Chances are that if you know who George Harrison was and what his contribution to culture was you are aware of built-up roof systems. Whereas, if you know who Snooki is and why she matters you probably have never seen a built-up roof system applied.
Built-up roof (BUR) systems have been on the United States commercial roofing market since the late 1800s. They were long considered conventional roof systems. The documented use of bituminous products such as coal tar and asphalt as waterproofing products dates back thousands of years. In the past two decades the use of BUR systems has continually declined. Coal-tar BUR systems now comprise less than 1 percent of the market, while asphalt BUR systems struggle to reach double-digit percentages on an annual basis.