Drainage

Our DBGS DRAIN 8 is a three-dimensional mono-filament structure which consists of two filter fleeces with a mat of polymeric entanglements with large cavities in between. The layers are thermally bonded to one another.

Because of its specific construction, DBGS DRAIN 8 fulfils three roles:

  • it drains any excess water;
  • it protects the underlying waterproofing membrane from mechanical damage;
  • it filters the small substrate particles, avoiding any clogging of the drains.

Water-retaining layer

In order to achieve sufficient water retention, we sometimes put water-retaining geotextile or mineral wool on top of the drain mat. Whether this is needed or not, depends on the chosen vegetation, on the maximum installation height and on the roof load.

Growing medium

This is the layer in which the vegetation roots. As such, it is the vital component of the green roof system. It consists of either a mineral substrate or a water-retaining layer.
As the plants’ nurturing ground, the substrate most not only have the right physical, chemical and biological composition, it must also have proper ventilation and water management.
We determine the thickness of this layer based on the intended vegetation. The larger the plants, the thicker the substrate layer will need to be.

Vegetation layer

In the case of intensive greening, there are hardly any limits: flower beds, a lawn, shrubs and even trees. Extensive greening is limited to sedum, moss and sometimes herbs.

Attention: plants which root aggressively or plants with tap-roots are not suited for green roofs.