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Volume 38, Issue 4, April 2003

Fenestration Focus

Market Opportunity or Necessary Evil?

The State of Impact-Resistant Windows

By Werner Lichtenberger

Disaster strikes: hurricanes, tornadoes, high winds and burglars. These enemies can strike homes and businesses alike. And like any adversary, they look for their target’s weak point.

Weather and safety considerations have prompted a window-market surge in the specification of impact-resistant (IR) windows. These specialty windows offer protection from strong winds, flying debris and would-be thieves. Impact-resistant windows feature either laminated glass, which consists of a a plastic interlayer between glass lites or shatter-resistant films.

Despite increased sales, some may argue that the IR window-market surge is driven partially by insurance companies and regulators.

Regulations and Market Opportunities

Certain regions effected by adverse weather, such as South Florida, have instituted building codes requiring the use of IR installations (glass, plywood or shutters) in new and remodeled structures. The codes may bring added construction costs as IR windows must pass inspection processes and also may have increased weight from laminated glass, requiring stronger balancer springs and technical anchoring systems.

Building codes specifying IR installations present stellar market opportunities for some window manufacturers, while crippling smaller businesses that cannot afford to respond to new regulations. Regardless of the growth potential, the industry should be wary of the laws of supply and demand. Manufacturers face high development costs for IR windows and may risk oversupplying the market, especially in areas that do not face regulations. Manufacturers also risk spending research and development dollars on systems that could be copied/modified by competitors.

In addition, IR window manufacturing requires an investment in lab testing, which is often beyond the reach of small companies. Missile impact tests involve firing 2- by 4-inch boards and roof gravel or ball bearings at great speeds at IR windows to determine their effectiveness. Because of the complex interactions of all components, IR window design is a trial-and-error process.
Insurance companies are also concerned with protecting their businesses and are raising rates in high-risk areas that endure frequent storm damage. An area which experienced devastation from Hurricane Andrew in 1992, such as South Florida, will have higher insurance premiums due to the likeliness of storms. These premiums may deter new-home ownership.

IR Benefits and Costs

Impact-resistant windows often prevent complete window breakage, lessening storm damage—water does not enter a building through the exposed cavity of a broken window and internal air pressure is stabilized, reducing the chance of a building’s roof being ripped off.
The cheaper protection method and more common alternative in disaster-prone areas is to use shutters and plywood to protect windows. These alternatives offer the same protection as IR windows, deterring development of IR technology in the industry. However, IR windows are more convenient because they do not require additional setup when a storm approaches.

The thermal properties of IR windows compared to traditional insulating glass (IG) units vary, and are dependent on climate. Tinted plastic interlayers in laminated IR windows allow for controlled blockage of the sun’s rays to provide energy efficiency in warm climates. However, IG units featuring laminated glass in cooler climates may sacrifice thermal performance as the air space between lites is diminished by the thicker glass and additional thickness of the plastic interlayer. To maintain adequate air space using a flexible warm-edge spacer, these IG units may require wider sashes and frames.

Growth Potential

Manufacturers looking to capitalize on the growth of the IR window market should invest in the wisdom of a knowledgeable consultant and testing lab to increase their likelihood of creating a successful unit. Engaging all of its window component suppliers will also help a manufacturer achieve better results.


Werner Lichtenberger, P. E., serves as special projects manager for TruSeal Technologies Inc., based in Beachwood, Ohio.