Built-up roofing is also known as what type of roofing?

Built-up roofing, commonly referred to as tar-and-gravel roofing, consists of multiple layers of bitumen and reinforcing fabrics, typically finished with a layer of gravel. This type of roofing system is favored for its durability, waterproof properties, and ability to withstand UV exposure. The layers of bitumen create a strong, watertight seal, while the gravel layer adds protection against physical damage and helps to reduce heat absorption, contributing to energy efficiency.

The term "tar-and-gravel" aptly describes the two primary materials used in its construction: the tar (or bitumen) acts as an adhesive that binds the layers together, and the gravel provides a protective top layer. This system is particularly beneficial in flat or low-slope roofing applications. Understanding the characteristics and benefits of built-up roofing is essential for recognizing how it serves specific needs in roofing, distinct from other types such as metal roofing, single-ply membranes, or modified bitumen systems.