The Extensive Garden Roof® Assembly is ideally suited for locations that will receive little maintenance or where structural capabilities are a concern.
Extensive Garden Roofs are not intended for recreational use & are usually chosen for their appearance or to help reduce the "urban heat island" effect & minimize stormwater run-off. Extensive roofs only require a shallow growing media depth, generally as little as 3"-6", & therefore add little weight to the roof structure below when compared to a standard ballasted PMR roof.
Recommended plant types for extensive roofs need to be drought, wind & frost resistant, such as self-generating sedums, herbs, grasses & other vegetation that can withstand harsh growing conditions.
The water stored in the growing media & drainage/retention layer is sufficient to sustain the drought resistant plants between periods of normal rainfall. Thinner assemblies & very lightweight growing media blends are available for Extensive Garden Roof Assemblies.