Retrofitting Commercial Structures with Laminated Glass to Withstand Hurricane Effects

There is an enormous inventory of buildings in the United States. The majority of these buildings have not been designed to resist hurricane effects, namely high winds and windborne debris.

Commercial structures have a history of damage during previous hurricanes. Many large buildings in downtown Houston, Texas suffered extensive glass breakage during Hurricane Alicia in 1982. This was the first documented instance of windborne debris causing significant glass breakage in an urban area. Before Alicia, it was thought that high winds alone were responsible for hurricane damage. However, recently there have been several more instances of glass breakage during hurricanes have occurred, including the Kendall area in Dade County, Florida during Hurricane Andrew in 1992.

While mitigation efforts for newly constructed buildings are very important, this activity only benefits a small percentage of the built inventory. The vast majority of the built commercial building inventory is not protected. Without retrofitting, it will take many years before a significant percentage of commercial buildings are protected, even if all newly constructed buildings were designed for hurricane effects.

Protecting commercial structures from hurricane elements, namely wind and windborne debris, requires unique considerations. Many buildings have glass areas too large to accommodate shutters. Even if shutters can be employed it may be impractical to install them in advance of a storm. Often the best solution for a commercial building is to use impact-resistant laminated glass. With laminated glass, there is no special preparation required in advance of a storm as the protection is always in place. And, it provides invisible protection because it appears as ordinary window glass.

The use of laminated glass for hurricane protection requires special designs. Laminated glass is often thicker than ordinary window glass and it must be attached or anchored to the window frame so it remains in place, if broken. The challenge for retrofitting commercial windows with laminated glass is to find a cost-effective method that does not require replacement of the framing as well. This paper will present methodology for a cost-effective retrofit using laminated glass and the existing window frames.