After careful consideration, the architects specified the use of an EPDM roofing system. EPDM membranes are 100% cured, single-ply roofing membranes made of a synthetic rubber Ethylene-Propylene-Diene Terpolymer. Thanks to their stable chemical composition, they offer high resistance to UV radiation, ozone, alkaline rains and extreme temperature fluctuations. Robust yet flexible, EPDM roofing membranes adapt to the structural movement of buildings during their entire lifetime. With a life expectancy of more than 50 years, they are also the most sustainable roofing membrane in the market, as stated – among others – by the Dutch Institute for Building Biology and Ecology (NIBE).
In addition to its longevity and outstanding waterproofing qualities, EPDM is a chemically inert material which does not contain any plasticizers or flame retardants and therefore does not release toxic substances into the environment. This makes EPDM roofing membranes particularly well suited for the collection and use of run-off rainwater, as is the case at the Batsford Arboretum’s visitors’ centre.
The EPDM roofing membrane used in this project was Firestone’s RubberGard EPDM, with a thickness of 1.1 mm. The membrane was fully adhered to the irregular, wavy shape of the plywood roof deck using contact adhesive. To harvest the rainwater, the roof outlets were set into large sumps in the low points of the curves. Water is then collected in irrigation tanks below the main building and used to water the plants in the garden centre.
How is the system functioning after almost a decade in use? “Nine years on, the EPDM roofing system is still performing very well and we are pleased with it”, says Stuart Priest, Director of Operations at the Batsford Arboretum. “Other than sweeping down the gullies and cleaning out the drain points a couple of times a year there has been no need for bigger maintenance works.”