Green rooftop

  • Gründach extensiv

    green rooftop

Definition green rooftop

A green rooftop indicates the vegetation on a rooftop. It is differentiated between two types of greening: the extensive and the intensive greening, that can be used depending on the load capacity of the roof structure.

The extensive greening is a near-natural installation, that is able to obtain itself and doesn’t need any further care. There are used herbals, moss and grasses that don’t need watering. This kind of greening is also possible on rooftops with a certain slope.

For the intensive greening, a rooftop garden will be built. The laborious planting can consist of shrubs, bushes and even trees. These need intensive care and watering. A combination with terrace elements and accessible paths is customary. With this kind of greening, the load capacity of the structure is to be considered.

Why should I build a green rooftop? What are the advantages?

The advantages of green rooftops not only lay in the optics and the potential use as a rooftop garden in the city. In the countryside and with industrial buildings green rooftops are also advisable to stop the repression of nature.

Green rooftops improve the microclimate and function as dust filters. They offer compensation living space and help the biodiversity. With the drainage system can be purged the excess water after rainfall. As a protection of the rooftop against extreme temperature it prolongs the durability.

What does a green rooftop weight?

There are two options:

The light option weights 70 kg/ m2 (the weight aligns with the used granulate and substructure)

The standard option weights 100 kg/ m2 (the weight aligns with the used granulate and substructure)

Which option is the right one for you aligns with the substructure and the load capacity.

What type of green roof is the best for me?

If you choose an extensive or an intensive greening is on the one hand depending on the possibilities of the roof structure (load capacity, slope, form) and on the other hand depending on personal taste and the demands, that you have for the greening. For inspiration you can find different reference projects on our partners website.

What does a green roof cost?

The costs depend on the overall area and the kind of greening. You can calculate with 40 – 50 €/ m2 plus added value tax. The bigger the area, the lesser the costs per m2.

Is there financial support?

There are numerous financial supports for the rooftop greening. You should check the different funding programs on suitability for your project and pay attention to the deadlines.

What do I have to consider while planning a green rooftop?

First and foremost, you have to consider the substructure of the rooftop. Especially for the intensive greening. If you are planning a new building, you have to include the load capacity of the green roof. If you are adding a greening later, you should arrange a meeting on site to let the professional check out the rooftop structure and choose the greening accordingly.

The regulations regarding green roofs are helpful in the planning phase.

Green roofs and drainage

The excess water is led to the gully through the drainage layer of the greening structure. The rooftop drainage takes place then in the same manner as on a normal rooftop (via inboard or external pipes). An area with ca. 200 – 300 m2 can be connected to a gully with an opening width of DN 100. Every rooftop needs one gully and one emergency spillway at least.