What is one of the oldest and still popular surfacing materials for a BUR roof?

A flood coat of bitumen and an adhered aggregate surface is one of the oldest and still popular surfacing materials for a Built-Up Roofing (BUR) system. This method involves applying a thick layer of hot or cold bitumen over the top layer of the roofing system, followed by embedding aggregate such as gravel or stone into the bitumen. This provides several benefits: it enhances protection against UV radiation, adds weight to resist wind uplift, and serves as an effective barrier against moisture and weathering.

Historically, this method has stood the test of time due to its durability and proven performance in various climatic conditions, making it a reliable choice for flat or low-sloped roofs. The aggregate surface not only offers aesthetic appeal but also improves the roof's longevity and represents a traditional approach to BUR systems that continues to be effective and widely used in modern applications.