Water retention systems | extensive green roofs

The water retaining and retarding system suitable for extensive green roofs that contributes to sustainable and climate-proof cities.

The core of this water retention system for green roofs is the ND WSE-100lte Water Retention Element. These elements slow down water drainage during heavy rain showers and have a temporary water storage of 95 l/m².

Nophadrain recommends combining water retention with water buffering. By adding the ND SM-25 or ND SM-50 Substrate Panels to the extensive substrate, an additional 15 or 30 l/m² of water can be buffered on the roof.

Technical data

Cuttings
Plug plants
Blankets
Recommended substrate height
approx. 80 mm
approx. 80 mm
approx. 50 mm
Total system height
approx. 180 mm
approx. 180 mm
approx. 180 mm
Total system weight, dry
approx. 43 kg/m²
approx. 43 kg/m²
approx. 25 kg/m²
Total system weight, saturated
approx. 177 kg/m²
approx. 177 kg/m²
approx. 155 kg/m²
Water buffering
approx. 134 l/m²
approx. 134 l/m²
approx. 134 l/m²
Run-off coefficients
set discharge value
set discharge value
set discharge value
Temporary water retention
approx. 95 l/m²
approx. 95 l/m²
approx. 95 l/m²
Type of vegetation
extensive vegetation
extensive vegetation
extensive vegetation
Slope in degrees

Example composition

Extensive vegetation (blankets, plug plants or cuttings)

Root-resistant waterproofing membrane

from approx. 180 mm
from approx. 43 kg/m²
from approx. 155 kg/m²
approx. 134 l/m²
Cs = 0.09 l/s - 3.08 l/s

One complete system

Our water retention systems for extensive green roofs are supplied complete, from filter geotextile, water retention element, protective geotextile to the growing-medium layer and vegetation. We grow the vegetation ourselves in our sedum nursery and it is of excellent quality. If the waterproofing membrane is not root-resistant, we recommend adding the ND WSB-50 Root Barrier.

In combination with the ND AFC-100 Adjustable Flow Control (adjustable to reduce water flow to 0.04 l/s), this system provides the best basis for any water retention system for extensive green roofs. The water discharge is adjusted to the calculated discharge values by turning the adjustable pressure regulator to the desired position and setting it equal to the discharge coefficient table.

Advantages of the combination of water retention and water buffering
The ND SM Substrate Panels are installed on top of the water retention elements and buffer water up to the saturation point. The water is made available for vegetation and this promotes important evaporation. This way, only the excess water flows through to the water retention layer. The substrate height is determined by the type of vegetation: sedum blankets, plug plants or cuttings.

By adding an extra, long-term water buffer, the vegetation has a water supply during dry periods. More and healthier vegetation means more evaporation and transpiration, which helps to lower temperatures in urban areas. This contributes to a healthier and more livable city climate.

Weight reduction
The ND SM-25/ND SM-50 Substrate Panels can reduce the weight of the composition, as they can (partially) replace the substrate.

Generic filters
Exact matches only
Filter by Product categorieën
Green roof packages
Root barrier layer
Water buffering and water retention layer
Trafficable roofs
Vertical protection and drainage layer
Vegetation layer
Solar roofs
Growing medium layer
Roof edge / edge retaining profiles
Filter and drainage layer
Separation, protection and slip layer
Filter layer
Green roofs
Sedum cassettes
Erosion protection
Water retention
Inspection chambers
Generic filters
Exact matches only
Filter by Product categorieën
Green roof packages
Root barrier layer
Water buffering and water retention layer
Trafficable roofs
Vertical protection and drainage layer
Vegetation layer
Solar roofs
Growing medium layer
Roof edge / edge retaining profiles
Filter and drainage layer
Separation, protection and slip layer
Filter layer
Green roofs
Sedum cassettes
Erosion protection
Water retention
Inspection chambers
Generic filters
Exact matches only
Filter by Product categorieën
Green roof packages
Root barrier layer
Water buffering and water retention layer
Trafficable roofs
Vertical protection and drainage layer
Vegetation layer
Solar roofs
Growing medium layer
Roof edge / edge retaining profiles
Filter and drainage layer
Separation, protection and slip layer
Filter layer
Green roofs
Sedum cassettes
Erosion protection
Water retention
Inspection chambers
Generic filters
Exact matches only
Filter by Product categorieën
Green roof packages
Root barrier layer
Water buffering and water retention layer
Trafficable roofs
Vertical protection and drainage layer
Vegetation layer
Solar roofs
Growing medium layer
Roof edge / edge retaining profiles
Filter and drainage layer
Separation, protection and slip layer
Filter layer
Green roofs
Sedum cassettes
Erosion protection
Water retention
Inspection chambers