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May  2004

Hurricane Force
New Code Requirements Usher in Laminated Glass Products

by Craig A. Shutt 

Homebuilders and architects are discovering that upgraded codes (particularly in coastal areas concerned with hurricane damage) require new approaches for specifying glass areas in doors, windows and skylights. Fortunately, products are available and more will be coming as the need expands beyond Texas and Florida to include coastal localities up through Maine and even into Canada. 

“The new codes are requiring higher standards of protection from windborne debris and impacts for glass used in exterior openings. Builders and designers must be aware of the changes and provide the products that are necessary,” said Alan Campbell, president of the Window and Door Manufacturers Association in Des Plaines, Ill. “Fortunately, window, door and skylight manufacturers have responded to the need and have produced a wide range of product lines that will meet the code requirements in every region.”

The changes began with tighter regulations in Florida approximately five years ago, and they have become part of the new International Residential Code and International Building Code now being used in many other areas. The codes were adopted by Texas municipalities and were expanded in 2003, when the Texas Department of Insurance (TDI) adopted new codes and began to require buildings seeking windstorm insurance coverage through a state program to meet certain windborne-debris requirements. Now, more regulatory bodies along the coast, including those in Virginia, New Jersey and in New York State’s Long Island, have adopted the codes, and builders and architects must find products that meet the enhanced standards.

“Hurricane glass, per se, doesn’t exist,” said Tom Kopec, North American architectural manager for DuPont. “The key is to create a system that meets the standard for hurricane protection. The system comprises the combination of glass, frame and the way the glass is sealed into the frame. The glass has to work in an entire system.”

Protection Methods
The requirement can be met in several ways, including shutters or wood structural panels in addition to laminated glass, code experts say. But laminated glass offers benefits that add appeal, said Kopec. 

“Homeowners are very picky about what they want in their homes,” he said. “The products need to offer performance, quality and aesthetics, because the home is the owners’ ‘face’ to the world. It’s possible to combine all three of those properties into one product, but not everyone does it. The product has to continue to look good over time—not just to meet the building code but because that’s a standard of the residential market.”
Cost and homeowner preference can determine whether laminated glass or other types of protection is used, according to Paul Bove, a TDI staff engineer. Lower-priced homes may try to save costs by using removable panels, while high-end homes tend to feature laminated glass in windows and doors or high-quality shutters. There also are variations by region, he notes, as Florida tends to use more laminated glass or proprietary shutter products while plywood panels are being used predominantly along the Texas Gulf Coast.

Laminated glass can offer additional benefits beyond impact resistance and aesthetics. A key advantage is that the extra layer of material dampens sound vibrations, creating lower sound transmission from outside. Lamination also provides some added ultraviolet protection and a passive system that doesn’t need to be activated, as shutters or panels must be, according to manufacturers. 

“Many of these homes in coastal areas are rental or vacation properties,” said Steve Berg, manager of specialty products at Andersen Windows. “The owners are not always there to put up protection if it’s needed.” 

There’s also the need to store panels when not in use, adding not only labor but space to the requirements. Rolling shutters that are stored above the openings can detract from the home’s image. Hurricane season includes the summer months when snowbirds, who may live in tropical climates during the winter, are back “up North,” adding another benefit to the passive protection afforded by laminated glass systems.

Thermal Breaks 
Add Challenges
Meeting the requirements in Northern states offers more challenges, adding to the need for energy efficiency as well as glass protection. The combination of two lites of glass to create an internal air space serving as a thermal break along with a lamination layer creates a window with considerable weight. 

At Pella, where many products feature an internal, removable window lite, adding the lamination was easy, said Joe Hayden, certification engineer. Even so, the lamination creates a lite that is ½- to 9/16-inch thick. 

“We had to develop a new line of products to handle the heavier weight, but the differences were minimal,” he said. “These consisted primarily of beefing up the frame and hardware to secure the window as well as heavier glass stops and supports to secure the glass in the frame.”

“There have been several changes in how impact glass is designed and glazed due to the thickness requirements of insulating impact glass versus single glazing,” said Jim Krahn, manager of advanced research at Marvin Windows and Doors. “These changes include an increase in the thickness of the laminated glass panes and slightly smaller air gaps than standard IG units.” 

Marvin’s glass lite thickness and air gaps are selected to meet all requirements. 

“The goal is to provide the required impact protection while still being able to fit the thicker glass units into the existing sash glazing cavities and comply with the energy code requirements,” he added.

The heavier products require added care in handling and installation but there are no differences in how they are installed. Availability of products to meet whatever design style and code requirements builders and architects seek shouldn’t be a problem. Andersen’s Berg, for instance, said his company offers 700 products in 28 lines that are available with laminated glass. 

As the lines expand, new techniques are being added to create options that can’t be matched with regular glass. Dupont, for example, has created a system in which architects or builders can provide a digital image that is printed onto the lamination, creating a photographic image inside the glass. 

Other techniques and benefits will be added as the products gain in popularity. Berg noted that use could also grow inland, as designers realize how the glass can cut noise pollution. The future of architectural design may include added protection from blasts or other types of impact, providing additional market opportunities.

“Right now, outside of Florida and the Gulf Coast, which have been exposed to these products for some time, architects are looking for information and benefits,” Berg said. “They see the costs, but they don’t know all the alternatives available and the advantages offered. So they’re on a fact-finding mission. As the codes—and their enforcement—become more widespread along the coast and people realize the benefits, I expect these products will be used more.” 

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