Flat RoofsEPDM (ethylene propylene diene terpolymer) is an extremely durable synthetic rubber roofing membrane.20 year guarantee.50+ years life expectancy.It is highly flexible and will move with any movement of the building.It can be walked upon.It is enviromentally friendly.It can be installed all year round.It is attractive, a colour choice of black or white UPVC trims are used, which is often the only part visible.It's not expensive.