About High Velocity Hurricane Zone Windows
Explaining What They Are and How They Benefit Your Home
High-Velocity Hurricane Zone (HVHZ) windows are built extra-tough to survive the harshest weather the state of Florida can throw at your home.
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What Are High Velocity Hurricane Zone Windows?
HVHZ windows are windows that have been specially manufactured to withstand the extreme wind, rain, and wind-blown debris caused by Category 5 hurricanes. They’re meant to be installed in homes that are in designated high-velocity hurricane zones—like Miami-Dade County and Broward County.
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Get Impact Resistance AND Energy Efficiency
HVHZ-rated windows can help enhance your home’s energy efficiency. Adjust the slider below to match your monthly energy bill to get an estimate of your potential annual energy savings*:
Based on figures determined by ENERGY STAR when upgrading from a single-pane ‘clear’ window to an ENERGY STAR-compliant window at an average 12% energy consumption reduction.
About HVHZ Certification for Windows
Fatigue Load Testing
Windows need to pass fatigue load testing at three intensity levels: up to 0.5p 600 times, up to 0.6p 70 times, and up to 1.3p once for three seconds.
Large Missile Impact Testing
Windows need to pass Missile Impact D testing, where a 9-pound 2×4 is fired at the window at a speed of 50 feet per second (34 mph).
Small Missile Impact Testing
Windows are also tested for repeated impacts from small objects. 30 steel balls weighing 2 grams are fired at 130 feet per second (88 mph).
Cyclic Wind Pressure Loading (Inward)
Windows need to stand up to inward-acting wind pressure for thousands of cycles at different intensities.
Cyclic Wind Pressure Loading (Outward)
Windows also need to pass outward-acting wind pressures between 0.5p to 1.0p for thousands of cycles.
Sustained Wind Pressure Resistance
HVHZ windows need to be able to take sustained wind gusts (lasting 3+ seconds) of 170-175 miles per hour.
The Best High Velocity Hurricane Zone Brands
Karoly Windows partners with the best window makers in Florida to source HVHZ-compliant windows (and doors) for homeowners throughout the greater Tampa Bay area. We’re selective about the brands we work with so we can ensure that you’re getting the best windows for your home.
Simonton and PGT are two of the top brands we work with for impact windows, providing extensively tested impact windows that meet or exceed the requirements of Miami-Dade and Broward County.
Types of HVHZ Windows
Impact Windows
Double Hung Windows
Sliding Windows
Picture Windows
Casement Windows
Awning Windows
Bay Windows
Custom Windows
Protect Your Home Sooner with HVHZ Window Financing
Need to protect your home as soon as possible, but also need to reduce the impact on your wallet? Consider using window financing to cover the cost of installing your high velocity hurricane zone windows.
Karoly Windows partners with GreenSky and Synchrony Financial to provide you with flexible financing options for your window installation, including offers with no down payment, 0% introductory interest, and no payments required for 12 months! Pay off your windows before the introductory period ends, and you won’t have to pay a dime of interest!
We also offer longer-term financing options for those who need to spread out their payments more to fit in their household budget. Get your new windows faster by taking advantage of flexible financing with Karoly Windows & Doors!
0% Interest Financing Options
Two great plans — see which one fits your budget best.
GreenSky 12-Month Plan
- No payments required for 12 months
- Pay it off within 12 months = 0% interest
- $0 Down Payment
- If paying after 12 months → fixed payments over 84 months
Synchrony 24-Month Plan
- Lower monthly payments starting right away
- Pay it off within 24 months = 0% interest
- $0 Down Payment
- Minimum payment ≈ 3% of balance each month
See Your Actual Monthly Numbers
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High-Velocity Hurricane Zone Doors
In addition to your windows, it’s important to have your doors be as strong as possible to resist hurricane impacts. HVHZ doors are built to withstand massive blows from flying storm debris and constant pressure from high winds to better protect your home against hurricane season and other threats.
HVHZ Door Options in Florida
Sliding Glass Doors
Standard Sliding Patio Doors
Pocket Sliding Doors
Bi-Parting Doors
Exterior Doors
Entry Doors
Double Entry Doors
French Doors
What Kinds of Impacts Can an HVHZ Door Take?
