The Extensive Garden Roof® Assembly is ideally suited for locations that will receive little maintenance or where structural capabilities are a concern.
Unlike Intensive Garden Roof Assemblies, Extensive Garden Roofs are not intended for recreational use and are typically chosen for their appearance or to help reduce the "urban heat island" effect and minimize stormwater run-off. Extensive roofs only require a shallow growing media depth, generally as little as 3"-6" (depending on the region), and 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 and frost resistant, such as self-generating sedums, herbs, grasses and other vegetation that can withstand harsh growing conditions.
The water stored in the growing media and drainage/retention layer is sufficient to sustain the drought resistant plants between periods of normal rainfall. Thinner assemblies and very lightweight growing media blends are available for Extensive Garden Roof Assemblies. Contact us for specifics.
An Extensive Garden Roof Assembly can be applied to flat roofs and sloping roofs with a pitch of up to 12:12 or 45°, provided the appropriate measures are taken to cope with the shear forces and soil retention. Extensive roofs are typically lightweight and can be installed over a variety of structures including metal roof decks.