A continuous, multi-layered roofing membrane system used on flat or low-sloped roofs. It is constructed by applying alternating layers of hot asphalt or coal tar (bitumen) and roofing felts or fiberglass mats. The final top layer is typically coated with gravel, slag, or a mineral cap sheet to protect the membrane from UV degradation and foot traffic.
Heard on the job
The core sample shows this built-up roof has four plies of felt under the gravel stop.
Insider tip
Finding the exact source of a leak on a built-up roof is notoriously difficult because water can travel horizontally between the plies before showing up inside the building.
Also heard as
- tar and gravel roof
- BUR