Modified Bitumen (Modbit) is a common flat roofing system that consists of asphalt with a variety of added rubber modifiers and solvents. Modbit membrane comes in rolls and its surface can include mineral granules, copper, aluminum, or aggregate. Modbit 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. Modbit is available in a variety of colors.