Friday, November 4, 2011

Limitations of Modified-Bitumen Roof Membranes

Modified-bitumen options are even more complex than built-up roofing options. Not only are there two major types of modified-bitumens — those based on rubber modifiers (SBS and SEBS) and those based on plastic modifiers (APP) — but there are different installation methods that can be used with the different membranes.

Generally speaking, SBS membranes are applied with hot asphalt or cold adhesives, though they can be torch-applied. APP modifieds are generally torch-applied, but some can be adhesively applied. Almost all modified-bitumen membranes are surfaced with granules, making them less heavy than the traditional gravel-surfaced, built-up roof. Often, a modified-bitumen membrane will be used as a cap sheet on a traditional built-up roof. This gives the redundancy of a built-up roof with the flexibility of a modified membrane.

Modified-bitumens share most of the pros and cons of built-up roofing with one major difference - the modified bitumens were developed to perform better in cold weather by remaining flexible at low temperatures. They can stretch and relax with temperature changes better than built-up systems.

APP and torch-applied SBS systems should be used with care if there are flammable items on the roof, such as wood parapets. The membranes can smolder and erupt into flames long after being torched. They are the best choice of the modified-bitumen membranes if odor is a problem because there is no adhesive to flash off or asphalt to cause smells during installation. APPs and cold-adhesive-applied modifieds are equally good choices if delivery to the roof is limited, as both can be delivered via freight elevator and stairs.

Look for a Conklin Roofing Systems contractor in your area:

Patton Services | (309) 303-3128 | |


  1. As a good Post. All the surface of the particles of modified bitumen membranes, so that they weight less than the traditional gravel surfaced to build the roof. Typically, modified bitumen membrane will be used as a traditional built-in roof on the first table.

    torch on roofing

  2. Thanks for the information on roofing. I really don't understand everything put this blog has been so useful!

    torch on roofing vancouver

  3. Thanks Shanna!
    Glad you enjoy the info!

  4. I think that it would be kinda fun to do a torch on roofing project. Thanks for sharing, I think I may just have to go up to Vancouver and gather up a few friends to help me with something like this.

  5. I wasn't really sure what torch on roofing was. Your post was really informational. I am a little worried about torch on roofing in Vancouver still though. I will be sure to look more into it. Thanks for the thoughts!

  6. I have a friend that said something about torch on roofing in Vancouver. What is that? I have never heard of it before.