top of page


Modified bitumen, or MB, roofing systems are asphalt-based roofing systems that are similar to the built-up, or BUR, roofing systems. This type of roofing structure is specifically designed for low slopes or flat roofs. The engineered modified bitumen roofing systems with five layers of protection are designed to withstand the harsh outside elements. 

About the 5-Layer System

The framework for a modified bitumen roofing system consisted of five layers. The first layer is insulation for providing temperature stability. Next, modified base sheets are applied. Then, the modified bitumen membranes that are made up of co-polymer and reinforced with polyester or fiberglass are laid. Following that, adhesive is applied with either a hot or cold agent for waterproofing. The final layer is surfacing, which helps protect the roofing system from UV rays and weather. 


Types of MB Sheets

There are two main types of modified bitumen sheets that can be laid, APP or SBS. APP, which is short for Atactic Polypropylene, is a thermoplastic placed in the asphalt to reflect UV rays in colder temperatures. SBS, or Styrene-Butadiene-Styrene, is more like the BUR roofing systems and is a rubber polymer mixed with asphalt. A commercial roofing contractor with extensive roofing knowledge can help determine what type of materials are right for each specific roofing project. 


Benefits of Choosing a Modified Bitumen Roof

This type of roofing structure is still used today because of its many benefits for commercial buildings. Because it has been in the market for so long, it has a proven track record for durability and longevity. MB also has track ratings for being a waterproof material. It is also known for its high tensile strength. The flexibility of this type of roofing also makes it a popular choice. There are many types of application methods to choose from as well as a variety of surfacing options such as “cool roofing .”Other options for modified bitumen roofing systems include flame-free or VOC installation. Another added benefit of MB roofing is its cost efficiency and life span, with many long-term warranties available. There are many quality benefits of this type of roofing structure that still make it a popular choice on the market today for commercial structures. 


For more information about modified bitumen roofing systems or to receive a free estimate for roof replacement or repair costs, contact Certified Commercial Roofing. We are here for all your commercial roofing needs. 

Need Help With Your Roof?


Thanks! Message sent.

bottom of page