What is EPDM Rubber?


EPDM rubber is a type of synthetic rubber. It is extremely durable and flexible and therefore has a wide range of applications, including in vehicles (where it is used for window and door seals, as well as cooling system hoses), cold-rooms, non-slip coatings for decks and playgrounds and many others besides. In simple terms, pure rubber becomes brittle with temperature variable, wherein synthetic rubber (EPDM) remain flexible and withstand temperature variations for decades.

The use of EPDM in roofing is what we will be exploring in this feature. This particular material lends itself incredibly well to roofing systems due to its unique combination of material properties. We will expand on this in this article and also in our Why Use EPDM? guide (coming soon).

EPDM is a copolymer with elastomeric properties, which means it is a polymer which is both viscous and elastic. If stretched, it will return to its original shape. Its two main components (ethylene and propylene) are both derived from oil and natural gas.

What Does EPDM Stand For?

EPDM stands for ethylene propylene diene monomer, which is a bit of a mouthful, so it’s commonly shortened to EPDM or EPDM rubber.

EPDM gets its name from the chemicals (monomers) that are mixed together in various proportions to form it. These are ethylene, propylene and diene. The ethylene content is usually between 45% to 75%.

The diene monomers, while only form a small part of the composition of EPDM, provide the cross-linking that gives incredible resilience, flexibility and durability. The excellent material properties of EPDM come from this molecular mesh structure and make it unbeatable in terms of elasticity and resistance to ageing.

What is EPDM Roofing?

EPDM roofing is a catch-all term for a variety of different roofing systems. These systems consist of a single layer rubber membrane, used in conjunction with other components, such as vapour barriers and thermal insulation, as well as accessories (drainage, pipes, gravel guards etc), and, in the case of green roofs, vegetation.

EPDM can be used in a variety of different ways, as we’ll see shortly, but it’s really come into its own in the flat and low-pitched roofing sector due to its strength and resistance to weathering, as well as the fact that EPDM sheeting allows for a consistent application and thickness across the entire roof area.

While, like many other elastomers, EPDM is tear-resistant, with a high tensile strength, what sets EPDM apart from in terms of its suitability for roofing is its ability to withstand everything the environment can throw at it, from extreme heat and cold to ozone and UV rays. This makes it unmatched in terms of weather-resistance, which is why it is so ideally suited for roofing.

EPDM roofing

EPDM Roofing’s History

CARLISLE® CM Europe and EPDM go back a long way. Today, we are Europe’s leading manufacturer of EPDM sheeting, but in years gone by, our various companies throughout Europe started out as rubber works.

The CARLISLE brand started in 1917, in Carlisle Pennsylvania, as a manufacturer of bicycle and car tyre inner tubes, but in fact its foundations were laid in 1856 when brothers Albert and Louis Cohen founded a factory making rubber shoes. Over the years, it’s grown and grown, to become the multi-national company it is today, with offices and manufacturing facilities all over the world.

Nowadays, we’re Europe’s leading manufacturer of EPDM roofing membranes.

EPDM Wins a Nobel Prize

A German scientist called Karl Ziegler is responsible for the scientific breakthrough that led to the EPDM production process, while working on polymerisation. He realised that there were traces of nickel in the autoclave used for the reactions, which caused the reaction to stop. By using a titanium and aluminium-based catalyst instead, and carrying out the reaction under atmospheric conditions, Ziegler and his students discovered that not only could the reaction be accelerated, but it produced a polymer that was strong, flexible and had a high tolerance for heat and cold. In addition, this could be done at normal pressure.

Before this discovery, ethylene had been considered difficult to polymerise, with high pressures and high temperatures needed. The polyethylene that came from Ziegler’s discovery was therefore not only easier to produce, but also was more rigid and had a better resistance to high temperatures than its high-pressure counterpart. Within 3 years of the discovery, 200 metric tons of the new plastic had been produced.

Ziegler disclosed his catalyst to the Montecatini Company, where an Italian scientist called Giulio Natta was acting as a consultant. Natta expanded on Ziegler’s work, and the Ziegler-Natta catalyst was born. In 1963, Karl Ziegler and Giulio Natta were awarded the Nobel Prize for Chemistry for their work on controlled polymerisation, which greatly enhanced the progress of plastics and their applications.

nobel prize medal

How Can EPDM Be Used?

While rubber had been used in various applications for centuries, during the 20th century, synthetic versions began to come to the fore. Natural rubber can degrade and crack under extreme conditions, however the synthetic alternatives could be engineered to possess different qualities, and therefore tailored to various different purposes.

EPDM was first introduced in the USA in 1962 and since then it has been adopted by many different industries for many different applications, from HVAC to hydraulic brake systems and from electrical insulation to eco-roofs. This is thanks to its ability to withstand so many different weather conditions and thermal and mechanical influences.

Although this article has mainly focused on EPDM roofing, in actual fact, our EPDM products can also be used in many different ways when it comes to construction or renovation projects.

EPDM reference arnheim

Pond Liners

Water is just the thing for creating a relaxing, natural-feeling ambience in outdoor spaces, whether it’s a pond, a water feature or a stream. And with EPDM pond liners, it’s incredibly easy to do! Not only can the pre-assembled pond liners be installed quickly and easily, but they’ll last more than 30 years. In addition, EPDM is leach resistant and contains no toxic substances, so it’s perfect for fish, plants, birds and associated wildlife.

Green Roofs

Looking to make use of your roof space in an eco-friendly manner? Not only does a green roof look great, but it also helps to save energy, reduces noise pollution, provides a habitat for wildlife and improves water quality. Our EPDM membranes are ideal as waterproofing bases for green roofs, as they are factory-fabricated, root-resistant and long-lasting.

Waterproofing for Facades, Terraces and Balconies

EPDM, when used as a waterproofing material for facades, provides interesting opportunities for architects to blur the normal boundaries of building envelope design. Providing soft edges, smooth surfaces and a seamless transition between roof and walls, EPDM is the ideal solution for all your waterproofing needs.

Solar Roofs

A key consideration when installing solar roofs is that the roofing material used should have a longer service life than the solar panels. EPDM has a service life of over 50 years, making it an ideal candidate for this.

Water Tank Liners

As the molecules of EPDM are so tightly packed, it is very difficult for water and vapour to pass through it. This makes it ideal for use in lining water and biogas tanks. As does the fact that, even over time, it does not shrink or crack.


Here we have explored about what EPDM is and its various applications, in particular, its use in roofing and waterproofing. As you can see, it’s a product with a fascinating history and many, many uses, and we are pleased to be Europe’s largest manufacturer.

For more information, contact us to find out how our EPDM roofing and waterproofing systems can be used in your construction project.

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