The drainage of the green roof

The drainage of an planted green roof is a complex construction. Legal requirements must be adhered to. Consideration behavior of planting, water donations and constipation by vegetation. The proper drainage should be mounted by professionals.

Ready-free dimensioning

In the planning phase of a green roof, the construction heights of the intended planting are adjusted. Depending on the thickness of the upper vegetation layer, the substructure must be dimensioned. On the root-resistant roof sealing, a drain layer is installed. About it lies the planted vegetation layer with the planting earth.

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The drainage system is adjusted in the amount of the processes the dimensions of the Gründachs. The flow volume is the second important factor. The drain channels and nozzles must not form a backwater. The water level must never rise to the height of the vegetation layer.

Guide systems and drainage layer

In addition to drainage channels and nozzles, full-surface water control systems can be mounted. They provide through more drainage points for a more uniform dewatering of the leachate. Water control systems consist of additionally between drain layer and vegetation layer inserted flow elements.

All drains and necks or gullys are separated from the ground of the vegetation layer with a lateral drainage structure of pebbles. This avoids earth laziness or the exciting openings. Another structural regulation is the installation of a control shaft.

Structural conditions

The entire green roof must have a gradient of at least 1.7 percent. Two to three percent are common. According to the fake direction, the processes are positioned. Moving the vegetation layer must be bent structurally. Loose earth surfaces must not be in the neighborhood of the processes.

There are grasps with single-layer extensives and multi-layer intensive green reasons. In intensive coatings, the drainage is also possible in several shift levels. Special substrate mixtures save leach water temporary. This decreases the necessary drainage performance.

Tips & tricks Due to tub-shaped drainage gratings, the statutory minimum construction height is lowered. This is especially necessary from doors. Exact regulations can be found in the flat roof guidelines of your construction authority.