Impact-Resistant Windows: What You Need To Know

Tue Oct 22 2019

If you live in South Florida or other hurricane-prone areas of the country, you will likely benefit from impact-resistant windows on your home.

In this guide, we’ll offer an overview of what impact-resistant windows are, how to determine whether you home needs them, how to determine whether your home already has them, and what to expect in terms of cost.

Impact-Resistant Glass Requirements

Impact-resistant windows (also sometimes called impact windows, hurricane windows, or laminated glass) are windows specifically designed to withstand the stresses of hurricanes, including high winds and projectiles moving at high speeds.

Structurally, impact-resistant windows are made of:

  • Two panes of shatter-resistant glass. If the exterior glass is shattered by a projectile, the inner layer remains, protecting the house. Because of the way the glass is designed, it doesn’t break into dangerous shards.
  • An adhesive layer holding the panes together. This might be PVB, EVA, or resin. It’s the same substance used in car windows to prevent shattering.
  • A strong frame. Frames may be either metal (typically steel or aluminum), vinyl, or wood. Metal frames are the strongest and most expensive; wood frames are the least expensive to install, but require more maintenance.

But not every double-paned window is considered impact resistant. In fact, to get the official “impact resistant” designation from American Society for Testing and Materials (ASTM), windows must pass a series of rigorous tests.

Impact resistance testing involves:

  • Large missile impact: For South Florida homes, this test involves hurling a nine-pound wooden two-by-four at the window at 80 feet per second, first at the center of the pane and then at its edges. To pass, the glass must not shatter at either impact. (For homes outside South Florida, the missiles are lobbed at slower speeds.)
  • Small missile impact: In this test, bits of gravel or steel ball bearings are lobbed at the glass at 80 feet per second.
  • Wind simulation: In this portion, testers simulate wind speeds of up to 200 miles per hour. To pass, the window has to maintain structural integrity.

Assuming a window passes these tests, it’s certified as impact resistant. But how do you know if your house needs these specialty windows? The biggest factor is where you live.

Who Needs Impact Resistant Windows?

While anyone worried about storm damage can install impact-resistant windows, people in Florida’s most hurricane-prone regions can benefit most.

Each region of the state of Florida has a designated hurricane-evacuation code, identified by a letter of the alphabet. Those in zones closer to the start of the alphabet (A, B, C) are most vulnerable to hurricane damage, including storm surges, high winds, and loose debris. These are also the people who benefit most from impact-resistant windows.

(Not sure which zone you’re in? Enter your address here to check.)

Impact-resistant windows protect those in the path of a hurricane in three important ways:

  1. They don’t break into shards, which means they prevent glass shards from flying through the air and causing injury or property damage.
  2. Their double-pane structure means that even if the outer pane shatters, the inner pane prevents water from damaging the home.
  3. By keeping your home sealed, these windows prevent hurricane winds from getting inside and significantly raising the air pressure inside your home, which can lead to the collapse of walls and roofs.

That last form of protection is actually the most important one. Structure collapse from changed air pressure is much more devastating and expensive than damage caused by water getting onto your stuff.

Not a homeowner in Florida’s top hurricane-evacuation zones? You may still benefit from impact-resistant windows if you’re looking for a way to protect your home from UV damage (hurricane windows also block most UV rays) or to dampen sound (impact windows are great at reducing sound).

If you do need impact-resistant windows, you’ll probably have to have a hurricane protection company install them for you.

How Can You Tell if You Already Have Impact-Resistant Windows?

If you’re not sure whether the windows in your home are impact resistant, a visual inspection should give you the information you need. Follow these steps:

  1. Look in the corner of the pane. Often, suppliers mark their glass with their name, the date the glass was manufactured, and technical specifications about what the window can withstand. If there’s no mark etched into the glass, there may be a stick-on notice with the same information.
  2. Check your reflection. Because impact-resistant windows are made up of two panes of glass, they’ll show two reflections (instead of the single reflection a normal window will show). For best results, wait until it’s dark out to try this.
  3. Check the deed to your house. As of July 2001, all homes built in South Florida are required to have impact-resistant windows. If you’re not sure when your home was built, check your deed, which will show all past owners and their years of ownership. If the dates go back no further than 2001, there’s a good chance your windows are impact-resistant (assuming you’re in South Florida).

So if you don’t have impact-resistant hurricane windows and you likely need them based on your hurricane evacuation zone, what should you do? Read on to understand the cost of installing impact-resistant windows, plus a few alternatives for those on a tight budget.

How Much Do Impact-Resistant Windows Cost?

Impact-resistant windows cost more than standard windows. But they can also protect you from serious damage and may qualify you for lower homeowners insurance premiums (ask your insurance company for details).

While impact-resistant windows with hurricane shutters are the gold standard for homes in South Florida and other areas affected by hurricanes, they are not the only way to mitigate your risk of hurricane damage. Here’s a look at how impact-resistant windows and some alternatives stack up.

Solution Cost Installation? Reduces premium?
Impact-resistant windows $40 - $55/sq ft. Professional Yes
Hurricane shutters $10 – $50/sq. ft. Homeowner No
Hurricane-resistant film $25/sq. ft. Professional No
Plywood $5 - $6 /sq. ft.  Homeowner No

If a hurricane is on the way and you don’t have time to install impact-resistant windows, it’s better to do something (e.g., cover your windows with plywood) than nothing. But for superior long-term protection, impact-resistant windows can’t be beat.

In new construction, opting for impact-resistant windows will only raise the cost of the home by a few thousand dollars. It’s possible that you’d recover this savings within a few years of reduced homeowners insurance premiums.

For existing homes, the potential to recover your investment via smaller insurance premiums is also significant.

In other words, a small investment today can save you money over and over in the years to come.

Other Ways to Protect Your Home from Hurricanes

![windows-6]( =300x)Hurricanes are one of the most destructive forces of nature. If you live in South Florida or another hurricane-prone area, you’ll want to do more than verify that you’ve got impact-resistant windows. Other ways to protect your home from a hurricane include these:

  • Update your roof per wind mitigation guidelines. Certain types of roof construction can both reduce your risk of wind damage and lower your homeowners insurance premiums.
  • Verify that you have flood insurance. Flood insurance is not included in standard homeowners policies. If you’re in a hurricane danger zone, be sure you purchase this coverage separately.
  • Maintain your home consistently. Regular home maintenance can prevent small problems from becoming big ones. Cleaning your gutters, for example, can ensure that water runs through them rather than getting clogged and leaking into your attic.

Still not sure whether you have or need impact-resistant windows? Get in touch with us, and we’ll help you figure it out.