Modified Bitumen SBS Membranes

Modified Bitumen is a common flat roofing system that consists of asphalt with added modifiers to give it a rubber-like quality. Mod-bit membrane rolls come in 36”-39” widths and cover an area of approximately 100 square feet. Surfacing can include mineral granules, copper, aluminum, or aggregate. Mod-bit systems are usually one, two, or three-ply systems and are typically torch-applied. Installation costs are less than most single-ply systems on the market today. Mod-bit is available in a variety of colors, whereas EPDM is typically limited to black or white.

Since most Mod-bit systems are torch-applied, the roofs may experience leaks when the proper moisture barrier is not installed underneath the coping cap on parapet walls. Other typical problems with this system include inadequate head laps and backwater laps which allow moisture infiltration. Effects of backwater laps are leaks and blisters which can lead to roof failure. Even cold-applied Mod-bit systems can result in moisture infiltration as well as under application of adhesive which can result in poor lamination and roof leaks.


  1. Compatibility with all types of flat roofing applications.
  2. Resistance to the most extreme weather conditions such as high and low temperatures, rain, snow, ice and the freeze-thaw process.
  3. Life expectancy of SBS bitumen membrane is remarkable, even after ageing it retains its pliability and elasticity, making it the ideal flat roof solution.
  4. Dimensional stability is provided by the high quality SBS bitumen blend together with a high-performance reinforcement, enabling the waterproofing system to accommodate building movement.
  5. Installation is simple and can be achieved through a variety of methods; torch-applied, mechanically fixed or adhered, depending on the specification and suitability.
  6. Security and peace of mind for the building owner is achieved through the installation of a robust, multilayer, built up felt SBS modified bituminous waterproofing system.
  7. High resistance to mechanical damage and puncturing in comparison to alternative flat roof coverings. Extreme resistance variants are available depending on the traffic requirements of the surface.
  8. Excellent adhesion to the substrate on a flat roof installation (demonstrated by peel testing)
  9. Quality control is increased when installing factory produced rolls of SBS modified bitumen.

In most cases, when a bituminous flat roof system reaches the end of its service life, a single layer overlay can be installed over the top of the existing system to extend and renew the longevity of the waterproofing system.