Sometimes the most obvious advances in roofing technology can happen using the least visible of products. Cover boards have been used with flat roof systems for decades, starting with hot mopped and torch-applied asphalt systems to protect the underlying roof from damage during installation.
However, when single-ply roofs started to gain market share in the last quarter of the 20th century, demand for cover boards started to decline. Part of the trend away from cover boards was driven by the observation that single-ply roofs may not require a cover board to assure installation success. And some of the decline in the use of cover boards may have been a result of manufacturer specifications that did not require the use of a cover board to obtain a roofing warranty.