The challenges of green and blue roof waterproofing

There are many different types of membrane – and all can be used to waterproof a green or blue roof. Traditionalists, however, might argue that hot mastic asphalt, which has long been considered a waterproofing solution for green and blue roofs for many decades, should be the first choice. 

However, the traditional application process, which involves heating and melting the material, presents several challenges and this in turn is encouraging the use of cold applied solutions which offer the same seamless benefits of mastic asphalt, but without the risks. Hot work, for example, poses safety problems for workers and can create potential fire hazards. The heating process can also contribute to air pollution and increased energy consumption and hot asphalt application can be disruptive to building operations, especially for existing buildings.
It is against such a background that a membrane such as Proteus Cold Melt® is being increasingly used for green and blue roof applications. It offers a compelling alternative by combining an expected performance life of the structure once covered, with the safe use of a cold applied membrane. Avoiding the risk of fire. Cold Melt®, as the name suggests, is applied cold, eliminating the need for hot work and associated safety risks.

The comparisons with mastic asphalt are numerous. The seamless application, in particular, means there is nowhere for plant roots to go at any time in the future – a potential problem for some membranes – and like mastic asphalt, Cold Melt® is BBA certified to last for the lifetime of the substrate on which it is installed.
It is a membrane that provides an expected performance life of the structure. Its flexibility allows it to accommodate structural movement and withstand the weight of soil and plants. Its formula includes re-cycled rubber crumb and other organic materials

Cold Melt® is not just a waterproofing membrane - it is a system that can be integrated into various roofing and waterproofing applications. It can be used as part of inverted roof insulation systems, green roofs and podiums. The system can provide a waterproof finish for the design life of the roof.   
The UK has seen a increase in the installation of green and blue roofs in recent years, driven by a combination of environmental concerns, government incentives and a growing awareness of their benefits. Industry estimates suggest that London currently leads the way in green roof installations, accounting for approximately 42% of all UK green roofs.

While data on blue roof installations is less extensive, there is a clear trend towards their adoption, particularly in areas prone to flooding. Blue roofs are often combined with Sustainable Drainage Systems (SuDS) to provide flood management solutions, which is why there are more and more Government initiatives and regulations to encourage the installation of blue roofs to address water management challenges.

Most importantly, there is a growing understanding of the benefits of green and blue roofs, leading to increased demand from both public and private sectors. Innovations in green roof technology, such as lightweight substrates and self-watering systems, are also making them more accessible and often bring the cost of them down.

While specific statistics on the total number of green and blue roofs installed in the UK may be limited, the available data indicates a clear upward trend. The increasing popularity of these roofing solutions reflects a growing commitment to environmental protection and sustainable urban development.