Modified bitumen is an advanced asphalt-based roofing system reinforced with polymer modifiers that improve flexibility, strength, and weather resistance. It’s installed as rolled sheets that are typically heat-welded, cold-adhered, or self-adhered to create a durable, watertight membrane. This type of roofing combines the reliability of traditional built-up roofing with modern materials that offer superior flexibility and UV resistance. Which makes it ideal for flat and low-slope roofs that face constant exposure to sun, standing water, and temperature swings.