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.

Features of the Extensive Garden Roof Assembly:

  • Depth (3” - 6” of growing media)
  • Reduce and delay stormwater runoff
  • Help to mitigate the urban heat island effect
  • Requires minimal maintenance
  • Can be used on flat or sloping roofs
  • InstaGreen® GT-4 Tray available for modular applications
  • Vegetation options - plugs, cuttings, InstaGreen® Sedum Carpet or InstaGreen® Sedum Tile

Typical Application:

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.

Recent Press

  • May 21, 2018
    American Hydrotech, a recognized leader in the development and distribution of premium waterproofing and roofing assemblies, today announced the availability of their Protected Membrane Roof (PMR) Planning Guide , a unique, new resource representing...
  • February 1, 2018
    CHICAGO, ILLINOIS (February 1, 2018) The Chicago Blackhawks have captured the hearts of the city of Chicago along with three Stanley Cups in the last decade. The Blackhawks routinely lead the league in attendance at the United Center, and fans were...
  • October 18, 2017
    CHICAGO, ILLINOIS (October 11, 2017) American Hydrotech – a market leader in the development and distribution of premium waterproofing and roofing products and assemblies, today announced the introduction of the InstaGreen® GT-4 pre-vegetated tray,...
  • April 3, 2017
    Wind data is a critical issue to consider when building a new structure. An increase in the number of green roofs on buildings has driven a need for new wind design standards to be written for vegetative roofing assemblies. Richard Hayden discusses...
  • September 27, 2016
    (September 28, 2016) Washington State has always been considered a pioneer when it comes to the adoption of greener and more sustainable practices. One of the most sustainable practices is to reuse an already constructed building and enhance that...
  • July 16, 2016
    (July 16, 2016) Excerpt from an article in Forester Daily News Green roofs – also known as vegetated or garden roofs – are key green infrastructure elements and are being increasingly recognized for their “valuable ability to absorb, reduce, and...

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