Learning lessons from Germany

Carl Bailey, Regional Technical Manager for Elevate UK & Ireland, explores how an EDPM single-ply roofing membrane has improved sustainability at a school in Berlin.  

Designed by German architectural practice MONO Architekten, the extension of the Free Waldorf School in Prenzlauer Berg, Berlin, marked a distinct departure from the site’s original architectural style. Tasked with extending a 1970s prefabricated building spanning five storeys, the architects opted for a more contemporary and visually dynamic appearance. 

Stretching towards the sports hall, the extension provides the school’s courtyard with a structural back to the street and a clear centre. The projections and recesses create different outdoor areas for various uses. A cluster of pentagonal structures in different sizes join together to form the unusual building with roof slopes designed in different directions.  

With sustainability at the core of the project, MONO Architekten specified natural and renewable materials wherever possible. The extension’s structures are timber framed and the outer walls filled with building straw and plastered with clay. Untreated larch wood planks of various widths serve as exterior cladding to evoke the feeling of a calm oasis in the middle of the busy European capital. Coloured clay plaster, wooden floors and wall heating integrated into the outer clay walls create a welcoming interior environment. 

No ordinary roof 

The entire roof area, including the pentagonal structures, are topped with green roofs to emulate the appearance of lush, mossy stones and provide more space for nature. A mix of low-growing herb grasses was selected, which during flowering season create a colourful display for the children while attracting pollinators to improve local biodiversity. 

The green roofs offer additional benefits, particularly in the urban setting. As well as having a positive impact on people’s health and wellbeing, the roofs help to mitigate the urban heat island effect by returning moisture to the environment while providing good thermal and sound insulation. 

Sustainable waterproofing 

In line with the architect’s creative vision, the roofing membrane for the new extension had to be sustainable, efficient, versatile and flexible, offering a perfect fit for the irregular shapes of the building. It also had to be lightweight and robust enough to provide a durable foundation for the green roof system. 

To meet these needs, Elevate’s RubberGard EPDM single-ply roofing membrane was specified. Made of synthetic rubber, EPDM membranes are designed for waterproofing flat and low slope roofs. Its sustainable features are widely recognised by international institutions such as Greenpeace, and the Dutch Institute for Building Biology and Ecology (NIBE) have named it as the roofing membrane with the least environmental impact, offering a durable, long-term solution for modern architecture.  

In its latest evaluation, NIBE states that EPDM roofing membranes are the most environmentally friendly choice for flat roofs. Carried out every two years, the analysis compares the initial costs (material and installation costs) as well as all hidden environmental costs (raw material consumption, energy consumption during production) of roofing membranes from different manufacturers. No harmful substances are released during or after the installation of an EPDM roofing membrane, making it safe for rainwater harvesting. Thanks to an improved formulation, the release of carbon during operational use has also been almost eliminated.  

The longevity of EPDM single-ply roofing membranes has also increased. The absence of plasticisers allows the membrane to retain its flexibility without the risk of migration, which can lead to cracking, flaking and ultimately the failure of the roof surface. The membrane will return to its original shape and maintain its performance after any expansions or retractions caused by severe weather, ensuring it can adapt to the roofs’ irregular shapes.  

EPDM roof membranes evaluated in Central European climatic region have been independently studied with the conclusion that a service life beyond 50 years may be expected. 

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