EXTENSIVE GREEN ROOF
A TOUCH OF BIODIVERSITY
Extensive Green Roof
An Extensive Green Roof represents a natural form of vegetation that is largely self-sustaining and evolving. Certainly, it is the most cost effective and most natural infrastructure to reduce stormwater run-off from buildings at the source. Although, extensive Green Roofs only partially restore the environmental footprint of a structure, it is proven to be the most efficient and most natural.
For instance, the city of Stuttgart in Germany has over 100 Million square feet of extensive Green Roofs in a 30 mile radius from the city center. Hence, this is also the place where this idea literally grew from seed and was perfected in the 1980's. More over, this is the time and place where Jörg Breuning was a part of this movement.
Meanwhile, extensive Green Roofs are the epitome of the term "Green Roof". But still there are many misconceptions, myths and misleading information about extensive Green Roofs. With our website we try to shine light into this information jungle, because we were there from the beginning.
Success in simplicity
An extensive Green Roof is home for plants with special adaption to extreme site conditions and high regeneration capacity. Additionally, it is characterized by moos, succulent (Sedum), and small herbaceous plants including drought tolerant grasses. Thus extensive Green Roof require low maintenance and have no permanent installed irrigation system, because it would defeat the purpose.
Typically, the system depth for an extensive Green Roofs rages from 4 to 6 inches (10 cm to 15 cm). Although there are shallower extensive Green Roof systems on the market, they are only resilient in specific climate zones. E.g. temperate climate zones with Gulf Stream influence, like northern Europe. Because of the shallow profile, extensive Green Roofs also add less weight to a structure than deeper system.
In general, the weight of any Green Roof system is not a quality criteria. In fact, plants do not care about the weight. After all, plants care about the porosity of materials, Air-to-Water Ratio, and nutrient exchange capacity to name a few. Since all Green Roofs are supposed to retain water (for the plants), the weight of a system mainly depends and varies on the amount of water within the system. The specific weight of water is the same around worldwide.
The vegetation on extensive green roofs is subject to natural reshuffling. Plant species migrate or new plants species settle. If there is the desire to retain or keep a certain vegetation palette, a specific vegetation pattern or a regular full-scale flowering of its vegetation, additional maintenance efforts are necessary with an appropriate supply of nutrients. Sedum-only extensive green roofs require 50-80% more maintenance than a divers extensive greening with natural vegetation dynamic.
Over all, the natural vegetation dynamic creates biodiversity and makes extensive Green Roofs more resilient to Climate Change.
Comparison of Green Roof Types
|Green Roof Type ➡️|
8 to 30 inches +
45-160 Lb/sf +
|Max. Rain Event|
|Solar Garden Roof||
in amenity space
|Blue Green Roof||
Green Roof Technology