A blue roof is a sustainable drainage system that attenuates and manages stormwater at roof level, enabling controlled discharge in line with SuDS strategies.
Blue roofs are engineered flat roof systems designed to attenuate and control stormwater at source, providing a managed discharge into the wider drainage network. By temporarily storing rainfall and discharging it at a controlled rate over a 48 hour period, they support sustainable drainage strategies (SuDS) in response to increasing rainfall intensity and urban runoff.
As climate change drives more frequent and severe storm events, conventional drainage systems are often unable to cope with peak flows, contributing to flash flooding. Blue roofs mitigate this risk by reducing immediate runoff, extending discharge periods and alleviating pressure on below ground infrastructure. Their integration into roof design enables effective water management at roof level, particularly in dense urban environments where traditional SuDS features may be constrained.
System design typically incorporates flow control outlets, attenuation layers and waterproofing build-ups configured to achieve specified discharge rates in accordance with project requirements. Structural design must consider temporary stormwater loading associated with attenuation, with the roof deck and supporting structure designed accordingly. Coordination between waterproofing, structural and drainage disciplines is essential to ensure system performance and long-term reliability.
Design and specification should align with BS 6229, which provides guidance on flat roof drainage, falls and outlet positioning. Blue roofs are frequently used as part of a wider SuDS approach, often in conjunction with a green roof, supporting compliance with planning requirements while delivering a robust, engineered solution for controlled water management at roof level.
For project enquiries, general guidance, or pricing requests, please contact us via email or phone. Our team is here to help!
