Built-up roof systems, commonly referred to as BUR, are a time-tested roofing solution consisting of multiple layers of bitumen, alternating with reinforcing materials like felt or fiberglass. These layers are built up to create a strong, durable membrane that provides excellent protection against water infiltration and extreme weather conditions.

BUR systems offer versatility in design, allowing for customization to accommodate various roof shapes and configurations. Additionally, they can be modified with surfacing materials like gravel or reflective coatings to enhance durability and energy efficiency. Despite the rise of newer roofing technologies, BUR systems remain a popular choice for flat or low-sloped roofs due to their proven track record of longevity and performance.