Blue Roof Drainage

Rooftop areas (including podium decks) provide valuable, usable space on urban schemes and the modern approach is to use these spaces to benefit the wider development. These areas can be used to replace habitats which would otherwise be lost, enhance biodiversity and provide important public amenity and green spaces in city centres.

In the case of blue roof systems, which can be utilised at podium and roof level, they also support a good SuDS compliant design, providing attenuation and controlled discharge of stormwater. As such, ABG’s blueroof and green roof systems can contribute significantly towards meeting BREEAM or LEED sustainability criteria.

Blue Roofs are designed to attenuate / slow rainwater discharge as opposed to traditional roofing drainage, whereby it is designed to drain away as quickly as possible. ABG blueroof allows the rainfall to be attenuated within the roof build-up before discharging at a defined, controlled rate. This is particularly beneficial on tight urban sites where installation of other attenuation techniques such as ponds or below ground / basement tanks are not feasible.

ABG blueroof system animation

ABG specialise in the design, supply and installation of a wide range of blue roof systems, compatible with a number of different roof types (i.e. inverted, warm roof, uninsulated and podium decks) and surface finishes (green / biodiverse roof, amenity areas with either paving, decking or play areas, and mechanical / solar PV plant). This typically includes everything above the waterproofing system; from attenuation systems, drainage & reservoir layers (e.g. Roofdrain) to insulation, growing media and vegetation layers (such as sedum and wildflower).

Blue roofs contribute significantly to good SuDS design, either with or without a green roof finish. They work by providing temporary storage of stormwater and controlling discharge in line with site planning conditions. Similarly to green roofs they are suitable for implementation on both new-build and retro-fit developments, flat roofs or podium decks with either a warm or inverted roof build up.

Typical applications

  • Podium deck drainage
  • Drainage layer beneath block paving
  • ‘Blue Roof’ attenuation systems at roof & podium levels
  • Roof garden finishes and materials such as soft and hard landscaping and reservoir / drainage boards for Extensive & Biodiverse Roofs


  • Management of stormwater ‘at source’
  • Habitat replacement and enhancement
  • Creation of valuable amenity space
  • Significant contribution towards achieving BREEAM and LEED sustainability points
  • Protection to the waterproofing system, therefore extending its overall design life
  • Quick and easy installation to minimise programme time
  • Robust materials to resist installation damage
  • The complete system from design to installation and on-going maintenance

A blue roof can accommodate a wide range of surface finishes whilst also forming an integral source control and attenuation element within the SuDS design on modern developments, often eliminating the requirement for storage capacity in other areas of the site.

Like green roofs, blue roofs are suitable for use on a wide range of substrates and are compatible with most modern waterproofing systems. They are also flexible when it comes to the roof build up, being equally as effective on an uninsulated podium construction as they are within a warm or inverted roof construction.

The ABG blueroof system has been used extensively across many leading sustainable developments across the UK (click for recent Blue & Green Roof Projects) and ABG Geosynthetics offer a complete green and blue roof service; including design, installation and on-going maintenance contracts via our sister company ABG Installs.

Podium drainage during and after construction

Blue / green roofs

Urbanisation and development of land creates hard impervious surfaces that absorb only 5% of rainfall, leaving the remainder to run-off into both natural and man-made water systems which struggle to cope with the volumes. This has been highlighted in recent flooding events occurring all over the country.

Green roof surfaces can play an important role in mitigating these events, with as much as 95% of rainfall absorbed into the vegetated surface, especially when designed as an integral element of a sustainable urban drainage system, also known as SuDS. SuDS design demands that water falling across a development site is not simply channelled into stormwater drains and discharged into the local river. Instead the drainage is designed to mimic that found in nature where water is attenuated, treated and infiltrated through natural processes.

Typical Client Profile

  • Building Owners & Developers
  • Landscape & Main-Build Architects
  • Civil, Public Health & Structural Engineers
  • Main Contractors, Landscape & Roofing Contractors

Project Attenuation Calculations

Submit your project design request via our Design Solutions form.

Case studies

Additional information

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