Built to Take the Hit
A Successful Impact Window Requires More Than Laminated Glass
By John Ryba
A machine fires a standard two-by-four against a residential window assembly. The lumber hurtles toward the window at approximately 35 miles per hour, directly toward the center of the glass.
The window withstands the impact and remains intact.
The test is repeated several times, also firing the lumber at the bottom corner and meeting rail. These are some of the rigors of testing impact-rated windows, and the procedure is designed to answer two questions: Can flying debris hit the window without creating a dangerous opening? And, after impact damage, can the whole window assembly survive repeated hurricane wind pressures without failing?
They’re important questions for homeowners and buildings throughout the Eastern and Gulf Coast regions of the U.S., where intensifying hurricane seasons have pushed local building codes into greater adoption of impact standards. According to the National Oceanic and Atmospheric Administration (NOAA), tropical cyclones have caused more than $1.5 trillion in damage in the United States since 1980, averaging $23 billion per event. Further, 2024 saw 27 separate billion-dollar disasters across the country with losses exceeding $1 billion each—an above average figure that may only grow in years to come.
According to the Federal Emergency Management Agency (FEMA), the adoption of strong building code requirements—including those specifying impact-rated performance for windows—can help avoid disaster-related property losses. In Florida specifically, FEMA estimates the state’s building codes help avoid more than $1 billion in annual losses, including millions from losses associated with hurricane winds. This is just one reason why impact windows are seeing uptake in more northern parts of the coast, as well as farther inland, and door and window OEMs have the chance to capitalize on rising demand.
Of course, developing impact windows is about more than market opportunity. It’s about protecting inhabitants from the worse consequences of flying debris.
Impact windows are one of a residential home’s best methods of protection from debris damage in hurricane- or wind-prone zones of the country. But, to meet growing demand for this technology, a whole-system approach to design, testing and component selection must be considered.
With all of this in mind, following is a look at what it takes to successfully develop impact windows and how you can put it into practice for your business.
Think Beyond the Glass
When considering the potential damage to a window during a major storm, it’s natural to first consider the glass itself. And, indeed, high-performance laminated glass is critical to the composition of an impact-rated hurricane window system. But it’s not the end of the story. This is in part because “impact rated” does not automatically mean “code compliant.” For example, per Miami-Dade County product requirements (typically considered the gold standard for hurricane-rated products in the U.S.), code-approved windows must satisfy both impact resistance criteria and design pressure criteria. To demonstrate reliable performance under such conditions—either in the lab or in the field—the individual components throughout the entire window assembly must pull their weight, including the frame, sash, glass (plus interlayers), locks, fasteners, anchors, sealants and more. The frame and anchorage must stay together to pass muster.
Framing and hardware are particularly important within these systems. Off-the-shelf options that satisfy the requirements of a basic system are not typically enough to withstand impact testing (or field performance). More robust framing systems, locks, keepers and tilt latches all contribute to the system’s ability to resist breaching under hurricane impact conditions.
OEMs must also consider operational needs in impact systems. Occupants on the U.S. coasts, of course, want their windows to open to welcome good weather into their interior spaces when there isn’t a storm knocking outside. So, consider a sash balancer, which must be able to compensate for heavier laminated impact glass, thicker glazing and heavier-duty frames and hardware, while delivering a desirable user experience. Further, during testing and real storms, a window’s performance depends on the sash being fully closed and locked. A weak or undersized balancer can let the sash drift or sit out of position.
Working with Qualified Partners
When developing a new impact window system, OEMs should consider that selecting the optimal mix of componentry is essential to creating the most value for both their business and for the consumer.
To those ends, the first step in developing a quality impact line is to consult with a project engineer. These experts should know the ins and outs of the specific code requirements in your target market and can help you dial in the right approach based on your existing window systems and favored profiles, glass and other components.
It’s also important to consider that obtaining the proper credentials for your impact window line is not inexpensive. If your designed system is lacking in a particular area, multiple rounds of failed testing expenses can add up quickly. To those ends, some component suppliers may be able to provide technical consultation, helping you to identify problem areas and how to rectify them. They may be able to guide you toward the right latches, balancers, locks and other hardware that can contribute to a successful system.
Impact windows are a critical part of residential building envelopes throughout the American East Coast, contributing to resiliency and occupant health and safety. They also represent a growing market opportunity for door and window OEMs doing business throughout these regions. Capitalizing here depends on identifying the right mix of components that can deliver reliable performance both in the testing lab and in the real world. The right partners can help you make it happen.
