What is a blue roof, and how does it work?

Here at Enviroply Roofing, we are the North West’s leading commercial and industrial roofing experts. For warm roofs, cold roofs, single ply roofing systems, and green roofs, among others, we can provide all manner of roofing solutions. One type of roof we can design and install is the blue roof. But what is a blue roof, and how does it work? Well, this is our guide to everything you need to know about blue roofs.


What is a blue roof?

A blue roof is a roof design that is explicitly intended to control the release of water, typically rainfall, over time. In the North West, we see an incredible amount of rainfall annually, varying from area to area. In the Yorkshire Dales for example, you can expect 1550 mm of rain per year! Penrith follows close behind with 947 mm on average, and Blackpool and Manchester see around 850mm. In rural areas, this rainfall can easily be absorbed, but in built up areas in towns and cities, this rainwater has nowhere to go. This results in the dangerous levels of flooding we have seen over recent years. As a result, the blue roof is rising in popularity.

The design of the blue roof, means that water can be temporarily stored, treated and released in a controlled manner, directly into the sewers, waterways and river systems. This occurs over a 24 hour period, and it can help to alleviate the impact of water run off, onto concrete roads and pavements, helping to prevent flooding.

However, it is important to note that a blue roof is not to be considered as a water storage solution.

How does a blue roof work?

So how exactly does a blue roof control the release of water? How does this work? Well, a blue roof makes use of a specially engineered outlet. This is designed to restrict the release of rainwater, to a pre-calculated and pre-designed flow rate. So instead of water gushing off your roof, onto the impervious concrete below, the flow of water will instead be greatly reduced. The roof is designed to allow the water to be released over a 24 hour period, instead of the almost instant overflow you can expect with any other type of roof.

As the rain stops, or the storm passes, water will continue to be released from the roof, at a steady, controlled rate. This can help to prevent downstream or localized flooding.

Some types of green roof can also be classed as a blue roof, because of the way that the water is irrigated throughout the soil, controlling water run off. A hybrid version which combines the aesthetic and ecological benefits of a green roof, with the high-performance water-attenuating properties of a blue roof, can also be an option.

Would a blue roof be suitable for your property?

Blue roofs are suitable for a wide variety of building types, including industrial, domestic and commercial properties. Because the stormwater attenuation is designed to fit within the footprint of the building, this means that the blue roof is ideal for urban and built up environments, where ground space is limited.

Because of the weight of the water, a blue roof does have weight load implications, As a result, a structural engineer will need to work with the project from the beginning.

For more information about blue roofs, and what they can offer your property, get in touch with the experts today, here at Enviroply Roofing.