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What Is Modified Bitumen Roofing?

As a Texas business owner, you work hard. You think carefully about how to take care of your business, and you take pride in its success. 

Along the way, you’ve been forced to learn about a lot of things outside of your original expertise. You had to learn enough IT to keep the business running. You also have to learn about real estate, property, insurance, and more. 

To top that list, you’re also responsible for your building’s roof. 

It’s a lot to know, but thankfully, you have resources like Redline Roofing to help fill in any knowledge gaps. 

With that in mind, we want to take a minute to teach you about modified bitumen roofing.

What Is Modified Bitumen?

Modified bitumen is a common choice for industrial roofing. It is a multilayer roofing option that is destined for roofs with low slopes. It doesn’t belong on pitched roofs. Instead, it is ideal for a flat roof with a mild slope that manages water runoff.

The key to modified bitumen is in the layers. The layers include asphalt, polymerized rubber (or thermoplastic), and a fiberglass reinforcement. All of these layers go above an insulation layer, making this a robust roofing option.

Modified bitumen is very strong, making it great for roofs that hold storage or see heavy foot traffic.

How Is It Installed?

Most of the layers in modified bitumen are premanufactured into rolls. Once the insulation layer is established, the first layer of modified bitumen is rolled across the roofing substrate. It is fastened using industrial adhesives.

Older versions of modified bitumen would use welding or other heat applications, but these days, adhesives are considered safer and more reliable.

Each layer is attached to the previous layer, and finally, the asphalt is put down as a final topping layer. Asphalt alternatives are available for roofing that aims to maximize thermal efficiency or other specific aspects of the roof.

When Is It Best Used? 

As stated before, modified bitumen is ideal for large, flat, industrial rooftops. The best options will be unwalled roofs that allow for easy water draining. While modified bitumen can handle some ponding, it is designed primarily for roofs where ponding is not a common occurrence. 

When it comes to rooftops in use, modified bitumen is often the very best roofing option. It is extremely durable, making it ideal for rooftop storage, and the asphalt layer makes for safe footing. That is why it is preferred for rooftops with frequent foot traffic

What Are the Pros and Cons of Modified Bitumen?

There are many aspects to modified bitumen. The multilayer design comes with a number of pros and cons. Below, you’ll see the most prevalent of both to better help you decide whether this might be the right roofing choice for your building.

Of course, you can always consult an expert to get a full conversation and deeply understand your roofing options. Until then, here’s the quick list to help you see what modified bitumen has to offer.


In most cases, the pros outweigh the cons for modified bitumen, which is why it is such a popular roofing choice.

First, it is extremely durable. The multiple layers are difficult to puncture and crack, and each layer provides redundant durability to the whole roof.

By that same token, modified bitumen is very waterproof. As long as ponding isn’t an issue, these roofs very rarely leak, as each layer provides a watertight seal.

As mentioned before, modified bitumen is ideal for rooftop storage and foot traffic, being one of the safest roofing options in both cases.

It is also flexible, which makes it unlikely to fracture even in the face of extreme temperature ranges.

On top of all of that, modified bitumen is also energy efficient. The multiple layers make for good insulation, and depending on the type of modified bitumen chosen, it is possible to have high solar reflectivity, reducing heat costs during the warm months.


As good as modified bitumen can be, it’s not ideal for all roofs. Because it has multiple layers, it is a heavy roofing option, and that can disqualify it as an option for many roof designs.

It also struggles with ponding. Infrequent ponding is not a problem for modified bitumen, but rooftops without clear water drainage are better served by other materials. Frequent ponding can prematurely wear modified bitumen, leading to a number of roofing issues.

Modified bitumen is not highly flammable, but there are roofing options that are even more flame resistant. 

Lastly, modified bitumen installation is more involved as compared to single-ply roofs. This can raise the installation costs for a new roof.

Redline Roofing Is Here to Help

If a modified bitumen roof sounds like it might be right for your building, contact Redline Roofing today. We’ll discuss all of your options so that you know what is available and how to get a great deal on the perfect roof for your building.