Blue Roof Systems

Rooftop sustainable urban drainage solutions (SuDS)

The development and expansion of towns and cities has seen exponential use of impervious surfaces causing artificially high rates of rainwater runoff. In measures to prevent flooding, planners are restricting the amount of rainwater leaving a site via the drainage system which can be limited to 5-10 litres per second per hectare, the same flow rates for regional greenfield sites.

What is a blue roof?

A BauderBLUE roof controls rainwater where it lands, one of the core pillars of SuDS design. The blue roof outlet restricts the discharge of stormwater to a calculated and defined flow rate to significantly slow down the volume of water leaving the site. As the storm passes, water continues to discharge from the roof at a controlled rate over a set period (typically 24 to 48 hrs). 

There are different options available to the construction designer to achieve a blue roof depending on the finish desired and the volume of water to be attenuated.

When to specify...

This rooftop SuDS solution has weight load implications and the project’s structural engineer will need to be engaged at an early stage. A BauderBLUE roof system can be constructed at either rooftop or podium level with a variety of landscape finishes including green roofs, biosolar PV array, or hard landscaping such as promenade tiles. Our three solutions can be incorporated in warm, cold, and inverted roof designs. Blue roofs are usually required to meet planning when restrictions have been placed on the construction to limit the flow rate of rainwater leaving a site via the drainage system. 

Key features

  • Bespoke, project specific discharge rates to match the requirement of the drainage requirements for the site.
  • Precise volume and weight of water storage with overflow to ensure the maximum water level (H-Max) is never exceeded.
  • Design support to meet british standard and blue roof guidance criteria.
  • BBA Certificate 10/4744 for Bauder Total Green Roof System and 06/4350 for Bauder Hot Melt System.
  • Following the National Federation of Roofing Contractors blue roof guidelines.


  • Three different soultions with simple low maintenance design.
  • Our specifcation service will confirm suitability of waterproofing system for each roof area.
  • Warm, cold, and inverted roof design options.
  • Single point guarantees to comply with insurancre company requirement.

Waterproofing a blue roof

Contact us today about your project

Each project is unique in its requirements, but we have case studies and examples of our work available to help guide you. If you are looking for a particular roof system, then get in touch with our team to discuss your project’s individual needs.

Categories  STORMsub STORMcell STORMvoid
Controlled discharge flow rate X X X
Inbuild overflow X X X
Paving finish   X X
Green roof finish X X  
Multiple surface finishes   X  
Low-cost option     X
High volumes of water storage   X X
Suitable for inverted blue roofs X X  
Highest ecological value X    
Non-combustible build-up     X
High compressive strength   X  
Low profile blue roof X   X

It is critical to ensure the waterproofing system is able to meet the demands placed on it by the blue roof. Additionally, the design should minimise the risk of water ingress by eliminating penetrations within the blue roof areas.