EPDM (ethylene propylene diene monomer) is a synthetic rubber membrane used on flat and low-slope roofs. It is known for its flexibility, which helps it accommodate normal building movement and temperature changes. EPDM is commonly sold in large sheets, allowing installers to cover broad roof areas with fewer seams.

The membrane is available in different thicknesses and is most commonly black, though white options also exist. Black EPDM absorbs more sunlight, while a white surface reflects more of it. The right choice depends on the building and its climate. EPDM can be installed using adhesive, mechanical fasteners, or ballast, depending on the roof design and the specific product.