Division C - Accepted Materials
Group - Vegetated Roof Systems
Hydrotech Extensive Garden Roof® Assembly
by Hydrotech Membrane Corporation
| Material Acceptance and Product Details
The information published in the RCABC Roofing Practices Manual and offered below does NOT represent a complete set of the manufacturer’s data or specifications, nor is this material recommended or endorsed by the Guarantor. The preparation of a detailed specification is the responsibility of the Design Authority.
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- Vegetated Roof System Manufacturer
- Hydrotech Membrane Corporation
- Accepted for the RoofStar Guarantee Program
- October 25, 2024
- Accepted for application in
- Vegetated Roof Systems
- Acceptance Criteria
- Refer to the RGC Standard for Vegetated Roofs
- Manufacturer online resources
- Extensive Garden Roof Assembly
- System Summary
- The Extensive Garden Roof® Assembly is designed for locations that will receive little maintenance or where structural capabilities are a concern.
The Extensive Garden Roof is not intended for recreational use and is typically chosen for its appearance or to help reduce the "urban heat island" effect and minimize stormwater run-off. Extensive vegetated roofs only require a shallow growing media depth, generally as little as
75 mm to 150 (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 vegetated 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.
Features of the Extensive Garden Roof Assembly:
- Depth of growing media between 75 mm and 150 mm
- Reduction and delay of stormwater runoff
- Attenuation of the urban heat island effect
- Minimal maintenance required
- Use on flat or sloping roofs
Vegetation options - Plugs, Sedum cuttings, InstaGreen® sedum carpet (See Conditions and Limitations below)
Typical Application:
An Extensive Garden Roof® Assembly can be applied to flat roofs and sloping roofs with a pitch of up to 12:12 (45°), provided the appropriate measures are taken to cope with the shear forces and soil retention. Extensive vegetated roofs are typically lightweight and can be installed over a variety of structures including metal roof decks.
(Adapted from the manufacturer's summary)
- System Depth
- 101.6 mm (4") to 203.2 mm (7")
- Growing Media Depth
- 76.2 mm (3") to 152.4 mm (6")
- Vegetation Profile
- varieties of sedums
- Suitable climate zones
- 4, 5, 6, 7A, 7B, 8
- System Components
- Instagreen® Carpet (Click here for the Technical Data Sheet PDF)
- Extensive Litetop® Growing Media (Click here for the Technical Data Sheet PDF)
- Litetop® Filter (Click here for the Technical Data Sheet PDF)
- Gardendrain GR10 or Gardendrain GR25 (Click here and here for the Technical Data Sheet PDFs)
- Root Stop Standard (Click here for the Technical Data Sheet PDF)
- Root Stop Tape (Click here for the Technical Data Sheet PDF)
- GardenEdge® (Click here for the Technical Data Sheet PDF)
- Conditions and Limitations
- Note that system thickness is dependent upon the selection of components, which is determined (in part) by design parameters, including hydrological requirements. Consult with the vegetated roof system manufacturer for options and saturated system weight.
- Also note that vegetation coverage under the RoofStar Vegetated Roof Guarantee applies only to extensive systems planted with mats or trays - see Part 3 of Division A for more about coverage.
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