Built Up Roofing (BUR) Systems

Henry Faulk Building, Austin, Texas

Built-Up Roofs (BUR) are the traditional approach to flat commercial or industrial roofing in North America. Multiple layers of felt with interply mopping of asphalt or coal tar are assembled in the field to “build up” a finished roof assembly. A heavy application of asphalt or coal tar, which is then covered with gravel, is the typical surface finishing to these assemblies, primarily for fireproofing and ultra violet protection.

These roof assemblies have a good life expectancy, normally in the range of 15 to 25 years. Built-up roofs were very popular until the 1970’s, enjoying better than 90% of the roofing market. For a variety of reasons, BUR’s experienced a decline in the market to approximately a 40% share in 1989. Significant improvements in materials and a better understanding of proper application techniques have resulted in significant gains in overall performance as well as market share. Approximately 55% of the commercial roofing market is now BUR.

Coal tar BUR’s are best utilized when roof areas have very low slope and ponding water is probable. Coal tar is completely impervious to ponding water, one of the few roofing materials that has this attribute. Coal tar also has a low melting point, which means in the summer months, the coal tar becomes fluid and will “self heal”.

Asphalt BUR’s are best utilized when roof areas have significant slope where the low melting point of coal tar might cause “slippage” of the membrane. Normally any roof system, which has in excess of 1/4” per running foot of slope, should utilize asphalt if the building owner wishes to utilize a built-up system. Asphalt roofs can also be built in a “smooth surface” installation if the finished surfacing of gravel is undesirable to a client.

Build Up (bur) roof systems which A. D. Willis Company Inc. installs include:
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