Modified bitumen roofing is one of the world’s most widely used flat roof systems. Modified bitumen roofing systems have provided commercial building owners a reliable option for high-traffic roofs for decades. But there are other benefits of modern modified bitumen membranes.

What is a Modified Bitumen Roofing System?

A modified bitumen roof is similar to a built up roofing system as both utilize asphalt. However, in a mod bit roof, the asphalt is modified with polymerized rubber or plastic, then reinforced with fiberglass to make the waterproof membrane more flexible.

Types of Modified Bitumen Roof Systems

Two main types of modified bitumen roofing exist: SBS modified bitumen roofing and APP modified bitumen roofing.

  • Styrene Butadiene Styrene (SBS) is installed using cold adhesive or hot moppings of asphalt. This type of system has a rubber-like appearance.
  • Atactic Polypropylene (APP) is either heat-welded or torch-applied. The back of the sheets is coated with modified asphalt that melts when heated with a propane torch. The adhesive holds the system together. An APP system has a plastic-like quality.

Benefits of Modified Bitumen Roofing Systems

Mod bit systems have had longevity in the commercial roofing industry for several reasons.

Modified bitumen roofing is a multi ply system that offers greater thickness and redundancy to protect your commercial building. One benefit of this multi-layer system is that it can withstand foot traffic better than other roofing materials.

A multi-layer modified bitumen also has an insulating layer that helps with extreme temperatures and reduces energy consumption.

Modified Bitumen holds up well under UV exposure and hot and cold temperatures.

Mod bit roofing can last up to 20 years – as long as it was professionally installed and maintained – since the additive increases the flexibility of the asphalt.

One disadvantage of mod bit flat roofs has changed over the years. It used to be that black was the only color option for modified bitumen low slope roofs. Of course, dark colors absorb the heat from the sun and cause energy costs to rise. However, now you can choose lighter color options for your modified bitumen roof. You can also select highly reflective cap sheets to make your roof membrane more cool roof compliant.

Finally, a modified bitumen roof works well with “roofing cement,” often used to patch an emergency leak – since these products are made for asphalt-based systems.

Drawbacks of Mod Bit Roofs

Even though this roof system is known for its membrane thickness, energy efficiency, and higher-than-average life expectancy, mod bit roofs have a few drawbacks.

One drawback is that there are some risks with propane torch, high heat application roof installation techniques required for APP roof systems. Therefore, the commercial roof company you select for the job should use highly trained roofers familiar with the installation process.

Another drawback to a modified bitumen roofing system is that standing water can damage the roof surface. You must have a sound drainage system if you have a mod bit system.

Contact AAA Roofing for More Information on Modified Bitumen Roofing Systems

AAA Roofing is a leading commercial and industrial roofing contractor serving the Western states. We specialize in new construction, re-roofs, tenant improvements, roof maintenance, and leak detection. Learn more about our cost and availability to install modified bitumen systems by contacting a member of our team today.

Key Takeaways

  • Modified bitumen is considered a cousin of built of built up roofing systems. Synthetic rubber is added to the asphalt bitumen – making it more flexible.
  • There are two main types – cold process adhesive and heat welded or torch applied.
  • Modified bitumen is a popular roofing material because it can hold up to foot traffic, is long lasting, and is a thick, redundant system.
  • Pooling water breaks down modified bitumen roofs, so you must take drainage seriously.