For more than a century, most commercial roofs were covered and protected with built-up roof membranes, or BUR systems. Still a reliable roof option today, this tried-and-true method of installing a watertight roof is created by alternating layers of bitumen and reinforced felt that is then surfaced for a final layer of protection.
As you work with your reliable Charleston roofing contractor to determine the best roofing system for your business, BUR systems may be discussed. Understanding BUR roofs, how they work and how they can fail will help you engage in an informed discussion about roofing options with your professional roofer.
There are many material options with BUR membrane systems. Although asphalt is the most common bitumen used as the adhesive and watertight layer, coal tar and cold-applied adhesive can also be used. Asphalt, of course, is heated and then mopped onto the felt layer or applied with a mechanical spreader. Coal tar is applied in a similar manner. Cold-applied adhesives are not heated, but contain solvents to keep the material fluid enough to be applied to the roofing layers.
Several choices also exist for the felt plies. Most of the felts used in the layering process are made of glass, polyester or organic fibers and are reinforced to provide strength to the roofing system. Most asphalt roofs use fiberglass felt layers for the best performance.
The final decision for BUR systems is the surfacing material.