Built-Up Roofing (BUR)
Built-Up Roofing has been in use for more than 170 years, and was originally referred to as “composition roofing”. In this type of roofing system, a waterproof base sheet is first applied to the cleaned and prepped roof deck. Then, multiple layers (traditionally, 3-, 4-, or 5-plies) of roof “felts” are adhered together with a bonding agent, such as asphalt or coal tar. Finally, a protective surfacing layer is applied to complete the process. As one can surmise, the more intermediary layers that get applied, the greater longevity that the roof is expected to provide.