What are the two main types of bitumen used in BUR systems?

The two main types of bitumen used in built-up roofing (BUR) systems are asphalt and coal tar. Both materials serve as essential components in providing waterproofing and protection for roofing systems.

Asphalt is a petroleum-based product that is commonly used due to its availability, cost-effectiveness, and excellent weather resistance. It is versatile and can be modified with additives to enhance its properties, such as flexibility and UV resistance.

Coal tar, on the other hand, is a byproduct of the carbonization of coal. It has a long history of use in roofing due to its excellent resistance to fire, water, and chemicals. Coal tar provides a robust protective layer, though it can offer a more challenging application process and has different handling and exposure considerations compared to asphalt.

Both asphalt and coal tar are integral in the durability and performance of BUR systems, as they create a waterproof seal that protects the underlying structure from moisture and environmental damage.