Modified Bitumen vs. EPDM: Which to Choose?

Modified Bitumen vs. EPDM: Which to Choose?

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If you are in the process of constructing a new commercial building, house, or anything in between, one of the most important components is the roof. That said, there are a few different options to choose from as far as roofing systems are concerned.

Two of the most popular types of roofs used nowadays include modified bitumen and EPDM. Today, we want to take a closer look at these two types of roofs, compare them with each other, and figure out which one is best for you.

What Is Modified Bitumen?

First, we have modified bitumen roof, which is often considered to be one of the most durable roofing systems in the world, which is why it has been in use for over 100 years.

This type of roofing involves using many layers of roofing materials together. Here, you will see many layers of asphalt, plastic, fiberglass, and polymerized rubber, which serves to create a very rugged yet flexible waterproof membrane that is resistant to many forms of damage, particularly impact.

Furthermore, modified bitumen itself consists of plastic, rubber, and asphalt. Here, you will see large rolls of materials that are placed between various layers of felt, which are then coated with scorching hot modified bitumen, which are then known as caps sheets or polymer layers.

Depending on the exact materials used, which can differ from one specific application to another, the modified bitumen roofing membranes may be installed as a part of a two-layer system or a multi-ply system.

A modified bitumen roof can technically be used for any kind of roof, although it is usually used for flat and semi-flat roofs, most often for commercial purposes. One of the biggest advantages of modified bitumen roofing is that it is very long-lasting, strong, and durable.

However, a big downside here is that it is very hard to install, as it takes a long time and is extremely dangerous due to the materials and processes involved. Therefore, modified bitumen roofing is not something that regular homeowners can do on their own without proper training. That said, although it can be difficult to install, it should last for around 30 years at the least.

What Is EPDM Roofing?

Then there is EPDM, otherwise known as propylene diene monomer roofing. This is one of the newest types of roofs around, and it’s often used for flat roofing. This method can be extremely durable and practical, as well as quite cost-effective.

It has a lot of advantages practically, although it’s certainly not very good-looking. Most people would agree that this is by far one of the least visually appealing types of roofs you could have. Some would say that it’s downright ugly.

However, other than the fact that it doesn’t look very nice, it is one of the best options around, particularly because it might last for longer than 30 years, as it is very resistant to various forms of damage, and very durable overall.

It is very resistant to tearing, impacts, wind, hail, temperatures, UV radiation, thermal shock, and more, so it’s a great option to go with if you live in an area that sees a lot of extreme weather. It also happens to be extremely lightweight and not too difficult to install.

As long as you don’t have to look at this type of roof too much, it’s ideal to use for low-slope roofs and flat roofs alike. This system also doesn’t require all that much maintenance, and when maintenance is required, it’s usually pretty straightforward.

EPDM Roofing vs. Modified Bitumen: What Are the Differences

Now that we know what both EPDM roofing and modified bitumen roofs are, let’s take a closer look at the main differences between them.

Overall Durability

One aspect worth noting here is that while both of these types of roofing materials are very durable, modified bitumen roofs are more durable than EPDM. In essence, EPDM roofs really just consist of a thick layer of rubber.

This thick layer of rubber is quite resistant to various elements, especially UV rays, wind, and moisture, and it is physically durable, although it is somewhat easy to puncture. We then have modified bitumen roofing, which consists of several layers of extremely durable materials.

In the grand scheme of things, modified bitumen is more weather-resistant, impact-resistant, and tear-resistant than EPDM. If you need a type of roof that is going to last longer than the other, bitumen is the choice. Although both may last for 30 years or longer, you’re much more likely to get to that point with modified bitumen.

Chemical Resistance

Something else to consider here is that EPDM roofs are not very resistant to chemicals, as petroleum, oil, and grease can all cause major damage to this type of roof.

On the other hand, the modified bitumen roof is actually very well known for being quite resilient on this front. A wide variety of chemicals, even corrosive substances, should not have much of an effect on a modified bitumen roof.

Heating and Cooling Costs

One big advantage that EPDM roofing has over modified bitumen has to do with heating and cooling costs. The reason for this is that modified bitumen roofs are usually always black.

While this can be good for some things, it’s not ideal for cooling in the summer. We then have EPDM roofing, which is available in many colors, including both black and white.

This means that if you live in a hot climate, the white option is better, whereas the black option is better for cooler climates. This kind of diversity is essential when it comes to maintaining low heating and cooling costs.

Installation and Maintenance

In terms of overall installation and maintenance requirements, EPDM roofing is much simpler. Although it’s not something we recommend installing on your own, technically speaking, it might be possible.

This is because it has limited installation and maintenance requirements compared to modified bitumen. Modified bitumen is very hard to install and often even harder to maintain.


Something else to consider here is that an EPDM roof will usually cost you an average of $10 per square foot, or even less, whereas a modified bitumen roof usually won’t cost more than $4.00 or $5 for each square foot.


There is just no denying the fact that a modified bitumen roof looks much nicer than an EPDM roof.

EPDM Roofing vs. Modified Bitumen: Which One Should You Choose?

What it really comes down to here is durability versus ease of installation and maintenance.

Modified bitumen is by far the more durable and longer-lasting of the two, but it’s also much harder to install and requires more regular maintenance, with this maintenance also being more difficult.

While modified bitumen is about half the price to install, it also doesn’t perform as well in terms of heating or cooling costs.


We hope that our guide on modified bitumen and EPDM roofing has been informative for you, so you can now make your own decision on the matter.