Green roof guideline - what does it say?

The term "green roof guideline" is used quite often, but hardly anyone knows what this guideline says and by whom it is drawn up. In this article, these knowledge-based gaps are closed.

The green roof guideline

The Research Society for Landscape Development and Landscaping e.V., which is also called FLL for short, is a registered association based in Bonn, which has been dealing with questions of landscape construction and landscape development on a scientific level since 1975.

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The so-called green roof guideline is also adopted by the FLL, which deals with all aspects of green roofs, with the correct and optimal structure, maintenance and correct planning of green roofs.

The FLL green roof guideline is regarded by all experts as practically binding, even DIN refers to the guideline in many cases. If you want to green your roof, you cannot avoid the requirements of the directive.

Especially when it comes to the correct roof structure, you should absolutely adhere to the specifications.

The individual layers in the roof structure according to the FLL (from bottom to top)

  • Separating layer
  • Protective layer
  • Rooting layer
  • Drainage layer
  • Filter layer
  • Vegetation layer (with extensive greening usually two layers)

Additional Relevant Guidelines

In addition to the requirements mentioned in DIN, there is also an important guideline with regard to green roofs.

These are the so-called flat roof guidelines, more precisely the "guidelines for the planning and execution of roofs with waterproofing" of the central association of the roofing trade. There, too, reference is made to green roofs and the necessary requirements.

When planning a green roof, you should definitely also involve an experienced roofer, as the high possible roof loads, which in some cases can be well over 60 kg per square meter, definitely require a professional assessment.

Tips & Tricks Make sure that you can only install extensive green roofs on some roof types and that you may need additional drainage on others.