Post-Katrina Study Notes Durability of Asphalt Roofing

The Hurricane Katrina Wind Investigation Report, recently released by the Washington, D.C.-based Roofing Industry Committee on Weather Issues (RICOWI) Inc., provides insights into installation techniques that can enable asphalt roofing systems to better withstand major windstorms.

According the Reed Hitchcock, executive director at the Asphalt Roofing Manufacturers Association (ARMA), also based in Washington, D.C., "Such surveys allow the industry to evaluate the performance of materials and designs in real-world construction subject to extreme conditions created by nature."

The mission of the Wind Investigation Program (WIP) is to investigate the field performance of roof assemblies after major windstorm events, factually describe roof assembly performance and modes of damage, and formally report results of investigations and damage modes for substantiated wind speeds.

Hurricane Katrina made landfall as a rare Category 4 Hurricane (with winds from 131 to 155 miles per hour). In its aftermath, WIP teams focused on Coastal regions in Mississippi, which experienced damaging winds. When major damage was noted, it was typically due to poorly attached system components such as decks or cementitious wood fiber (CFW) panels. The report results stressed that all members of a composite system must be adhered or fastened to resist uplift.

On the whole, though, the investigators' results were positive. "Considering the range of installation quality, we are generally pleased with the wind performance of the asphalt roofing materials at extreme wind speeds, for both the low-slope and steep-slope applications," says Hitchcock. "The lessons learned," he continues," are that substandard system designs and poor installation practices cannot be tolerated in hurricane zones or any areas prone to extreme windstorms."