Assessing cover boards

A new evaluation technique is needed to determine cover boards' protective function


The North American roofing community has long recognized the benefits of including a cover board to increase a roof assembly's durability. In the past, the main purpose of cover boards was to protect against weather elements and minimal foot traffic. As a result, cover boards were evaluated for their material properties based on standards that were developed for individual board types.

Rooftops now are used as platforms for add-ons, such as photovoltaic or vegetative roof systems, which result in increased foot traffic, loads and stresses on roof systems. In addition to the increased physical burdens, there are more frequent extreme weather events, including hailstorms and heavy winds, that can result in debris and other items contacting roof systems.

The roofing industry has responded to this need by manufacturing a wide variety of boards made from asphalt, gypsum, cement, wood fiber, insulation and recycled products. These boards are placed above the insulation substrate to provide additional protection for roof systems. However, there continues to be damage observed to substrates. This leads to two fundamental questions: What is a cover board? And what should a cover board be contributing to a roof assembly?

What they do