Sedum Extensive Green Roof Systems
Extensive green roof systems are designed to support low-growing vegetation types such as sedums, grasses, mosses, and selected wildflower species.
These systems typically require minimal substrate depth and are generally selected for visual integration or ecological enhancement, subject to project-specific requirements. Vegetation used in extensive systems is suited to lower nutrient environments and may require limited irrigation depending on climate and exposure. System selection should be based on validated horticultural data and site-specific conditions.
Sika® NatureRoof Sedum Extensive Green Roof Systems
Sika® NatureRoof Sedum Extensive Green Roof systems replicate the aesthetics and biodiversity benefits of a ground level Sedum meadow at roof level, have a long flowering window and are compliant with building regulations fire performance requirements (BRoof(T4) and the GRO Code of Best Practice.
Key System Features
- Dry weight: 71 kg/m²
- Saturated weight: 107 kg/m²
- Build-up: 110 mm
- Rainfall retention: 50–60%, storage up to 40 l/m²
- Suitable for roofs: up to 45° pitch
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A Sika® NatureRoof Sedum Extensive Green Roof system will typically have a dry weight of 71 kg/m2 and a saturated weight of 107 kg/m2 with an overall build-up height of 110 mm above the roof system. It is installed with a level low organic material growing medium to a minimum settled depth of 80 mm over a 25 mm deep water retention and drainage layer with filter fleece.
Planting is commonly achieved using either Sedum and Sedum Plug Plants that are available in a variety of species to provide greater plant diversity and flexibility for shaded or sunny areas, or through the casting of Sedum seeds which are available in a variety of seed mix options. Pre-grown Sedum blankets with a minimum 75% plant cover are also available for more instant plant cover. Sedum and Sedum Plugs, or Sedum seeds, will take 12 to 18 months to achieve circa 60% to 70% plant cover with full cover taking up to 4 years.
Suitable for flat roofs and zero falls’ roofs, Sika® NatureRoof Sedum Extensive Green Roof systems can also be installed on roofs up to 45 degrees pitch, or on waived, curved or domed roofs.
A Sika® NatureRoof Sedum Extensive Green Roof is installed on-site using individual components to create each layer. Green Roof systems should be installed by suitably qualified individuals holding LANTRA or GRO installation qualifications. When installed by a Sika® NatureRoof Registered Contractor the green roof system forms part of the comprehensive Sika roof guarantee.
Sika® NatureRoof Sedum Extensive Green Roof systems provide positive contribution to rainfall management, retaining approx. 50% - 60% of rainfall depending on saturation level and up to 40 l/m2 of permanent water storage. As this retained rainwater evapotranspirates, the green roof contributes to the cooling of the urban environment, as recognised by the House of Commons Environmental Audit Committee inquiry in 2024 into Heat resilience and sustainable cooling, which led to a recommendation that Government legislate for the use of Green Roofs in cities across the UK.
Sika® NatureRoof Sedum Extensive Green Roof systems should be maintained twice annually, at a minimum, in the Autumn and early Spring. This should include cutting back to a low level to support new growth and spread seed heads, creating a self-sustaining plant community. All grass cuttings and other organic matter must be removed to ensure increased fire load risk at roof level over time. Unwanted plant species such as grasses, buddleia etc. should also be removed.
Solar PV panels can be incorporated within a Sika® NatureRoof Sedum Extensive Green Roof system creating a BioSolar system that is compliant with the requirement of the Department for Education (DfE) schools’ output specification. The inclusion of solar PV panels with the green roof enhances the power output of the PV system due to the evapotranspiration of moisture from the green roof. This cools the panels, whilst the green roof also reduces the solar gain experienced by traditional exposed waterproofing. Sika® NatureRoof PV Green Roof systems are designed in accordance with the GRO BioSolar Best Practice Guide with the solar panel systems installed by Sika® SolarRoof Registered Contractors.
Sika® NatureRoof Sedum Extensive Green Roof systems can be installed over a Sika® RetentionRoof Blue Roof system for enhanced rainfall management contribution to a site-specific Sustainable Drainage System (SuDS).
System Components
Sedum Extensive Green Roof Systems - FAQs
There are hundreds of Sedum species but only 6 species are UK natives: Sedum acre (Biting Stonecrop), Sedum album (White Stonecrop), Sedum hispanicum (Spanish Stonecrop), Sedum rosea (Roseroot), Sedum telephium (Orpine), and Sedum reflexum (Reflexed Stonecrop).
Green Roof growing medium or substrate is delivered in either sacks or bulk bags. Sacks will come on a pallet and bulk bags will require a crane lift to the roof.
Sedum blankets are rolled up at the nursery and shipped as rolls on a pallet, much like lawn turf.
The Sedum blankets should be unrolled within 24 hours to prevent plant death due to organic heat.
Sedum Green Roofs will need irrigation if installed during a warm month. Permanent irrigation will not be required unless the roof is on a slope or is pitched.
