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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. Due to the special design, the water retention elements can also be used on inverted roofs. The elements can be combined with flow restrictors (e.g. ND AFC-200) 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. 95%approx. 95%
Open surface63%63%
Durability50 years50 years
Dimensionsapprox. 0.6 m x 0.6 m x 100 mm* (standard height)approx. 0.6 m x 0.6 m x 80 mm* (standard height)
Compressive strength (kN/m²)approx. 400 (for standard height 100 mm)approx. 1,050 (for standard height 80 mm)
Weight (kg/m²)approx. 2.9 (for standard height 100 mm)approx. 2.5 (for standard height 80 mm)
*Available in other heights on request50, 80 and 150 mm50, 80 and 150 mm


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.

The 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 an adjustable flow control system (e.g. ND AFC-200) can be combined with a water retention build-up.

The ND WSE hd Water Retention Elements 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.

For protection of the waterproofing membrane, ND TSF-100 Slip and Protection Sheet has to be placed underneath the ND WSE lt / hd Water Retention Element. In case of an inverted roof the ND TSF-100 has to be exchanged by the ND 100sv Drainage System. As filter layer, the ND FV-300 Filter Geotextile has be used.


The products from the ND WSE series need to be interlocked with special connectors in order to assure best force transmission. For the ND WSE elements with heights of 50 and 80 mm use the Connector Small; for heights 100 and 150 mm use Connector Large. Recommended quantity: for ND WSE-lt: 6 connectors per m2; for ND WSE-hd: 12 connectors per m2 (available per bag (50 pieces)).

Other heights available on request:

Product Dimensions Compressive strength (kN/m²) Weight (kg/m²)
ND WSE-50lt approx. 0.6 m x 0.6 m x 50 mm approx. 500 approx. 1.5
ND WSE-80lt approx. 0.6 m x 0.6 m x 80 mm approx. 500 approx. 2.0
ND WSE-100lt approx. 0.6 m x 0.6 m x 100 mm approx. 400 approx. 2.4
ND WSE-150lt approx. 0.6 m x 0.6 m x 150 mm approx. 400 approx. 3.4


Product Dimensions Compressive strength (kN/m²) Weight (kg/m²)
ND WSE-50hd approx. 0.6 m x 0.6 m x 50 mm approx. 1,050 approx. 1.6
ND WSE-80hd approx. 0.6 m x 0.6 m x 80 mm approx. 1,050 approx. 2.1
ND WSE-100hd approx. 0.6 m x 0.6 m x 100 mm approx. 700 approx. 2.5
ND WSE-150hd approx. 0.6 m x 0.6 m x 150 mm approx. 500 approx. 3.5