EPDM roofing is a kind of roofing material primarily used to finish roofs with little to no pitch. But can it be used on pitched roofs? Here’s what you should know.

Understanding Roof Pitch

Roof pitch refers to the slope created by the underlying roof rafter. It is often represented as a ratio between the rise and the run using x by 12 (x:12). To learn more about this, read our blog on how to calculate roof pitch.

You can generally categorize roofs into the following categories:

Flat roofs: These roofs are actually not perfectly flat, since they require a gentle slope to prevent water from pooling. Generally, these roofs will have a pitch in the range of 1/2:12 to 2:12.

Low pitched roofs: These roofs have pitches that fall below 4:12. Since they require special materials to prevent leaks, they can be difficult to maintain.

Conventional roofs: Most roofs will have a pitch in the range of 4:12 to 9:12. They are the easiest kinds of roofs to construct and are much safer to walk on.

High-pitched roofs: These roofs often demand additional fasteners and have steep pitches that can reach 21:12.

Roof pitches that have lower angles (1/12 to 3/12) are generally found in industrial buildings and in more urban, contemporary housing. It was fashionable for contemporary-style homes built in the 1960s to have less pitch. In many instances, there was just a negligible slope to help water drain. Visually, these roofs appear flat. The flat roofing materials considered most appropriate to these shallow-sloped roofs include EPDM. As roof pitch increases, EPDM becomes less practical. That said, it can still be used on some pitched roofs with some limitations.

epdm roofing roll

Understanding EPDM

EPDM is a great roofing option for many homes and businesses. EPDM roofs can remain functional for up to four decades or longer. With its long lifespans, this roofing material is a terrific investment, as long as your structure fits the requirements.

If you’ve looked into EPDM roofing and decided you are interested in this kind of roofing material, you will first need to determine whether your business or home is a candidate for the product. Due to its unique traits, EPDM roofing is most appropriate for roofs with very little slope. Structures with steeply pitched roofs won’t be good candidates for EPDM roofing unless the building is re-engineered to have a flatter roof.

The availability of a wide range of components and accessories makes EPDM roof systems versatile. For instance, the membrane directly adheres to wood and structural concrete decks. It can also be anchored mechanically to steel decks. For decks that have low pullout resistance (light gauge steel, fibrous cement and gypsum), there are special fastening components. A qualified roofer can use ballasted assemblies on any deck as long as the building is capable of holding the weight of the installed roofing system. The choice between a mechanically fastened, adhered, or a ballasted assembly will often be influenced by the kind of structure and its existing condition. With all that said, as versatile as it is, EPDM comes with certain limitations that make it a poor choice for roofs that have more than a slight pitch.

But how much pitch is too much? The answer will depend on your individual structure and the person you’re asking. Some roofing contractors are happy to say yes to any project without telling the customer about potential consequences. If you want a straight, honest answer, you need to ask a reputable roofer.

In rare instances, EPDM membranes can be used on roofs with higher pitches, but there are big limitations. In many regions, local building codes forbid this kind of work. What’s more, even if you are allowed to apply EPDM to a sloped roof, the results may not be warrantable. If you aren’t sure whether your roof is a good candidate for EPDM, it’s best to get an assessment from a qualified, reputable local roofing contractor. If you have a pitched roof, however, there is a better roofing product available in almost every instance.

Need a new roof for your home or business? A to Z is ready to help. Hoping for budget-friendly repairs for weather- or age-related damage? We can do that too. At A to Z, we’ve spent decades earning a widespread reputation as one of the state’s leading roofing contractors by providing skilled workmanship and honest customer service. Contact us to learn more and to get a free estimate on your next roofing project.