Presented by Bas Baskaran, PhD, PEng, of NRC, and David L. Roodvoets of DLR Consultants

As insurance claims increase, wind-induced failure is a major concern for building enclosure designers. To understand the weakest links on the roof assembly, the Roofing Industry Committee on Weather Issues (RICOWI) launched a Wind Investigation Program (WIP) in 1996. WIP missions are as follows:

1. To investigate the field performance of roofing assemblies after major wind storm events
2. To factually describe roof assembly performance and modes of damage
3. To formally report the results for substantiated wind speeds

Keys to the RICOWI investigations are teams that are balanced, unbiased, and trained in wind damage assessment. Teams typically are made up of a manufacturer, a roof consultant, and a university or insurance organization representative. Several WIP investigations have been completed over the past 20 years. This presentation focuses on the performance of low-sloped roofs. Among others, three weak links were found critical in the failure of the roofing systems, namely:

• Securement of roof edges
• Role of rooftop equipment
• Integration of roof/wall interface

Each of the above weak links is scientifically analyzed, followed by field observation. Correlations are developed for roof wind design. In addition, wind design data from the North American codes of practice are also calculated and compared to show the impact of science and field observation on durable roof design. With these illustrations, this paper offers recommendations to advance the roof system design for hurricane-prone regions.