What characterizes a built-up roof (BUR)?

A built-up roof (BUR) is characterized by its construction of multiple layers of asphalt or coal tar-saturated felts. This layering is a fundamental aspect that provides durability and waterproofing for the roof. BURs are applied in a systematic way, often involving alternating layers of felt and asphalt, which becomes a solid membrane once completed. This process helps create a resilient roof that can effectively shed water and resist the elements.

This roofing type is primarily used for low-slope or flat roofs, which makes it unsuitable for steeply sloped roofs where different roofing materials and techniques would be more effective. The composition of BURs is designed to enhance weather resistance and longevity, distinguishing them from roofs made solely of simpler materials like asphalt shingles. While maintenance may be required over time, particularly to ensure the layers remain intact and effective, the emphasis of a BUR’s design is on its layered construction rather than its maintenance needs.