Which material is commonly used in built-up roofing systems?

Built-up roofing systems are characterized by their use of multiple layers that provide durability and waterproofing. The primary materials employed in these systems typically consist of layers of asphalt and felt or fiberglass mats. The asphalt serves as a waterproofing agent, while the felt or fiberglass mats act as reinforcement, adding strength and stability to the roofing structure.

This traditional roofing method is well-regarded for its ability to create a seamless, monolithic surface that effectively shields the building from rain, wind, and other environmental factors. The process of applying multiple layers creates a thick, robust roofing assembly, which is especially advantageous in flat or low-slope applications.

In contrast, the other options represent different roofing technologies or systems. For instance, wood panels and shingles are more often associated with steep-slope roofing systems, while metal sheets and rubber membranes are typical of other roofing designs that do not match the built-up configuration. Single-ply membranes, also, have different construction methods that do not include the layered assembly characteristic of built-up roofing. Therefore, the use of asphalt layers combined with felt or fiberglass mats uniquely identifies built-up roofing systems.