A built-up roof consists of multiple piles of roof felts laminated together with bitumen. Built-up roof material can consist of bitumen-saturated felt, coated felt, polyester felt or other fabrics. A surfacing is generally applied and can be asphalt, aggregate (gravel or slag), emulsion or a granule-surfaced cap sheet.
Built-Up Roofing is one of the oldest and most reliable ways of installing a new roof. It was first known as composition roofing and started in the 1840’s. B.U.R.’s come in two basic types, asphalt and coal tar, and three basic components:
- the waterproofing component
- the reinforcing component
- the surfacing component which is used to protect the other components from the elements
The roofing membrane is protected from the elements by a surfacing layer, either a cap sheet or gravel embedded in bitumen or a coating material. The most common surface for a BUR system, particularly in the west, is a fiberglass mineral surfaced cap sheet. The west represents 40 percent of the fiberglass cap sheet market. It offers a number of advantages. It has a white granular look, it is cost effective, and is relatively maintenance free.