What Are Hurricane-Rated Windows?
Hurricane impact windows are typically manufactured with glass that’s specially treated to make it less likely to shatter and break loose from the window frame during a violent windstorm. Although the glass may still shatter when struck by airborne objects propelled by powerful winds, an impact-resistant window is designed to remain intact so that pieces of glass don’t become dangerous missiles inside the home and the risk of damage from heavy rain and wind is minimized.
There are a number of ways that impact-resistant windows are rated, but one of the most common incorporates the Saffir-Simpson Hurricane Wind Scale that is used to classify hurricane strength according to wind speed. Here’s what that breakdown looks like:
- Category 1 – With 75 to 95 mph winds, the power of this storm is likely to damage roofs, gutters, trees, utility poles, and power lines.
- Category 2 – Described by the National Hurricane Center as extremely dangerous with winds of 96 to 110 mph, a storm in this category is capable of causing extensive damage, even to well-built homes.
- Category 3 – With winds of 111 to 129 mph, this category of hurricane is capable of inflicting devastating residential damage.
- Category 4 – Considered capable of causing catastrophic damage, storms in this category have sustained winds of 130 to 156 mph.
- Category 5 – A storm with winds of 157 mph or higher is likely to cause catastrophic damage to a high percentage of homes in the affected area.
High-Speed Winds Create Hurricane Force
A window’s ability to withstand high-speed winds is typically expressed as how many pounds of pressure the window can take without breaking—a measurement that’s called “design pressure,” aka DP. Although the higher the DP rating, the more wind speed the window can handle, there are variables such as window size and whether the window is in the center of an exterior wall or located near a corner. Therefore, an impact window that’s rated to withstand a Category 5 hurricane is likely to have a DP-45 score or higher, but a DP-45 rating may not necessarily mean the window will stand up to a Category 5 hurricane in every situation.
Homeowners who are shopping for hurricane windows may also encounter another rating: the performance grade (PG). This is an overall rating for how well the window performs under the pressure created by hurricane-force windows. This rating encompasses scores for three metrics: whether the window remains structurally sound, and how well it prevents air and water infiltration.
However, wind pressure is not the only force a window is likely to face during a hurricane. Uprooted trees, snapped branches, dislodged roof materials, and other wind-propelled items often become missiles that smash through windows, allowing wind and rain to enter the home and wreak havoc. Therefore, it’s important to measure a hurricane window’s resistance to breaking when struck by wind-propelled debris.
How Are Hurricane-Rated Windows Tested?
Hurricane windows are tested according to standards set by the American Society for Testing & Materials (ASTM) and government building codes in various hurricane-prone regions. For DP ratings, windows undergo testing to determine how much physical force they can withstand without giving way, and they’ll also receive a score for how well they prevent air and water infiltration when subjected to hurricane-force winds.
Then there’s the missile test. Typically, a window that’s certified for impact resistance must pass a series of tests that include striking it with 9-pound 2-by-4s propelled at various wind speeds.
An Easier Way to Look for High-Performing Hurricane Windows
If you’re in the market for impact-resistant replacement windows for your home, an easier way to gauge their likely performance is to ask whether they meet Florida Building Code standards for high-velocity hurricane zones. Thanks to the ongoing threat of hurricanes, Florida has adopted high standards for hurricane windows that can protect homes from damage and help homeowners potentially lower their insurance costs.
If you’re a Florida homeowner on the hunt for hurricane-rated windows, you can feel confident turning to NewSouth Window Solutions. We proudly manufacture and install beautiful replacement windows designed to meet the needs of Florida homeowners, including storm protection. Contact us today, and we’ll be happy to discuss the outstanding features and ratings that make our windows an excellent choice for your home.