Introducing BluRoof: Sustainable Engineered Drainage

Posted by david.luukas

BluRoof LogoIntroducing BluRoof: A Sustainable Engineered Drainage System from Alumasc.

BluRoof is a new ‘systems approach’ to Blue Roofs – an increasingly prominent sustainable drainage technique that switches the focus of rainwater management from instantaneous runoff of high intensity storm events to controlled, attenuated runoff.

Bluroof Drainage 3d

Simon Poë, Technical Director for Alumasc Roofing Systems, explains the need for these advances in rainwater drainage.

The recent increased frequency and severity of flooding in the UK has served to highlight the need to complement conventional drainage systems with a range of sustainable measures that can provide additional drainage capacity.

Blue Roofs are a relatively inexpensive option as, unlike most other SUDS tools, they occupy otherwise-redundant roof space without extending beyond the building’s footprint.

A Blue Roof is designed to alleviate flood risk by reducing and controlling the peak rate of discharge in compliance with design requirements; facilitating the detention of stormwater, up to a prescribed maximum hydraulic head, for subsequent discharge over an elongated period of time.

Alumasc’s BluRoof system combines the new Harmer BluRoof outlet with a high performance BluRoof waterproofing membrane.

How does the Harmer BluRoof Outlet work?

The Harmer BluRoof outlet restricts the maximum


permissible discharge of stormwater from the roof. As a result, during more intense storm events, rainfall will exceed the rate of discharge, leading stormwater to temporarily back-up on the roof until such time as the Harmer BluRoof outlet has the capacity to discharge it.


Clearly, the temporary storage of water at roof level requires the highest confidence in the waterproofing solution. Alumasc Roofing Systems has developed its BluRoof solutions based upon tried and trusted systems, with yet further enhanced specifications and service levels. For insulated roof areas, the dual-reinforced BluRoof Built-Up High Performance Membrane is specified as a fully-bonded system, with extended and high pressure-rolled laps for excellent watertight integrity. With a proven track record of over 40 years, the system offers a mineral-free surface which reduces the risk of blockages, whilst a root-resistant version is also available, for compatibility with Blackdown Green Roof systems, available from Alumasc.

For buried (non-insulated) systems, such as podium applications, Alumasc’s BluRoof Monolithic Membrane provides a self-healing waterproofing solution that is free from laps and with a proven track record of over 50 years.

BluRoof Response

A Blue Roof can contribute to the attenuation of the kind of storm event that can induce localised flooding. For example, in response to a 6 hour storm event with a return period of 1 in 100 years, when rainfall depth is 109 mm, and a peak intensity of 5.01 l/s falls on a 284 m2 roof, the peak rate of runoff is 0.285 l/s. This represents a peak reduction of 94%. In this case, the maximum stage of water reaches 90 mm, before draining slowly over a period of 27 hours.

The engineered drainage approach adopted within Alumasc’s holistic BluRoof solutions, which includes enhanced service levels for specification and site support and leak detection testing, enables Alumasc to offer a single point warranty that covers the waterproofing and drainage as part of its “BluRoof Promise”.

To view our video about the BluRoof Stormwater Management System click here.

To download the BluRoof Brochure click here

To arrange a BluRoof seminar click here

For further information contact us.

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White House Works, Bold Road, Sutton, St Helens, Merseyside, WA9 4JG