English: Schematic showing the setup of an intensive and an extensive green roof. For the thicknesses of the growing medium layer of both, we can make a distinction into 4 types[1][2]:
Extensive green roofs:
thickness range 1= 7,6 cm to 10,2 cm (suitable for sedums, herbs)
thickness range 2= 12,7 cm to 17,8 cm (sedums, herbs, perennials)
Intensive green roofs:
thickness range 3= 25,4 cm to 30,5 cm (perennials, grasses, shrubs
thickness range 4= 30,5 cm+ (grasses, shrubs, trees)
Note that only tickness range 1 and 4 are shown in the schematic. Thickness range 3 was not drawn out, as it seems to be only practical for when designing sod roofs (which are not accessible roofs). Thickness range 4 instead are true intensive green roofs which are accessible[3]
Note thate the membrane protection also works as root barrier, see this document, at page 2, it's marked as simply "root barrier" in the image
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