Every HVHZ-certified door is built to withstand extreme impacts, but just how hard an impact can an HVHZ door take? That actually depends on the door. Every HVHZ-rated door has to pass the Small and Large Missile Impact D testing standards and be able to withstand wind loads of 175 mph (the minimum requirement for risk category II buildings per FBC guidelines).
The large missile impact test fires a 2 x 4 weighing nine pounds to simulate the impact of flying debris against the door. But, how much more can the door take beyond the minimum required to pass the test? The answer depends on the specific door and how well it’s installed.
A well-made door with a high design pressure rating and impact-resistant materials may be able to take significantly more impact than a non-impact door of similar size and install quality. On the other hand, things like how securely the door is mounted to the frame, how deep the fastenings penetrate the opening around the frame, and the quality of the door’s locking mechanisms can also have a significant impact on how well the door stands up to repeated hits during a storm.
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High Velocity Hurricane Zone Window FAQs
What Is the High Velocity Hurricane Zone Rating?
The short answer is that it’s a set of building codes for Florida homes that applies to Miami-Dade and Broward County. The Florida Building Code (FBC) applies more stringent structural integrity requirements on buildings in these areas because they have a high risk of encountering category 5 hurricane conditions.
However, these two counties aren’t the only areas of Florida that may be exposed to Category 5 hurricane risks. Frequently, seasonal hurricanes work their way up the Gulf to make landfall along the west coast of Florida, which poses a severe wind and debris impact hazard to homes throughout the greater Tampa Bay area.
Are HVHZ Windows the Same as Impact Windows?
No. Although the two terms are closely related, HVHZ-rated and impact-rated aren’t the same thing.
The difference is that HVHZ windows are specifically designed and certified to withstand category 5 hurricane conditions per Miami-Dade and Broward County standards. Meanwhile, impact windows are rated to resist impacts, but aren’t guaranteed to meet HVHZ requirements.
All HVHZ windows are impact-rated, but not all impact windows are HVHZ-rated. Sort of like how all semi-trucks are motor vehicles, but not all motor vehicles are semi-trucks.
What’s the Highest Category Rating for a Hurricane?
On the Saffir-Simpson hurricane wind scale, the highest hurricane category rating is category 5. This means that the hurricane has 157 mph or higher sustained winds—making them the most destructive hurricanes. Category 5 storms frequently cause catastrophic damage to homes over a large area.
Insufficiently-protected homes will be destroyed if subjected to a category 5 hurricane. The simple formula for wind pressure is P = 0.00256 x V2, where P is pressure in pounds per square foot and V is wind speed in miles per hour.
A wind speed of 157 miles per hour will exert 63.1 pounds per square foot of force. If you have a window that is four square feet in area, that means it will be subjected to 252.4 pounds of force consistently throughout a Cat 5 hurricane—more than the average weight of an adult male (according to Healthline, the average 30-39 year old man weighs an average of 208.1 pounds).
This doesn’t account for the damage that can be caused when such high-speed winds pick up debris and throw it at your home.
With a properly-installed HVHZ window, you can limit one of the largest vulnerabilities in your home to minimize the risk of catastrophic damage from hurricanes.
Can a Single Broken Window Really Cause Total Structural Collapse?
Yes. A window breaking during a major hurricane where your home is being subjected to extreme wind pressure can cause catastrophic, cascading damage to your home. Think of it like dominoes: once the first domino is knocked over, the rest of the dominoes in the chain will soon follow suit.
When a window breaks during a hurricane, the wind rushes into the opening, causing a sudden and massive shift in pressure, pushing up against the internal walls of your home that aren’t meant to handle the wind load. It also results in wind pressure pushing against the underside of your roof, which can result in the roof tearing free much more easily than it would if the envelope of the home remained intact.
Since windows are the proverbial weakest link in the chain of your home’s hurricane protection, replacing your existing windows with HVHZ-rated windows is the best way to maximize your home’s protection against hurricane-force winds.
What Is “Category 5 Hurricane Proof?”
A “hurricane-proof” structure is one that is built to withstand winds in excess of the wind speed of the most powerful hurricane ever recorded.
As of the time of this writing, the strongest hurricane on record is, according to The Weather Channel, Hurricane Patricia, which had sustained winds of 215 mph. Buildings that can survive sustained 245+ mph winds are currently considered “hurricane-proof.”
