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Impact- Resistant Windows

The hurricane season’s full force was demonstrated mid-year 2017 when Hurricanes Harvey, Irma, Maria, and Jose ripped through the Houston area, most of Florida, and the Caribbean, causing hundreds of billions of dollars in damages and inflicting harm on millions living throughout these regions. 

Unfortunately, no one yet has found the perfect defense for Mother Nature. The best anyone can do is heed the warnings and prepare for the worst with the tools, technology, and knowledge available.

UPGRADING BUILDING CODES

In recent years, both federal and state governments have joined with local authorities to greatly upgrade the codes and regulations governing design and build efforts in regions commonly besieged by severe storms ranging from hurricanes and tornadoes to Nor’easters. As The Wall Street Journal recently reported about the effects of Hurricane Irma in Florida, one pattern is beginning to emerge: structures that were built to the stricter building codes seem to have fared better.

For example, in 1992, Hurricane Andrew ravaged the Bahamas and Florida with sustained winds topping more than 160 mph. Recognized at the time as the costliest hurricane ever to reach U.S. shores, the Category 5 storm struck with such ferocity that buildings were literally torn from their concrete foundations. In the aftermath, more than 63,500 homes were destroyed, nearly 125,000 others were damaged, and 65 people lost their lives. After conferring with engineers and economists, the Federal Alliance for Safe Homes, a leading advocate for strengthening homes and safeguarding families from natural and manmade disasters, concluded that these damages were likely intensified by the flawed building codes in place at the time.

As a result, in 2002, Florida enacted one of the nation’s strongest set of building regulations. Among the provisions were requirements for stronger fasteners to secure roofing and the installation of missile-impact resisting glass to better protect windows from wind-borne debris hurled at extreme velocities during hurricanes and other storms.

THE DAMAGE OF WIND

Although it may take years to truly assess, Florida International University researchers have estimated that Hurricane Irma’s severe wind speeds, which were estimated at 130 mph at landfall in the Lower Keys, may have caused as much as $20 billion in damages on its own. That’s because unsecured building openings like garage doors and windows are especially susceptible to breaches from the intense wind pressure and blowing debris that can be propelled into buildings at more than 100 mph. Once pierced like the seal on a bottle, storm gusts are then free to burst into the building through these openings and literally tear the structure apart from the inside.

To prepare for these occurrences, the Federal Emergency Management Agency (FEMA) and other local authorities have offered guidelines designed to shield buildings from avoidable storm damage. According to FEMA, windows should be: 1) correctly designed and anchored to resist wind pressures, 2) adequately protected to resist windborne debris, 3) sufficiently flashed and weather-stripped to limit water infiltration, and 4) appropriately selected to resist local conditions. In addition, FEMA’s website says the most effective solution is impact-resistant glazing systems. These systems provide “in-situ” protection and require no human action or involvement after installation; the protection system is in place at all times and does not need to be installed prior to storm events. Further, these systems do not need to be closed, lowered, or installed like storm panels or shutter systems.

Next, every building located in areas frequented by severe storms, especially those situated in High Velocity Hurricane Zones, should be properly evaluated for their ability to withstand strong hurricane-force winds. As mandated by the American Society for Testing & Materials (ASTM) and the American Architectural Manufacturers Association (AAMA), impact-resistant windows are required to undergo a stringent series of tests.

IMPACT-RESISTANCE FACTOR

The ASTM E1996 impact-resistant test starts with an 8-foot long, 9-pound 2×4 being fired from a cannon into the window. Next, the window is subject to 4,500 positive and 4,500 negative pressure cycles at 20 to 100 percent of its design pressure rating to simulate the high-pressure winds created by hurricanes. To comply with ASTM E1996, three samples must pass this stringent test.

“To ensure compliance, impact-resistant windows are designed with a heavy-duty frame construction that ensures durability and endurance during severe storms,” says Ray Garries, VP, Engineering & Innovation, MI Windows. He adds that in addition, they utilize laminated glass, which consists of clear layers of polymer sheets laminated between the layers of glass to provide protection, strength, and rigidity. Common in automotive windshields, laminated glass adds strength to the glass without impeding visibility.

“Developed to accommodate wide-ranging architectural designs with a stylish selection of single-hung, single-slider, picture window, specialty shapes and patio doors, not all storm-resistant windows are the same,” explains Garries. “While impact (laminated) glass is used on all, the frames of impact windows can be made with many different materials, including vinyl and aluminum.”

An additional benefit of impact-resistant windows is improved sound transmission, which occurs due to the thickness and embedded poly material within the laminated glass. “Structures featuring impact-resistant windows are quieter than those built with non-impact-resistant glass, a feature that pays dividends all the time—even on calm, sunny days,” says Garries.

CONCLUSION

Although many builders may be reluctant to invest in impact-resistant windows, which can be three times the cost of standard windows, the value of such products is frequently recouped in regularly besieged storm areas. When it comes to insurance and purchasing protective policies, one hopes to never file a claim. The same is true with hurricane-resistant products. Hopefully, they’ll never be fully tested, but they will always be in place to protect against severe threats when they arise.

ABOUT THE AUTHOR

Josh Williard is a product manager with MI Windows & Doors. With plants in Pennsylvania, Texas, and Arizona, MI Windows and Doors offers a broad spectrum of windows and doors backed by exemplary customer service. For more information, visit www.miwindows.com.

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Modern Contractor Solutions, July 2018
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