Born in the 1930s, when a consortium of companies was asked to develop a clear, tough, adhesive material that could be manufactured efficiently into automobile windshields, laminated glass has become a necessity in the arsenal of building products. Not only does it provide the means for creating soaring winter gardens and light-filled concert halls, but it also offers a solution to many of today's complex building demands. But it was not until relatively recently that authorities appreciated the fact that laminated glass plays a critical role as safeguard against natural hazards such as hurricanes.

In 1992, after Hurricane Andrew ripped through South Florida, Miami-Dade County was the first to act on the need for building code requirements that address impact resistant glazing products. Since then, a number of states along the Atlantic and Gulf Coasts have followed suit with the result that there are now hundreds of products on the market, and even more expected. Since laminated glass is a critical component of glazing systems designed to withstand hurricane-force wind and rain, an understanding and familiarity regarding its testing and wide-ranging benefits, is fast becoming essential.

Florida Hospital Waterman is a 204-bed, state-of-the-art acute care hospital serving the Lake County, FL community. Impact resistant windows provide patients with a view to the outside, while protecting them from severe weather. Courtesy of: DuPont Glass Laminating Solutions

A Wake-Up Call

The second most costly catastrophe in the U.S.- Hurricane Katrina is the first-Hurricane Andrew claimed 65 lives, destroyed or severely damaged 600,000 homes and businesses and caused more than $25 billion in property damage. Post-storm investigations by the Dade County Building Code Evaluation Task Force determined that the most significant hurricane damage was from the loss of integrity of the building envelope when the exterior of a structure was breached. And that the leading cause of the severe property destruction was window and door penetration caused by debris blown by the 145 mph winds. Subsequent reviews of damage documentation, insurance records, and computer simulations of building failures confirmed the decisive role of windborne debris in causing damage, reports Joseph E. Minor, P.E., F.ASCE in the Journal of Architectural Engineering, Vol. 11, No. 1, March 1, 2005. He also points out that the immediate result of failures of windows and doors was an increase in internal pressure which, in combination with overall roof uplift pressures, initiated a chain of events that included removal of roof sheathing, wind and rain entering the building and the beginning of progressive failure of the building frame.

As a result of the findings, Miami-Dade County and industry representatives worked together to develop requirements that addressed impact protection of building openings that directly applied to windows, doors, skylights, storefront and curtain wall systems. The South Florida Building Code with its hurricane mitigation provisions was implemented in September of 1994. In 2002 the improved structural portions of the South Florida Building Code were absorbed into the Florida Building Code as the High Velocity Hurricane Zone provisions, which are applicable within Miami-Dade and Broward Counties.