What is Modified Bitumen Roof + Pros & Cons

Flat roofs have been around for a very long time, and they’ve held the spotlight for being the go-to option for commercial roofs. They were always a popular preference for commercial buildings, and now they are also gaining momentum for residential ones. One of the most preferred roofing choice for flat roofs has been Modified Bitumen.Ā 

What is Modified Bitumen?

Modified Bitumen was developed in Europe during the 1960s, and it is a rendition of the old built-up roofing (BUR) system. Modified Bitumen flat roofing is a single-ply system made of asphalt bitumen, modified with polymers, and reinforced with fiberglass and/or polyester.Ā 

It is assembled in a unique permutation of layers that compound to increase the roof’s effectiveness. Itā€™s this permutation of materials that gives Modified Bitumen competitive advantages that few other roofing systems can match.


Modified Bitumen ProsĀ 

  1. Seamless Connections

There are three popular ways to install Modified Bitumen: self-adhesive, cold adhesive, and heat. All of them create a tight connection creating a consistent and seamless connection between the sheets.Ā 

  1. Leak Resistance

One of the top concerns associated with flat roofing systems is leakage. However, due to the coherent nature of this roof’s installation, leakage is not a problem.

  1. UV and Heat Resistance

Modified Bitumen is well known to be heat reflective. These reflective properties also make it resistant to the sunā€™s radiation. This can help to reduce energy costs, especially if lighter colors or more reflective top coatings are used.

  1. Tear ResistanceĀ 

Due to the combination of fiberglass and/or polyester reinforcement layers, these roofs are tear-resistant and can handle foot traffic well.

Mod bit

  1. Weather ResistanceĀ 

Modified Bitumen Roofing Systems are designed with a 5 layer composition to withstand harsh exposure to all seasons and other dangerous environmental elements.

  1. Style Options

You have multiple options for color with this roofing. The granules on the cap sheets can vary to match any color of shingles.Ā 

  1. Easy To Install & repair

Modified Bitumen is easy to install. They come in rolled sheets that are 3 feet wide and up to 36 feet long, which are rolled easily onto the roof atop a base sheet membrane. If damaged, bitumen patches can be used to quickly and efficiently repair it.Ā 

  1. Environment Friendly

Some Modified Bitumen materials can be recycled. This means that your roofing materials can get reused and it can avoid getting added to the inevitable dump pile. This will help reduce your carbon footprint.Ā 

Flatroofing 2

Modified Bitumen ConsĀ 

1. Lifespan

Modified Bitumen has a life expectancy of 10-20 years. Although not extremely low, it is still one of the lowest out of all the roofing materials options available.Ā 

  1. Water Resistance

In the absence of a proper drainage system set up on a flat roof, water is bound to get collected on the surface. When this occurs, Modified Bitumen is known to wear down faster in comparison to other flat roof types like TPO or PVC.Ā 

3. Torch Fumes

One of the famous and reliable methods for Modified Bitumen installation is by using a blow torch to extreme heat and install the sheets. This can release harmful fumes which can be dangerous if contact is not avoided.Ā 

4. Foul Odor

You will likely notice a strong odor after the installation process is done. The spread, intensity, and lasting effect of the odor depend on the area covered in installation. Consider getting your roof installed when you are prepared to either relocate temporarily or deal with the smell for a few days.


The pros which make them a customer choice are its low maintenance, reliability, and nature-friendly properties. While the cons people consider is the installation technique and lifespan. But despite competing flat roofing solutions like TPO and PVC, Modified Bitumen roofing has continuously held its ground by leveraging its superior advantages over disadvantages and been a reliable choice of roofing.

Related Articles

11 Best Gutter Guards for a Low Maintenance Home

What is a Mansard Roof and What Advantages/ Disadvantages It Carries

Types of Rolled Roofing for Easy & Cost-Effective Roofing

Leave a Comment