According to the Institute for Business and Home Safety (IBHS), roof cover damage continues to be the largest, most frequent source of non-surge related failures related to hurricanes¹. In response, roof covering manufacturers have provided a multitude of products that have demonstrated through independent testing to be able to withstand design event forces. However, it is apparent in the wake of recent windstorm events that much is lost in translation between the idealized laboratory setting and an actual constructed roof. This article will provide a brief review of the current codes, design, and selection process. It will also present a number of common construction-related defects that result in the loss of millions of dollars annually.

The selection of the roof covering in a hurricane-prone region would likely start with the locally adopted building code. For most of the U.S., the building code is likely a recent version of the International Building Code² with local- and regionally specific, amendments. Some jurisdictions—Florida, for example—have specific codes that apply. The purpose of the code is to set a minimum standard of construction and design for the purpose of life safety. It typically does not purport to address other aspects of the functionality of the roof that might include resistance to water infiltration, service life expectations, hail resistance, and other functions that the facility owner may also require. Another distinction to make is that codes, especially those related to commercial buildings, have become less prescriptive and more performance-based in the last few decades. The code dictates the design criteria but not the number of fasteners per square foot.

Performance-Based Guidelines
Once the basic life-safety design criteria is established, local municipalities and insurance requirements take the design process further, by requiring the selection of assembly that has shown through independent laboratory testing to have a particular resistance to applied wind loads. It is the manufacturer of the specific assembly that undertakes to have it rated by third-party testing. The tested and rated assembly is specific with respect to the materials, attachment, and configuration. Any variation in, say, the type of fastener used, would constitute a different assembly that would require its own rating. Therefore, upon selection of an assembly that is meant to meet building code, local municipality, and, in some cases, insurability requirements, it becomes imperative to closely follow the manufacturer’s recommendations for the installation of the assembly.