Hurricane Window Ratings Explained
What "hurricane-rated" actually means on a Florida window or door: design pressure, missile impact, HVHZ approval, and the label and approval documents that prove it.
The short answer
A hurricane window rating is not a single grade. In Florida, a window or door counts as hurricane-rated when a product approval documents, for the exact configuration you install:
- Design pressure: the positive (inward) and negative (outward) wind load in pounds per square foot the unit resisted in testing.
- Impact resistance: a large missile or small missile test, followed by thousands of pressure cycles on the damaged unit.
- Where it is approved: a Miami-Dade Notice of Acceptance (NOA) or a Florida Product Approval (FL number), and whether that approval covers the High-Velocity Hurricane Zone.
- Limits: maximum size, glass makeup, frame, hardware, and anchoring. Outside those limits, the rating does not apply.
The rating is only half of the match. The other half is what your opening needs: the pressures from a wind load calculation and the impact protection your county requires. A window is the right one when its approved ratings meet or exceed both.
Quick reference: every rating on a hurricane window
Each line below appears on a product approval, and most appear on the label. The last column is the question to ask for your house.
| Rating | What it measures | How it is tested | Compare it to |
|---|---|---|---|
| Design pressure (DP) | Uniform wind load the unit resists, inward (+) and outward (−), in psf | Uniform static air pressure: TAS 202 in the HVHZ, ASTM E330 elsewhere | The required + and − pressures for that opening, from the wind load calculation |
| Large missile impact | Resistance to heavy debris such as lumber | 9 lb 2x4 timber at 50 ft/s: TAS 201, or ASTM E1886 with E1996 missile D | Required for glazed openings up to 30 ft above grade, which covers a typical house |
| Small missile impact | Resistance to roof gravel and other small debris | 2-gram steel balls at 130 ft/s: TAS 201, or ASTM E1886 with E1996 missile A | Applies to openings more than 30 ft above grade; not enough for a ground-floor opening |
| Cyclic pressure (after impact) | Whether the damaged unit stays closed through thousands of gust cycles | TAS 203 in the HVHZ (4,500 inward + 4,500 outward cycles); ASTM E1886 elsewhere | Part of the impact rating. A unit is not impact-rated without it |
| Water infiltration | Wind-driven rain resistance at a test pressure tied to the DP | Water spray at a fraction of the design pressure (TAS 202, ASTM E547 / E331) | Look for it on the approval or in the Performance Grade; it is a leak test, not a flood rating |
| Approval and jurisdiction | Where the tested configuration may legally be installed | Miami-Dade NOA, or Florida Product Approval (FL number) with HVHZ yes/no | Your county: Miami-Dade and Broward need HVHZ-valid approval |
There is no "Category 5 window"
Many window ads match products to hurricane categories. The code does not. Saffir-Simpson categories classify a storm by its one-minute sustained wind. The Florida Building Code, through ASCE 7, uses a mapped design wind speed: a three-second gust at 33 feet above open ground. For a house, that speed is 175 mph in Miami-Dade and 170 mph in Broward, and 160 to 170 mph in Palm Beach depending on location (see the Florida wind zone map).
Engineers convert that speed into a pressure for each opening. A window is then rated by the pressure it resisted and the impact test it passed. The same window can be more than enough for a small inland opening and too weak for a large corner slider on the bay. That is why a storm category, or a wind speed alone, cannot tell you whether a window is right for an opening.
1. Design pressure: the wind load rating
Design pressure (DP) is the uniform wind load, in psf, a window or door resisted in a pressure chamber. Approvals list it as two numbers: positive for wind pushing in and negative for suction pulling out. On a house the negative value usually controls, especially near corners. Testing goes past the rating: the North American Fenestration Standard applies a structural test pressure of 150 percent of DP for windows and doors.
The number you compare it to comes from ASCE 7 wind loads. The design wind speed becomes a velocity pressure at the roof height, then coefficients for the wall zone and the size of the opening produce a positive and a negative pressure. That result is multiplied by 0.6, because product ratings are allowable (ASD) values. The wind load calculator runs that chain for a South Florida house for planning, and the wind speed to psf calculator shows the speed-to-pressure step by itself.
- The product's positive DP must meet or exceed the opening's positive pressure, and its negative DP must meet or exceed the opening's negative pressure.
- Ratings often change with size. An approval can list a lower DP for a larger unit of the same model, so check the line for your width and height.
- Mullions, glass type, and anchors can each limit the rating. The lowest limit in the assembly governs.
