In recent years, green roofs have risen in popularity and more and more architects and specifiers are embracing the concept of green roofs due to their ability to have a significant effect on a building’s sustainable credentials.

The term ‘green roof’ refers to a roof that is partially or completely covered with vegetation and a growing medium, planted over a waterproof membrane. It may include additional elements such as roof barriers, drainage or irrigation systems. Other features that can form green roofs include ‘container gardens’ where plants are maintained in pots, rooftop ponds and elevated open space areas that primarily form pedestrian routes on the roofs of lower level buildings.

Mastic Asphalt Roof GardenGreen Incentives

The concept of green roofs has been around for some time, with the first green roofs appearing in northern Europe. Countries including Scandinavia, Germany, Austria and Switzerland have a long tradition of using green roofs. In some countries, legislation has been introduced to encourage the installation of green roofs, with many German cities for example providing incentives for green roof installation. Around 10% of all German roofs are now green and in France a law has been passed dictating that rooftops on new buildings built in commercial zones must either be partially covered in plants or solar panels. In addition, every new build in Stockholm must incorporate a green roof. Outside Europe, Canada, USA, Japan and Singapore have all experienced growth in green roofs.

In the UK, the City of London actively encourages the installation of green roofs for their environmental benefits. They enhance biodiversity, reduce rainwater run-off, improve insulation, moderate the local climate, make buildings more attractive and provide amenity for residents who may not have access to private gardens. The City’s Biodiversity Action Plan 2016-2020 includes a habitat action plan for built structures, which encourages the incorporation in development of wildlife-friendly features such as green roofs. In 2017, it was estimated that there was 40,000m2 of green roof space located within the City of London.

Within densely built-up areas such as the City of London, it is important that buildings are environmentally sustainable. With the close proximity of the River Thames, the abatement of flood risk is also a significant issue.  Green roofs in the City of London minimise the urban heat island effect and flood risk, and provide rainwater run-off attenuation.

Whether intensive or extensive, biodiverse or brown, it is critical that green roofs are built on a solid waterproofing foundation.  Offering exceptional durability and outstanding green credentials, mastic asphalt is an ideal choice for specifiers seeking an eco-friendly waterproofing solution for green roof specifications.Recognised for its environmental performance and aesthetic properties, a green roof system laid with a mastic asphalt waterproofing system enhances the environment, controls storm water run-off and reduces noise and heat transmissions by upgrading the acoustic and thermal performance of a roof.

Robust Waterproofing Performance

When contractors use mastic asphalt for a green roof system, it eliminates the need for root barriers, which may well have been necessary had a substitute material been used. Alternative membranes to mastic asphalt can also be more prone to site damage leading to potentially catastrophic and expensive leaks. Mastic asphalt also offers a safe, flame-free application.

One of the most cost-effective, long term waterproofing membranes of its kind, mastic asphalt is being positively encouraged as an ideal solution to green roof and other waterproofing applications. Indeed, there are many examples where mastic asphalt has provided effective waterproofing for over 100 years.

In the unlikely event of a failure, mastic asphalt’s seamless structure means it can easily be spot repaired, eliminating the need for costly wholesale replacement. The flowing characteristics of the material also make it easy for installing contractors to tackle roof surfaces which are complex, stepped or with multiple protrusions. In comparison, failure is often found at the point of detail work in felt or sheet membrane waterproofing systems, where roofers have cut and fixed the material to the roof in question. A key objective of the Mastic Asphalt Council is to ensure that exceptional quality and workmanship standards are maintained for the installation of waterproofing installations utilising mastic asphalt.To maintain the industry’s reputation and ensure high-quality applications, trained craftsmen from MAC member companies install mastic asphalt under MAC’s strict rules.

Carbon Neutral

Mastic asphalt is carbon neutral and 10 years ago the mastic asphalt sector became the first industry in the world to achieve the CarbonZero standard. Mastic asphalt is 100% recyclable at the end of its useful life and it is able to be recycled and broken down into hardcore or used in roof screeds. Mastic asphalt can be specified on any green project, safe in the knowledge it will minimise the threat of climate change and be tough enough to take any green roof design.

With the future of roofing looking green, the reliability and integrity of mastic asphalt has seen more and more architects and designers specifying this waterproofing membrane for a wide range of green roof applications – from schools to hospitals, office buildings to apartment blocks – making it their preferred choice for biodiverse habits that will indeed benefit us all both now and in the future.

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