However, that’s only hurricane-proof against the winds from the strongest currently-known hurricanes. That does not indicate absolute resistance to other natural hazards that may occur during hurricanes, such as flying debris impacts, water damage, or localized tornadoes.
What Are the Negatives of HVHZ Windows in Florida?
The biggest thing that prevents most homeowners from using high velocity hurricane zone impact windows over less durable windows is the cost. The upfront cost of installing HVHZ windows and doors is typically higher than the cost for non-impact windows because they cost more to make and require more careful installation to make the most of their impact resistance.
However, using HVHZ windows and doors can provide a long-term savings that more than makes up for the price difference.
Think of it this way: Which is more expensive?
Installing an HVHZ window once, or doing all of the following:
- Paying for a second window replacement
- Repairing damaged flooring
- Replacing damaged furniture
- Paying for increased homeowner’s insurance premiums
- Having to rent a room while water/storm damage remediation work is being done
- Paying for storage for undamaged furniture and belongings while remediation crews work
- Paying for storm damage remediation work
This doesn’t even take into account the possibility of total structural collapse that a broken window can create during a major hurricane. The cost of storm damage after a window breaks can easily exceed tens of thousands of dollars of damage.
Are High Velocity Hurricane Zone Windows Really Hurricane-Proof?
They’re incredibly resistant to hurricane-force winds and impacts, but they aren’t absolutely hurricane-proof. A hurricane that’s strong enough can put out winds that will topple almost any building, spawn tornadoes that do massive localized damage, and pick up and throw cars.
An HVHZ window can take a lot of punishment and will have “fail states” taken into account with multiple panes of glass, flexible laminate layers, and strong frames to keep protecting the home even after the first layer of glass is broken, but no window will be 100% resistant to all potential super-storms.
That said, HVHZ windows provide a significant improvement over other windows for your home’s hurricane survivability. You’re much less likely to have water or debris intrusion into the home with high velocity hurricane-resistant windows and doors than you are with non-HVHZ windows and doors.
Can HVHZ Windows Help Reduce My Insurance Costs?
Yes! Installing HVHZ windows and other weatherproofing features can help you reduce the cost of home insurance in the state of Florida.
This is because insurance companies have to consider risk when making insurance quotes. Florida is considered a high risk area for hurricane impacts, which drives up home insurance costs in the state. Taking measures against hurricanes and their effects can reduce your risk profile, leading to potential savings on insurance costs.
As noted by Oyer Insurance, “Installing impact-resistant windows can protect your home from wind damage during hurricanes. This upgrade can make you eligible for discounts from many insurers.” With insurance costs being in the thousands per year for many homes, an HVHZ window upgrade can be a major long-term cost savings that pays for itself in time.
The Best HVHZ Window Installers in Florida
Karoly Windows & Doors is a Tampa Bay Times Best of the Best Winner (2023, 2024 & 2025) and has earned the National Best of the Best award every year since 2018, thanks to our:
Best-in-Class Service. Where many contractors cut corners to get the job done as cheaply as possible, we’re dedicated to going the extra mile to ensure that every install job is done perfectly.
Proactive Communication. We believe in building trust by being transparent and open to keep you informed from start to finish. Stay in the know so you’re never in the dark.
Consistent Quality. On every project, we tailor each detail until it meets the highest standards and expectations so you’re 100% satisfied. We never cut corners and we use in-house installation technicians to ensure our standards are upheld.
Best Price Guarantee. We’re confident that you won’t find a better deal elsewhere. We provide the best quality and will price match comparable window installation project quotes.
Lifetime Labor & Extensive Warranties. Our work is covered by a 25-year installation warranty and a 50-year material warranty so you can have peace of mind.
We go the extra mile for homeowners so you can rest easy knowing that your home is protected as much as possible with top-quality HVHZ window installation work.
Areas We Serve
Are you looking to install a high velocity hurricane zone-rated window for your Florida home? Karoly can help! We provide HVHZ-certified window replacement services in:
Hurricane Window Protection Installation & Other Videos
Learn more about impact-resistant HVHZ-rated windows and other topics related to window and door installation by subscribing to the Karoly Windows YouTube channel! Here’s a quick example of a video you can find on our YouTube channel:
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