Built-Up Roofing (BUR)
Built-up roofing is also known by BUR and is the most popular type of roofing material applied to low-slope roofs. It is made from alternating layers of reinforcing material and asphalt (bitumen) and is completed with a top coat of stone or gravel.
The use of BUR in low-slope or “flat” roofs is preferred because it constitutes a continuous sealed covering. The difference between BUR and roof shingles is that the shingles are not sealed and need a steep roof slope to discard water completely.
This type of roofing is not new, but the material and its base have developed during that time. Current built-up products include a rigorous insulation layer for increased energy efficiency.
Most built-up roofs are made of three components: bitumen supply, ply sheets, and one or more surfacing materials that can be stone or gravel.
The bitumen can be either “hot,” implying it is heated so that it dissolves during installation, or it can be “cold,” which resembles an adhesive.
Cold BUR can be spattered or applied with a type of mop, and it does not release toxic residues through the application. The cold built up is not conditioned by weather and also grants better performance than the hot one.