The intensive green roof

For most people, intensive green roofs are the type of green roofs they envision. However, the requirements for intensive green roofs must be checked very carefully. The roof construction itself can be a reason why this type of flat roof greening cannot be carried out. Below you will find useful information about intensive green roofs.

Subdivision into extensive and intensive green roofs

The intensive green roof is in contrast to the extensive greening of flat roofs. Up to a construction height of the required substrate of 15 cm is an extensive green roof. Above that, i.e. from a substrate height of 15 cm, one can generally speak of an intensive green roof. However, you can also subdivide the intensive green roof further.

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  • Intensive greening
  • simple intensive greening

The maximum intensive green roof

The intensive green roof is the most distinctive form of green roof. In individual cases, trees are used in addition to bushes and various shrubbery trees.

The intensive green roof is characterized by a high construction height

The construction height of the substrate starts at at least 25 cm. However, this already means that the roof load increases enormously. After all, the flat roof not only has to bear the additional weight of the substrate and the plants.

An enormous weight load is part of it

The substrate also acts like a sponge that stores all moisture (rain, melt water) until it is saturated. With a conventional flat roof, the roof drainage ensures that the load limits only have to be maintained for a very short period of a few minutes.

The roof load is built up massively

With intensive green roofs, on the other hand, it means a permanent additional load that the roof structure has to bear. This load is over 3.0 kN / m². In comparison: with extensive flat roof greening, the load is at least 0.5 kN / m², which is significantly less.

The simple intensive green roof

Accordingly, there is still the simple intensive greening between the extensive and the intensive greening. With this green roof, the substrate height is 15 to 25 cm. Even this green roof is still suitable for a variety of woods, shrubs and other plants.

The roof load of the simple intensive green roof is lower

However, the load on the flat roof is significantly lower than that of intensive green roofs. It is between 1.5 and a maximum of 3.0 kN / m².

Structural requirements for intensive greenery

Basically, you can divide flat roof structures into two different roof types.

  • Warm roof
  • Cold roof

The cold roof and intensive greenery

The cold roof is ventilated from the rear. This means that after sealing, a possible separating layer and insulation, a rear ventilation layer follows (from outside to inside), i.e. a pure air layer. This significantly weakens the statics of the cold roof. As a result, many cold roofs are not suitable for intensive green roofs.

The warm roof and an intensive green roof

The warm roof, on the other hand, has no rear ventilation, i.e. no air layer that would represent a static weak point. This means that in principle the prerequisites for warm roofs are better for carrying out intensive green roofs.

Effort and disadvantages of the intensive greening of flat roofs

Of course, the benefits far outweigh the benefits. This includes points such as sound and heat insulation, drainage effect and water storage, a good microclimate, positive influence on solar radiation and many other factors. However, there are also disadvantages to intensive green roofs. These can be seen in particular in the maintenance of the greenery.

  • Plants need to be cut back
  • adequate irrigation must be provided

In principle, you can imagine an intensive green roof like your conventional garden. You also have to water this regularly and prune plants. Before installing an intensive green roof, you must be aware that you will need to take care of it. In particular, the need for irrigation is very high, since the greening is an independent system.

Tips & Tricks In Germany, intensive green roofs are partly carried out by the state, the federal states and the city or. Community administrations promoted. You can find out more about this from the responsible building authority.

A green roof is usually subject to approval. Static calculations and a construction plan must be drawn up. So you have to call in a structural engineer anyway, who checks the flat roof for suitability for a green roof.