The keys to success
Published in 2007 by the CSFE in partnership with Adivet, the UNEP and the SNPPA, the professional rules for the design and construction of green roofs filled a gap in the regulations as far as waterproofing and green roof build-ups were concerned.
An architect will be able to advise you on whether or not your project is feasible and propose a solution (new build or renovation). It is essential to take account of the nature of the support structure and the insulation and waterproofing membranes when designing a green roof. After that, the different parts of the green roof build-up (drainage and filter layers, substrate, plant species) will be chosen according to your expectations and the possibilities offered by the building in its environment (climate, exposure, roof pitch, etc.).
Climate: as it operates as an eco-system in itself, the roof vegetation will develop naturally in most regions of France. However, in arid regions (e.g. Mediterranean climate) supplemental irrigation will be indispensable. It is up to the designer/supplier of the green roof system to define what is appropriate to each situation (region, exposure, pitch, aspect, etc.).
The maintenance required on extensive green roofs is limited, but 1 to 3 annual inspection visits will still be necessary. This is, as for any roof, to check the rainwater outlets, clean the sterile areas covered with gravel, check that the plants are developing correctly and remove harmful species.