Content
- Green roofs: the piece of extra gardening on the roof
- Against all prejudices: green roofs as a small project
- Extensive roof greening: not only easy to maintain
- Careful planning - the "A and O" for green roofs
- Planting options for extensive green roofs
Rooftop plants cool in summer and isolate in winter
Green roofs: the piece of extra gardening on the roof
Thirty years ago, the Austrian artist, architect and environmentalist Friedensreich Hundertwasser predicted that the forest, the green field or the lavish vegetable garden on the roof would soon be taken for granted.
Green roofs can double the durability of the roof
Green roofs as roof coverings of the future are actually no longer a romantic daydream, because nature is on the way to return to the city. They increase our quality of living, allow rainwater to evaporate better and also exert a positive influence on the climatic conditions. Green roofs cool the houses in the summer, isolating them in winter and their construction is even financially supported. The garden journal has just published a detailed article on the technical and organizational details of green roofs. And yet, most homeowners are still skeptical.
Against all prejudices: green roofs as a small project
Among the most common objections of the property owners are fears that a natural green roof could be damaged by the plantings and such projects too expensive and would be too expensive from the design effort. Ergo: Just try the extensive greening of the equipment shed, the doghouse or the birdhouse! And as far as the reduced durability of rooftops is concerned, the Association of German Roof Gardeners e. V. anyway better and analytically verifiable: "The durability of a (bare) flat roof is even with professional execution on average only 15 - 25 years" *. And: "Numerous green roofs from the 1970s prove that expertly designed green roofs can easily double the life of the waterproofing system." *
Extensive roof greening: not only easy to maintain
Green roofs fit well into the landscape
This method of a total of three types of green roofs is also optimal from the static load capacity, especially for lightweight roof structures. In addition, the extensive greening usually comes without additional irrigation. Nearly all professionally sealed roof constructions (flat, saddle, pulpit roof or tonneau roof) are suitable for greening, provided the structural specifications are taken into account. For roofs without a slope, wet drainage elements must also be provided so that the plants are not damaged even during extensive rainfall.
Careful planning - the "A and O" for green roofs
A careful design planning is not only crucial for the subsequent care and the expected costs, but also has optical effects that must be clear before the first wheelbarrows with gravel, substrate and perennials are heaved on the house roof. So:
If you are unsure yourself, do not hesitate to ask for expert advice on any questions and problems that may arise. On the portal of the German Dachgärtner Verband e. V. you will find current address material from experienced roof gardeners from your region as well as relevant specialist dealers, manufacturers and associations that support and accompany your green roof project.
Planting options for extensive green roofs
Not all plants are suitable for green roofs
Undemanding and drought-resistant plants, which manage with a relatively thin and thus light substrate layer, are particularly well suited for this purpose. Ideal roof pitches are between 2 and a maximum of 15 percent, which can withstand a total weight of about 120 kg per square meter of roof area without damage. Ideal are plants with as small and flat root ball or pre-cultivated plant mats. In addition, there is also the green roof from the bag. In addition to easy-care grassland plants, they usually contain different sedum and Sempervivum species, which suffice for sowing on a three to four square meter roof area. Here are some planting ideas of the DDV in tabular short form:
Source: German Dachgärtner Verband e.V.
Finally, sprinkle all or part of it and sit back comfortably, because the work is done. You will hardly have to worry about the new green roof in the future and, above all, keep your hands on the watering. The settlement and spread of unwanted weeds would only be fueled. From time to time only the spreading seedlings need to be removed from the roof, much more is not for you to do.
* Quote from: DDV practice guide "The 1 x 1 green roofs" by the German Dachgärtner Verband e. V., Nürtingen, 2019.