Impact Windows in Florida

Impact windows are made of two panes bonded to a plastic interlayer, the same idea as a car windshield. Hit one hard enough and it cracks, but it stays in the opening. That is the whole point. A window that blows out lets the storm pressurize the inside of your house, and that is how roofs come off.

Where they are required by code

Florida does not have one rule. It has zones, and which one you are in decides whether this is a choice or not.

• The High Velocity Hurricane Zone. Miami-Dade and Broward counties. The strictest standard in the country. Products here need a Miami-Dade Notice of Acceptance, and opening protection is not optional on a replacement.
• The wind-borne debris region. Defined by design wind speed rather than by county line, which is why it runs through the middle of some counties. If you are in it, replacement glazing has to be protected, either with impact-rated product or with code-approved shutters.
• Everywhere else. Much of inland north and central Florida. Impact glass is not required. Plenty of people install it anyway, for the reasons below.

Because the boundary is drawn by wind speed and distance from open water rather than by county, two houses a few miles apart can fall under different rules. Your county building department is the authority on which side of the line you are on, and a competent installer will already know.

The 25 percent rule catches people

Inside the wind-borne debris region, replacing more than a quarter of your home’s glazed area within a twelve month period generally triggers the protection requirement for that work. Homeowners who plan to do the house a few windows at a time, to spread the cost, sometimes cross that line without realizing it and get a surprise at permitting. Ask about it before you phase a job.

Shutters are a legitimate alternative

Code-approved shutters satisfy opening protection. They cost less up front. The tradeoff is that they only work if somebody is home to put them up, and they do nothing for you the other three hundred and sixty days a year. Impact glass is protection you do not have to deploy, plus it cuts noise and blocks ultraviolet the whole time.

If you travel, if you have a second home here, or if you are getting to an age where putting up panels in August is not realistic, that difference is worth more than the price gap suggests.

What to check on the quote

• The Florida Product Approval number, or the Miami-Dade Notice of Acceptance number in the HVHZ. If a quote will not name the product, you cannot verify anything about it.
• The design pressure rating for your openings, which depends on your wind zone and where the window sits on the wall. A large opening on a corner needs more than a small one in the middle of a wall.
• Whether laminated and impact-rated are being used interchangeably. Laminated glass is not automatically impact rated. The approval number settles it.

Protection is all or nothing

For code and for insurance purposes, opening protection generally means every opening. Doing most of the windows and leaving the sliding door or a bathroom window unprotected can leave you with neither the code compliance nor the insurance credit you were paying for. Decide this at the quote stage, not halfway through.