Built-Up Roofs
Most of the roofs currently installed on low sloped (flat) roofs in California are Built-Up Roofs. Theses roofs consist of multiple layers of fiberglass roofing felts installed with either hot asphalt or asphalt based cold adhesive. They can have either gravel surfacing, cap sheet surfacing or coated surfacing.
One of the advantages of built-up roofs is that they are generally considered to be less expensive than other types of systems. They work well on buildings that require heavy foot traffic. They are a good option on buildings where tenant improvements are likely to be performed.