FAQs
Installers, dealers, builders and homeowners should know that the proper installation of impact-resistant windows—following the detailed steps—are essential to assuring optimum performance of these very special windows.

The answers to these frequently asked questions explain:

Q: What are impact-resistant windows designed to do?

A: Impact-resistant windows are designed to prevent penetration of windborne debris that strikes the window during seasonal high-wind events, as well as to withstand high-wind pressure. To be effective, the window must withstand flying projectiles striking the glass.

When installed correctly, impact-resistant windows help keep a home’s building envelope intact. When combined with other structural reinforcements specified by local building codes, the windows can help keep high winds from tearing the house apart from the inside out.

Q: What is done differently during the installation of the windows that keeps them in place?

A: For impact-resistant windows to function properly they must stay anchored to the substrate to which they are attached. To accomplish this, additional screws are used to secure the window, and those screws must have deeper penetration into the substrate.

For example, a 3-by-5 standard window may require 13 screws be driven into the wooden substrate, the material that anchors the windows to the house. The screws are drilled through pre-made holes in the window, through the exterior of the house and into the substrate at a depth of one-half inch. A comparable impact-resistant window could potentially require 18 or more screws specified for its installation. Those screws are going to be longer, as they will have to penetrate the substrate more deeply—usually by a minimum of 1 1/2 inches. The diameter of the screws might also be increased to help secure the window.

Minimum standards covering the screw type, size, material and length are set depending on the required embedment into the substrate, which can be concrete form, concrete block, wood frame or steel stud.
Always check with either the product manufacturer or a product approval Web site for specific product anchoring and installation instructions.

Q: How are the code requirements determined?

A: State and local agencies responsible for building codes mandate what the minimum requirements are for installation in their respective areas. Manufacturers are then responsible for developing installation (anchorage) instructions for their specific products that adhere to these codes. We have very high standards in Florida and some of the strictest requirements for installation of impact-resistant windows in high-wind zones (typically 120 mph wind speed or greater) of anywhere in the nation.

A project’s specifier—be it an architect, engineer or the homebuilder—passes on to us the required installation specifications for their projects. The requirements they provide may be the same as those mandated by the building codes, or they could recommend more stringent specs based on the location of the building, the building’s height and how much exposure it could have to high winds. Industry professionals can choose to make the specifications stronger than the codes in their areas, but they can’t make them any weaker.

Based on the provided requirements, we have a certified engineer determine placement of screws that will best enable the window to meet the specifications provided, withstand a debris strike and remain anchored to the substrate. We affix the requirement information to each window so that it is very obvious to installers.

Q: Are the materials used to secure a window to the structure different than those for traditional windows?

A: Specifications may or may not call for screws made from a non-corrosive material, such as stainless steel. In coastal areas of Florida, we deal with rust and corrosion on a daily basis. The fact that certain screws won’t break down over time adds extra assurance that a window will remain anchored during a high-wind event. In Florida, non-corrosive screws, although more expensive than standard screws, are easy to come by. We remind our customers this is an easy, yet important, upgrade. It’s well worth paying the additional cost to add to the integrity of the building envelope.

Q: How is the installation of impact-resistant windows certified?

A: In Florida, inspectors come out and verify that windows are installed properly. As requirements specified by the manufacturer are affixed to each window prior to shipment, they’re plainly visible during installation and inspection.

In their review of a building, inspectors are completely within their rights to go to every window, if they choose, and remove screws to verify that the length of the screw and the depth of its penetration into the substrate meet the provided specs. If they find even one screw that does not meet the stated specifications, they’ll “red tag” the entire project. This means the project didn’t pass inspection, and the job is shut down until all of the failures the inspector found are brought up to code.

Q: Do you see the Florida code requirements being adopted elsewhere? What effects might result from such a change?

A: What’s exciting about the change is that it gives us the opportunity to take the lead in specifying and marketing what we feel is a better and safer window across hurricane prone regions. We’re passionate about the change in code because we feel it will make a positive impact on the state and even save lives in the event of a natural disaster or extreme weather event. In addition, installation instructions from the manufacturer are now required by the International Residential and Building codes and as the later versions are adopted by state and local code bodies these installation and anchoring details will become mandatory.

Hopefully, increasing the size of the impact-resistant window market – not just across Florida, but across the nation – will help drive down the cost of these products. Right now, impact-resistant windows really are a niche market due to their higher cost, and the average consumer finds it difficult to afford the product. Tightening up the building code will expand the market and enable volume production of the windows, which will make them significantly more affordable and bring added peace-of-mind to homeowners as they’ll know they have an extra level of protection in the event of extreme weather.

Randy Hile is vice president of operations for windows for the Florida division of Atrium Companies, Inc.,
www.atrium.com.