Material Composition: BUR systems consist of multiple layers of bitumen (asphalt or coal tar) and reinforcing materials. The layers are alternated between bitumen and reinforcing felts, commonly made of fiberglass or organic materials such as felt or rag paper. The number of layers can vary depending on the specific BUR system and desired performance.

Layering and Waterproofing: The multiple layers in a BUR system provide redundancy and enhanced waterproofing. The bitumen layers act as a waterproofing agent, while the reinforcing felts add strength and stability to the roof system. The layers are typically hot-applied, with each layer being mopped or spread over the previous layer.

Gravel or Surfacing: BUR systems often have a top layer of gravel or mineral granules embedded in a flood coat of bitumen. This layer serves as a protective barrier, shielding the underlying layers from UV radiation, extreme temperatures, and physical damage. Alternatively, a reflective coating can be applied as a surfacing material to enhance energy efficiency.

Durability and Longevity: BUR systems are known for their durability and long lifespan. When properly installed and maintained, they can last 20 to 30 years or even longer. The multiple layers provide added protection against water infiltration, fire resistance, and resistance to punctures and other types of damage.

Maintenance: Regular maintenance is important for BUR systems. Inspections should be performed to identify any signs of damage, such as cracks, blisters, or loose gravel. Proper drainage should be maintained, and any necessary repairs or maintenance work should be conducted promptly to prevent further damage.