FLORAXX is a highly effective drainage board and water retention system in one product. The newly developed dimple structure provides this product with a high drainage and water retention capacity, as well as a high compressive strength.

A new dimpled membrane specifically designed for use in garden roof applications is being introduced by Cosella-Dorken. DELTA®-FLORAXX is idealy suited for drainage and water retention in extensive green roof systems. The product substitutes a mineral drainage layer (gravel) at a significantly lower weight and less installation height. Through the special octagon-design of the dimples and the additional reinforcement ribs the product has an extremely high compressive strength. The installation is simple and fast - the product is available in rolls and can easily be installed on flat roofs. A geotextile - acting as a filter fabric - is installed over top of DELTA®-FLORAXX to prevent the clogging of the drainage core with fine particles. The product provides a highly effective and economical basis for garden roof applications.

Economical solution: Two functions in one product

With an increasing awareness for environmental concerns the occurrence of green roofs has been growing significantly over the last number of years. Especially in retrofit projects there are often limitations in regards to possible height of a garden roof, or the weight of the materials that can be applied to an existing structure.

In most cases a conventional mineral aggregate layer for drainage is therefore not a feasible option. Not only is it necessary to provide an effective drainage layer in garden roof applications to avoid stagnant moisture that can harm plants. Extensive green roofs typically also require a water retention layer so that the plants can endure extended periods of drought. The new DELTA®-FLORAXX provides both functions in one comprehensive product.

The newly developed dimples with a height of 20 mm provide this double function. The product has a drainage capacity of 10 l / s m. At the same time the dimples can retain up to 7 liters of water per square meter. Surplus water is being drained through a perforation in the dimpled sheet, where it can freely drain to the roof drain. Due to the octagon-shape dimples with additional reinforcement ribs the material provides a compressive strength of 200 kN/m² and is hence suitable even for high substrate loads.

Fast and economic installation

The new dimple sheet can be easily installed by unrolling it with the studded protrusions facing down. The roll size of 2 m x 20 m makes the installation very fast and efficient. Due to its light weight the product can be easily handled by the installer. Due to its high compressive strength the product withstands the rigors of jobsites and the further steps of garden roof applications, i.e. wheelbarrow traffic, etc.

It is recommended to install a suitable geotextile filter-fabric to avoid clogging of the drainage space or the water retention cups. The growing medium is then simply placed on top of the geotextile.

DELTA®-FLORAXX is made from a premium HDPE and is therefore exceptionally durable. The material is resistant to chemicals, resistant to root penetration, and it won't rot when in contact with soil or growing medium.

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DELTA® is a registered trademark of Ewald Dörken AG, Herdecke, Germany.
Incorporate DELTA® Products into your plans quickly and easily by downloading our design files from

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