west palm beach
Considerable research has been done to evaluate both hurricane damage and its causes. The research indicated that the failure of windows and doors was a leading cause of total building failure during high-wind events. Further, it became evident that windows and doors very often fail not as a result of wind forces themselves, but due to the impact of flying debris. Consequently, a concerted effort was made to develop products that would help shore up these structural vulnerabilities, and impact-resistant windows and doors are the latest products to have evolved from this research.

Impact-resistant windows meet the same test standards as shutters and offer a range of additional benefits, usually at a cost comparable to most high-quality windows. The benefits include passive protection that, once installed, is always in place; enhanced 24-hour security, considerably improved outside noise abatement; and 100% protection from ultraviolet light, which is the portion of the spectrum that can contribute to color fading in furnishings.

When Rob Thompson's West Palm Beach house (a 2001 This Old House project) was built in 1925, there were no building codes addressing the issue of hurricane protection. Now, however, Palm Beach County building codes require hurricane protection systems for all new construction and major renovations. Rob had a decision to make. Hurricane protection systems come down to two basic options: shutter systems, or impact-resistant windows and doors. And since Rob wanted to preserve the look of the home without shutters, he chose to go with the latter, selecting single-hung windows, casement windows, architectural fixed glass and French doors as replacement products.

It hasn't been without a journey, however, that hurricane-resistant windows and doors arrived at the state of the art available for Rob's renovation. In the initial research and development following Andrew, storm shutters were the first area to be explored. There were several different kinds that worked as intended, but all had a few drawbacks. Both roll-down and accordion shutters don't tend to look very good attached to the outside of a home, and also are expensive. Panel shutters, on the other hand, are a less expensive option and require less obtrusive mounting hardware, but their installation and removal are labor-intensive, and a significant amount of space is also needed to store them.

In light of these challenges, glass manufacturers began investigating their own solutions. In the end they resorted to an old technology, born out of safety issues that arose in the automotive industry in the 1930s. It turned out that laminated glass had the potential for solving the problem. Most automotive windshields use laminated glass consisting of a 3/100-of-an-inch plastic interlayer sandwiched on each side by regular glass. The challenge was to develop this glass product further in order to meet new hurricane protection requirements put in place after Andrew. The Miami-Dade Building Code and Compliance Office initiated a rigid standard of test protocols for impact protection in windows and doors. Eventually, by increasing the interlayer thickness threefold to 9/100 of an inch, two companies developed glass products that could survive the Miami-Dade test protocols. Although the glass in hurricane-resistant windows and doors does break when impacted at high velocities, it is not penetrated, and because the shattered glass adheres to the plastic interlayer, the hazard of flying shards is practically eliminated.

The Miami-Dade test protocols consist of two impacts on windows and four impacts on doors by a nine-pound two-by-four traveling at 50 feet per second, followed by up to 9,000 cycles of positive and negative wind-loading. After the glass companies developed a component to pass the tests, the next step was to develop window and door assemblies that would pass these same tests.

Since then, a complete product line has been developed that, combined with the glass component and proper installation methods, can successfully meet the Miami-Dade test requirements. When installed in a one- or two-story residential dwelling, these window and door products can now be reasonably expected to withstand winds up to 130 miles per hour, including impacts by flying debris. Subsequent tests have also led to code changes in Florida, Texas, and the Carolinas. Finally, given the violent nature of these tests, it was necessary to develop installation methods that would provide adequate anchorage to the structure to allow the products to perform correctly. In fact, this is where a problem developed with Rob's house. I inspected the 75-year-old wood casement windows and found they were in fairly poor shape. There was a lot of dry rot, termite damage, and no solid structure to anchor to. Fortunately the general contractors were able to use two-by-fours to thoroughly reinforce the openings and provide correct anchorage for all Rob's replacement products.

When the winds won't come a-blowing in south Florida, Rob will know his house has the windows to stand up to them.

Dave Olmstead of PGT Industries inspected and consulted on the windows at the West Palm Beach house, a 2001 This Old House project.
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