For DP labels like +50/−60, how the test works, and typical South Florida ranges, read the design pressure ratings deep dive.
2. Impact resistance: large missile vs small missile
An impact rating says the unit kept the opening closed after being hit by wind-borne debris and then cycled with wind pressure. Laminated impact glass is expected to crack in the test. It passes when the interlayer and frame hold, the missile does not penetrate, and the damaged unit survives the pressure cycles.
Large missile
A nominal 2x4 timber weighing 9 pounds, fired from an air cannon at 50 feet per second. In the HVHZ, each of three specimens takes two hits (center and corner) under TAS 201. Under ASTM E1996 this is missile level D. Essential facilities such as hospitals use a faster 80 feet per second shot for openings up to 30 feet.
Small missile
Solid 2-gram steel balls at 130 feet per second, standing in for roof gravel. The HVHZ test delivers 30 impacts per specimen in groups of 10. Under ASTM E1996 this is missile level A.
Which one applies. In the HVHZ, Section 1626 of the Florida Building Code requires the large missile test for assemblies up to and including 30 feet above grade and the small missile test above 30 feet. Outside the HVHZ, ASTM E1996 picks the missile by wind zone, height, and protection level. At South Florida's design wind speeds, the E1996 table also points to missile D, the 9-pound 2x4, for openings within 30 feet of grade. In practice, every window and door on a typical house needs a large missile rating. Hospitals, fire stations and other Risk Category IV essential facilities use the large missile at every height; the building risk category guide explains how those categories are assigned.
Then the cycling. After impact, the specimens go through pressure cycles. In the HVHZ, TAS 203 and Table 1626 call for 4,500 inward and 4,500 outward cycles at stepped fractions of the maximum test pressure. Outside the HVHZ, ASTM E1886 runs the cyclic sequence that ASTM E1996 specifies. An impact rating includes this step. A unit that only survived the hit is not impact-rated.
3. HVHZ, wind zones, and where a rating counts
The High-Velocity Hurricane Zone (HVHZ) is Miami-Dade County and Broward County. Products there must be tested to Miami-Dade's protocols: TAS 201 for impact, TAS 202 for uniform static air pressure (plus air and water infiltration), and TAS 203 for cyclic pressure. The approval must be valid for HVHZ use.
Palm Beach County is outside the HVHZ but inside the wind-borne debris region, so glazed openings still need impact-resistant products or approved shutters. There, a Florida Product Approval tested to ASTM E1886 and E1996 is the usual path, and an NOA is also accepted.
| County | Design wind speed (house) | HVHZ | Usual test standards | Approval accepted |
|---|---|---|---|---|
| Miami-Dade | 175 mph | Yes | TAS 201, TAS 202, TAS 203 | Miami-Dade NOA, or a Florida Product Approval approved for use in the HVHZ |
| Broward | 170 mph | Yes | TAS 201, TAS 202, TAS 203 | Miami-Dade NOA, or a Florida Product Approval approved for use in the HVHZ |
| Palm Beach | 160 to 170 mph, by location | No | ASTM E1886 / E1996 (TAS also accepted) | Florida Product Approval or Miami-Dade NOA |
Risk Category II speeds from the shared county table used by the wind load calculator and the wind zone map. A product approved for HVHZ use also meets the debris-region rules outside the HVHZ. A statewide approval without the HVHZ designation is not enough in Miami-Dade or Broward. The Florida Building Code guide covers the permit path.
4. Miami-Dade NOA vs Florida Product Approval
Miami-Dade NOA
A Notice of Acceptance is Miami-Dade County's approval of a specific product after review of HVHZ test reports and drawings. It is a PDF with the product description, size limits, design pressures, glass and anchoring details, and an expiration date. It is accepted throughout Florida.
Look it up on the Miami-Dade Product Control search by manufacturer, category, or NOA number.
Florida Product Approval
The statewide approval issued through the Florida Building Commission, identified by an FL number with a suffix for each product. Each listing shows whether it is approved for use in the HVHZ, whether it is impact resistant, its design pressure, and its installation instructions.
Look it up on the Florida Building Code Online product approval search by FL number or manufacturer.
Ask your contractor for the approval number of every product in the quote, then open the document yourself. A brochure or a sticker is not the approval. This site never lists approval numbers for you: use the manufacturer's current document for the model you are buying.
5. Water infiltration and the other label items
- Water infiltration. Water is sprayed on the unit while air pressure is applied. TAS 202 runs it at no less than 15 percent of the positive design pressure. Under the North American Fenestration Standard, the water test pressure is generally 15 percent of DP (20 percent for the heavy-commercial AW class), with a minimum and a cap. It measures resistance to wind-driven rain, not flooding.
