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ND WSE lt / hd Water Retention Elements

Water storage and retention elements made of polypropylene for surface drainage and water buffering used in the Nophadrain Systems for intensive green and trafficable roofs. The elements can be combined with flow restrictors for the suitable regulation of drainage.

ND WSE lt / hd Water Retention Elements
ProductND WSE lt Water Retention ElementND WSE hd Water Retention Element
MaterialPolypropylene (PP) 100% recycling materialPolypropylene (PP) 100% recycling material
Open volumeapprox. 94%approx. 94%
Open surface63%63%
Durability50 years50 years
Dimensionsapprox. 0.6 m x 0.6 m x 80 cm*approx. 0.6 m x 0.6 m x 80 cm*
Accessories11 connectors per m² (connection at 1 side), 22 connectors per m² (double side connection)11 connectors per m² (connection at 1 side), 22 connectors per m² (double side connection)
Compressive strength (kN/m²)approx. 500 (for height 80 cm)approx. 1,750 (for height 80 cm)
Weight (kg/m²)approx. 2.2approx. 2.5
*available in other heights on requestavailable in other heights on request


Both series are designed for the use under heavy structures on roofs without fall and are therefore suitable for temporary storage or water buffering of excess water caused by possible discharge restrictions into the sewerage system due to e.g. heavy rain.

Elements of both series are available in different heights. The required amount of water buffer can be achieved by choosing the right build-up height; provided that the water buffer is in compliance with the local building regulations. To establish targeted definitions of the discharge volume the appropriate throttle system can be combined with water retention roof build-up.

ND WSE hd series are suitable for SLW60 and due to its high compressive strengths the appropriate system for the use under traffic areas. The elements of the ND WSE lt series are designed for SLW30 and therefore suitable for the use in intensive green roofs and light trafficable (pedestrian) areas. With increased demands on the water supply to the vegetation, products of the ND WSE lt series can also be used for permanent water buffering.

Due to the special design, the water retention elements can also be used on inverted roofs.


The elements of the ND WSE series need to be interlocked with special connectors in order to assure best force transmission. For protection of the waterproofing membrane or the thermal insulation, both series need to be combined with appropriate protection layers e.g. ND TSF-100 Slip and Protection Sheet and ND FV-300 Filter Geotextile as filter layer.