Modified Bitumen Roofs

Modified Bitumen Systems are installed over low sloped (flat) roofs. Modified Bitumen is asphalt that has had modifiers added to it to give it plastic or rubber-like properties. The roofing sheets of a Modified Bitumen System consist of a reinforcing fabrics (usually polyester or fiberglass) and modified bitumen. The roof systems usually consist of two or three layers of modified bitumen sheets.

There are two types of Modified Bitumen Systems:
  • SBS (styrene, butadiene, styrene)
    SBS Systems are usually installed by means of hot asphalt or a cold adhesive. Systems applied with cold adhesive can be advantageous when asphalt odor is a concern.
  • APP (atactic polypropylene)
    Modified Bitumen Systems are usually installed by means of a torch applied flame. Because there can be a fire hazard with this type of system, it needs to be installed with caution.
If installed properly, Modified Bitumen Systems can be of extremely high quality. A good fit for Modified Bitumen Systems are buildings where leakage cannot be tolerated. Examples of this would be over electronic switching equipment for phone companies or critical equipment used by electric companies.