Modified Bitumen (Mod-Bit or MB) is designed for buildings with a low-slope or flat roof structure and is used in installations like those of Built-Up Roofing (BUR) systems. While BUR systems’ layers are built on site, Mod-Bit is a roofing membrane that consists of plastic or rubber polymers and asphalt layers constructed at the manufacturer.
The most commonly installed Mod-Bit roofing system is Styrene-Butadiene-Styrene (SBS) which has superior flexibility for expansion and contraction. The other type of Mod-Bit roofing system is Atactic Polypropylene (APP) which has superior aging properties to SBS.
Modified Bitumen Roofing systems consist of five layers:
- Modified Base Sheets or Piles
- Modified Bitumen Membranes
- UV protection and weather-resistant surfacing
Advantages of Mod-Bit to BUR include these:
- Lighter weight
- Does not require gravel/aggregate
- Typically faster installation times
- Light-colored surface reflects heat and cuts energy bills
- Can handle wider temperature extremes
- Factory-controlled manufactured membrane