The Effect of Impact Resistant Windows

By Susan Tamme

On August 24, 1992, a Category Five hurricaneHurricane Andrew—advanced toward South Florida. The enormous storm left a 25-mile-wide arc of destroyed homes, toppled trees and power lines, and flooded streets. That storm changed how homes were to be built and designed, bringing together a committee in the Florida legislature to study how the state could prepare for another, similar hurricane. This produced what would eventually develop into the Miami-Dade Building Code for Southeast Florida. As a result, the state adopted the Florida Building Code as its first statewide code in 2002, requiring new structures to be built to withstand hurricane-force winds and to have roofs and shutters or impact-resistant glass to protect openings. It also prompted insurance companies to mandate stricter requirements for structures in Florida seeking coverage. The effect of those new codes and guidelines were clearly visible with each subsequent hurricane making landfall in the state of Florida.

Since 1992, stricter building code amendments have been constantly changing, requiring even more fortification for buildings to reduce the loss of life and property. But what impact has this structural safety net against hurricane-force winds had on tactical considerations by fire officers during a fire?

An impact resistant window is composed of two or three panes of an impact or resistant glass in residential structures of up to 7/16-inch thickness, which sandwiches an inner layer of polyvinyl butaryl and is set in an aluminum or vinyl frame. High-rise and commercial structure windows may be up to 1¼ inches thick. Window material, thickness, and design will vary between manufacturers.

Impact resistant windows are also reinforced into the window frame during installation. Instead of using several one-inch metal screws to install the standard window frame, impact resistant windows will be installed with three-inch fasteners and many screws which MUST attach at least 1¼ inches into the substructure. An impact resistant window looks and is manufactured similar to a standard plate glass window; when struck by flying debris during a storm, it will stay in one piece, protecting the building from the devastating effects of high winds. It will NOT be readily noticeable whether a building or structure has an impact resistant window, especially in residential structures which are not prefire planned.



WeatherTite Windows, a local Tampa distributer of impact resistant windows, and PGT Industries, the nation’s leading manufacturer and supplier of residential impact windows and doors, partnered with Tampa (FL) Fire Rescue to investigate and refine a method for making entry (and exit) through an impact resistant window. Entry through or around the window framing or wall was not considered because of the reinforced installation requirements. Several window props were prepared, and firefighting crews used a variety of power and hand tools to identify the best practices for breeching impact resistant windows for entry and rapid exit. There were single hung, picture, and casement window openings of various sizes for our training/evaluation. Prior to the exercise, it was determined that impact resistant windows are manufactured to withstand the force of a large missile impact and, therefore, the standard firefighting forcible entry methods would largely be ineffective.



The fastest and most effective tool for a firefighter confronted with impact resistant windows would be the Fire Rescue Chain Saw with a carbide chain. The objective, as with any entry, should be to use the least amount of force (physical energy) to accomplish the task.

With this in mind, the first cut should be a vertical, downward cut from the highest point along the frame. Next, cut horizontal along the window’s top edge, as high as the firefighter can reach. The remaining cut will follow the remaining horizontal window frame edge (three cuts). This window can now be pushed inward to release the fire gases.

Another effective cutting tool would be the K12 Circular Saw or Fire Rescue Rotary Saw; this saw is heavier and more difficult to maneuver when using above your head. Cutting the window follows the same method as with a chain saw. A battery-powered reciprocating saw can be used with a sharp, longer toothed blade. When using a reciprocating saw, a purchase point is necessary to begin cutting. Start cutting as high as possible, and follow the frame with rounded corners. Once the cutting of the glass material is completed around the frame edge, the window can be forced inward with a hand tool. This firefighting equipment is generally found on truck companies and not with the first-arriving engine units. These methods are ideal; if you have those power tools readily available.



What happens when you need to evacuate a structure and discover that the windows are impact glass? You will have to rely on your hand tools. The standard complement of a halligan or ax for normal firefighting operations is a start, but you will need to find a cutting tool.

A pocket rescue knife or a seat belt cutter located on your helmet or Glass Master is a suitable option. After making a purchase point, use a knife with a serrated edge to cut through the laminate (right).

A standard pocket tool and a window saw performed with equal results. You may only need to make a U-shaped cut to expose the lock mechanism.


Pike Pole

If a pike pole is the only tool to which you have access, you should be able to penetrate the window. However, it will be difficult to remove the window without a cutting edge.



Attacking the mullion is one option firefighters have here. Use a sledgehammer, a halligan, or an ax to attack the mullion (left). Using irons and/or a sledgehammer can easily compromise the mullion, which is held in place with a couple of screws. Once the mullion is removed, the pane can be moved forward, with little effort placed on the impact glass.

Training and repeated experience have taught us that, when faced with a window after “trying before prying,” our instinct will be to break the glass. Impact resistant windows will complicate what we know about forcible entry; they will NOT give into the brute force of our tools. Typical residential structures of the future will be more difficult to access, especially in areas of the country where the threat of hurricane force winds have forced legislative changes in building codes. Firefighters must prepare and train differently for these new modern building materials. The compliment of irons (for striking and prying) of the future may look entirely different, with the need for a cutting tool for this new, stronger, better window.


Susan Tamme is a 20-year fire service veteran and a captain with Tampa (FL) Fire Rescue (TFR). She is a fire instructor III in the State of Florida and has a M.A. in education. Tamme is also a member of Florida USAR Task Force 3 and the TFR Hazardous Materials Team. She is currently assigned to TFR Ladder and Heavy Rescue unit. Tamme also represents the Southeast Division as a trustee of the International Association of Women in Fire & Emergency Service (iWomen).

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