Water retention systems | intensive green roofs

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

The core of this water retention system for green roofs is the ND WSE lt Water Retention Element. These elements slow down water drainage during heavy rain showers and have a temporary water storage between 47 and 142 l/m² (depending on the height of the chosen height of the element: 50, 80, 100 and 150 mm). We recommend the ND WSE-100lt with a height of 100 mm and compressive strength of > 400 kN/m² for intensive green roofs.

Nophadrain recommends combining water retention with water buffering. By adding the ND WSM-50 Water Reservoir Panels to the intensive substrate, an additional 40 l/m² of water can be buffered on the roof. The panels are installed on top of the water retention elements and buffer water up to the saturation point. This way, only the excess water flows through to the water retention layer. The substrate height is to be determined by the type of vegetation, the desired water buffering and the maximum load on the roof.

Technical data

Low
Middle
High
Recommended substrate height
approx. 250 mm
approx. 500 mm
approx. 1,000 mm
Total system height
approx. 354 mm
approx. 604 mm
approx. 1,104 mm
Total system weight, dry
approx. 258 kg/m²
approx. 508 kg/m²
approx. 1,008 kg/m²
Total system weight, saturated
approx. 429 kg/m²
approx. 754 kg/m²
approx. 1,404 kg/m²
Water buffering
approx. 170 l/m²
approx. 245 l/m²
approx. 395 l/m²
Temporary water retention
approx. 95 l/m²
approx. 95 l/m²
approx. 95 l/m²
Run-off coefficients
set to discharge value
set to discharge value
set to discharge value
Type of vegetation
Intensive vegetation
Intensive vegetation
Intensive vegetation
Slope in degrees

Example composition

from approx. 354 mm
from approx. 258 kg/m²
from approx. 429 kg/m²
from approx. 170 l/m²
Cs = approx. 0,09 l/s - 3,08 l/s

One complete system

Our water retention systems for intensive green roofs are supplied complete, from filter and protective geotextile, water retention element to the growing-medium layer. If the waterproofing membrane is not root-resistant, we recommend adding the ND WSB-80 Root Barrier.

In combination with the ND AFC-100 Adjustable Flow Control (adjustable to reduce the water flow to 0.04 l/s), this system forms the best basis for any water retention system for intensive 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.

Combine water retention and water buffering
By adding an extra water buffer, the water management on the roof is not only lifted to a higher level – the ND WSM-50 Water Reservoir Panels also function as an extra ‘filter layer’. This allows substrates with a higher organic content to be used. This allows biodiverse vegetation on the roof, increasing transpiration and evaporation of precipitation and lowering ambient temperatures. Completely in line with our motto: “Catch it, Keep it, Re-use it”.

Weight reduction
The WSM-50 Water Reservoir Panels can reduce the weight of the structure, as they can (partially) replace the substrate.

Generic filters
Exact matches only
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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