Impact windows are windows that have been specially designed with higher quality frames, upgraded hardware, and thicker glass -- all of which have been sealed together with some of the strongest adhesives available on the market. The result? A window capable of withstanding not just high wind conditions, but also withstanding high air and water pressure. The following is a quick look at just how much wind and water pressure impact windows can be expected to withstand.
Impact Window Ratings: An Overview and How Much Wind Impact Windows Can Withstand
Impact or hurricane windows use a DP -- design pressure -- rating to identify how much wind they can withstand before bending or braking. What's unique about DP ratings is that they aren't just assigned based on metrics like glass thickness or window size. Instead, a DP rating is only given after a specific model has gone through a barrage of laboratory testing. Furthermore, any model's DP can and often will fluctuate depending upon where it's installed, along with other factors like square footage. For example, the height of your home and its location (coastal vs. inland) and the location of the windows within a home (center of the wall vs. corner of the wall) will alter the window's DP.
To test for the design pressure of a window, the lab will attach the window to a wooden frame that is clamped to a wall specifically designed to simulate real-life building conditions. A machine that simulates wind is then cranked up and the window is tested for the amount of pressure it can withstand before suffering permanent damage. To achieve a given rating, the window must withstand pressure 1.5 times the DP rating for at least ten seconds. Therefore, a window that is rated DP30 has been lab tested to withstand 10 seconds of 45 pounds per square foot of pressure.
In terms of wind speeds, this means a 10 sq ft window located at the center of the wall with a DP30 rating would be capable of withstanding 120-mile wind speeds -- which is roughly a Category 3 hurricane. For those in living in Florida and other coastal communities, it's generally recommended to look for impact windows with a minimum of DP 50, a rating which reflects the ability to withstand most hurricane level 5 wind speeds.
Having impact windows professionally installed further guarantees their ability to withstand both wind and rain. They are one of the most effective ways to protect your family, home, and belongings from the elements.