Blue Roofs

The Aquamodul® blue roof system range is an innovative, sustainable drainage method specifically designed to attenuate and manage stormwater on flat roofs.

Traditional flat roof drainage design principles state that all rainwater should be removed from the roof construction as quickly as possible. However, rainwater management within urban areas is becoming more critical due to the effects of climate change increasing the risk of flooding within our communities. As these effects become more apparent, this traditional drainage design method is increasingly being challenged.

As defined within BS 6229:2018 Flat roofs with continuously supported flexible waterproof coverings – Code of Practice, a blue roof is a “roof designed to attenuate the rate at which rainwater is drained from the roof and is allowed to enter the drainage system”. A blue roof is not rainwater storage on a roof.

A blue roof provides source control, managing rainfall where it falls by temporarily attenuating it on a roof. It mimics the natural environment by managing the discharge of rainwater from roofs at a controlled rate in line with a drainage strategy and overall site flood risk assessment. They are becoming a common approach to deliver Sustainable Drainage Systems (SuDS) and manage local flood risk, particularly in dense urban environments where space is at a premium.

Aquamodul® and Aquamodul Oasis® blue roof systems are bespoke site-specific solutions that include a combined drainage and attenuation void within the roof or podium construction, with an outlet system designed to release the attenuated water at a controlled discharge rate. Aquamodul® and Aquamodul Oasis® blue roofs can be used beneath a multitude of different surface finishes including living roofs, solar PV and multi-functional mixed amenity finishes, or combinations of them all.


Compliant with BS 6229:2018 – Code of Practice (section Designed and engineered in compliance with the NFRC Technical Guidance Note for the construction and design of Blue Roofs. Compliant with CIRIA SuDS manual 2015, British Board of Agrément (BBA) Certificate 15/5222 Axter Force® Dalle RBM system, and European Technical Approval (ETA) Certificate No ETA-03/0049 Axter Wilotekt®-Plus hot melt system.


The Aquamodul blue roof insured system guarantee provides minimum 20 year cover for materials, design and workmanship of the accredited installer.

Find out more about Aquamodul® and Aquamodul® Oasis blue roof systems below.


  • Attenuates stormwater to alleviate localised or downstream flooding
  • Provides attenuation capacity within the roof or podium structure – eliminating the need for expensive underground attenuation tanks
  • Mitigates the effects of climate change
  • Typically attenuates up to 120mm of stormwater that is slowly discharged from the roof over a 24 hour period.
  • Rainwater outlet design ensures calculated rainwater out-flow rates for the site are achieved
  • Assists with planning and development applications
  • Sustainable drainage system (SuDS) compliant
  • Simple installation and maintenance
  • Site specific hydrology calculation designed and guaranteed by Axter
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