Land consumption and soil sealing caused by building activity have ecological consequences, which can be perceived more and more. According to reports of the German Federal Nature Conservation Agency, an area of approximately 90 hectares gets lost every day for the benefit of road construction and buidlings only in Germany; this is equivalent to the size of 150 pitches! Such, ecosystems - habitats for animals, plants and ultimately for people - are being destroyed every day. And more than this: sealed and destroyed soils cannot perform their tasks, which are extremely important for us; tasks like the buffering and transformation of components harmful to the environment, water storage and ground-water regeneration. Evaporation is reduced, the local climate turns drier and warmer.

Establishing of vegetation in populated areas cannot compensate these impacts caused by sealing and building measures. However, well-directed measures can revaluate the anthropogenic ecosystem "urban space" such that some relief concerning several aspects relevant to the environment can be achieved. Green roofs are one of these measures. They create habitats for plants and animals and attenuate the climatical and hydrological, but also aesthetical consequences of soil sealing. Vegetated roofs reduce and delay the discharge of recipitation water, and thus, produce cooler and more humid air in populated areas. Gray, dead roof scenery changes to green oases. And it is we people, who primarily profit from that!

Extensive Landscaping on Roofs?

Who does not know them: old, moss-covered roofs, small pads of stonecrop in a corner of the garage roof, the Sempervivum, apparently rooting no-where? They do exist, the specialists among the plants, which flourish without humus and soil, in smallest wall gaps and on thin accumulations of fly ash. We take advantage of the ecological demands of these specialist plants, which get along with a minimum of water supply, the leanest nutrient conditions and without soil. For extensive greening on roofs, we have procedures at our disposal, which allow us to establish a dense, flat vegetation rich in blossoms.

Not only common flat roofs, but also constructions like reversion roofs, 0°-roofs and more inclined roofs can be vegetated - an adequate construction presumed. As extensively greened roofs have no connection to the soil and as their load capacity is limited, the vegetation on the roof has to do with only little rooting space (from 5 cm upwards) and frequent water shortage. The roof as habitat is therefore an extreme site of a very special characteristic. Only when considering defined specifications and carefully applying available procedures, it will be secured that the plants are provided with the necessary minimum of precipitation water, root space and nutriants. Depending on the type of roof, differing single or multilayered constructions for establishing vegetation are required for this purpose. Competent performance turns roofs into wonderfully blooming oases! Apart from colourful herb meadows or perfumy lavender fields, florid sedum vegetations are extremely undemanding and especially pleasing, not only because of their blossoms, but also because of their reddish foliage throughout the whole year. Moss covers are of an individual beauty and a simple elegance.

Technical Solutions for Green Roofs

The different construction systems available on the market finally represent nothing more than a substitute of the natural soil layers with their specific soil-ecological tasks. Roof sealing and root protection assume the function of sediment layers and aquifuges, which are not rootable and pond the ground water. Drainage and water-storing systems take on the tasks, which aquifers from coarse-grained sediments perform in nature. Finally, the substrate can functionally be compared with the rootzone of a natural soil in which weathering processes take place.

A complete green roof system consists of root protection, drainage and water storage mat, filter mat, rootzone substrate layer, and finally the vegetation. Possibly, constructions with single or dual layers are sufficient to offer permanent advantageous growth conditions for a vital extensive vegetation.

Establishing and Maintaining Vegetation

Sedum sprouts, moss, seed and required components like slow-release fertilizers, soil binders and mulch are applied via hydroseeding. Several sedum and moss species are applied as living sprouts and plants as those are capable to generate rhizoms resp. rhizoides, provided that soil and ambient air are not too dry and not too warm. Sedum and moss vegetations are especially undemanding, easy to maintain and build very pleasing flower or foliage aspects. More elaborate and rich in species are intermixtures from grasses and herbs. On somewhat thicker substrate layers even more demanding phythocenoses can be established, which, however, are more cost-intensive and require more maintenance. If a particularly quick planting of vegetation is desired, you may use pre-cultivated vegetation mats, specially produced for planting vegetation on roofs.

As the roofs to be vegetated cannot be directly worked on from the hydroseeder, adequate hose extensions are necessary to reach even high roofs (e.g. roofs of office buildings or industrial facilities).

Apart from using appropriate plants, an effective soil binder is extraordinarily important as seed, sprouts, components and substrate grains must be fixed to resist the especially intensive winds on high roofs during germination and rooting.

We already mentioned, that extensive sedum vegetations are especially easy to maintain as irrigation is required only during the sprouting period and fertilization only from time to time and if necessary. However, unwanted periphyton ought to be eliminated in regular intervals. Connections and supplies need regular controls.

Planning, execution and maintenance of planting vegetation on roofs are regulated in the directive of the Forschungsgesellschaft Landschaftsentwicklung Landschaftsbau e.V. (FLL) (=Association for Research concerning Landscape Development and Landscaping).

BENDER Recultivation projects the planting of vegetation on your roof tailored to your object and mounts the appropriate system including the vegetation. Profit from our know-how and our long-term experience!

Advantages and Benefits of Extensive Landscaped Roofs Are Obvious

  • Cash incentives: Promotion of green roofs by towns and cities and local authorities
  • Decreasing sewage fees, stormwater- management
  • Heat and cold insulation, energy saving
  • Higher durability of roofs with vegetation
  • Sound adsorption and noise reduction
  • Improvement of the microclimate
  • Dust binding and improvement of the air quality
  • Mitigation of land consumption
  • Mitigation of sealing
  • New habitats for several plant and animal species
  • Aesthetic improvement of urban settlement areas