- Performance Grade (PG). A NAFS rating such as "PG50." It is limited by the weakest of the structural, water, and air results, so a unit's PG can be lower than its structural DP. In Florida, the approval's design pressure is what the permit checks.
- Performance Class. R, LC, CW, or AW in NAFS, from residential to architectural. R is the class commonly used for one- and two-family homes.
- Air infiltration and forced entry. TAS 202 also measures air leakage and includes a forced-entry test. They matter for comfort and security, not for the hurricane rating itself.
- Energy label. An NFRC label shows U-factor and solar heat gain. It is an energy rating, not a hurricane rating.
How to read a product label and approval
- Find the permanent label. NOA products carry a permanent label with the manufacturer's name and the statement "Miami-Dade County Product Control Approved," and units under a Florida approval are labeled as that approval requires. Temporary stickers from the factory often show the model, DP, impact rating, and approval number, and are usually removed after final inspection, so photograph them first.
- Do not stop at the glass etching. A mark in the corner of the glass usually identifies the glass or laminate maker. It does not prove the whole window, frame, and anchoring are approved.
- Get the approval number. NOA number or FL number, from the label, the quote, or the permit file.
- Open the approval and check it is current. NOAs show an expiration date. Florida approvals show their status and the code edition.
- Match the configuration. Model, width and height, glass makeup, frame material, and anchors must fall inside the approval. Note the design pressure for that size.
- Check the impact line. Large missile for a house. For Miami-Dade and Broward, confirm the approval is valid for HVHZ use.
- Compare to the opening. The approved positive and negative DP must meet or exceed the pressures for that opening from the wind load calculation.
Homeowner checklist before you buy
- I know my county's design wind speed and whether I am in the HVHZ (wind zone map).
- I have planning pressures for each opening (wind load calculator), and the permit will use sealed or county-accepted values.
- Every product in the quote has an NOA or FL number I have opened and checked is current.
- Each approval covers my sizes, and its + and − DP at those sizes meet my pressures, including corner openings.
- Every glazed opening on the house has a large missile impact rating, or an approved shutter.
- In Miami-Dade or Broward, each approval is valid for HVHZ use.
- Installation will follow the approval's anchoring, and I will keep the approvals and permit records for insurance.
Shopping by product type? Compare frames and operation styles in the impact windows guide and the impact doors guide. For what documented opening protection can mean for premiums, see insurance savings.
Hurricane window rating questions
What is a hurricane window rating?
It is not one number. In Florida a window or door is hurricane-rated when it holds a product approval showing three things for the exact configuration installed: a design pressure in psf for inward and outward wind load, an impact rating from a large or small missile test followed by cyclic pressure, and where the approval is valid, including whether it covers the High-Velocity Hurricane Zone. The approval also limits size, glass, frame, anchors, and hardware.
Is there a Category 5 hurricane window?
Not as a code rating. Saffir-Simpson categories describe a storm by its one-minute sustained wind. The Florida Building Code designs buildings with mapped design wind speeds, which are three-second gusts, and turns them into pressures for each opening. Windows are rated by design pressure and impact test, not by storm category. A marketing claim that a window is rated for a hurricane category does not replace the approval.
What design pressure do I need in Miami-Dade or Broward?
There is no single county number. The required pressure depends on design wind speed, mean roof height, wind exposure, opening size, and whether the opening sits near a corner. Each opening gets its own positive and negative value. The wind load calculator on this site estimates them for planning. The permit uses pressures from a calculation sealed by a Florida-licensed Professional Engineer, or a county method the building department accepts.
Large missile or small missile: which one does a house need?
Large missile for the windows and doors of a typical house. The Florida Building Code applies the large missile test to openings up to and including 30 feet above grade, and the small missile test above 30 feet. Risk Category IV essential facilities use the large missile at every height. A product that passed only the small missile test is meant for upper floors of taller buildings.
What is the difference between a Miami-Dade NOA and a Florida Product Approval?
A Notice of Acceptance is issued by Miami-Dade County after review of HVHZ test reports, and it carries an expiration date. A Florida Product Approval is issued through the Florida Building Commission and has an FL number. In Miami-Dade and Broward, use either an NOA or a Florida Product Approval that is approved for use in the HVHZ. In Palm Beach County and the rest of the state, a Florida Product Approval or an NOA is accepted.
How can I tell if my windows are hurricane-rated?
Look for a permanent label on the frame that names the manufacturer and the approval, and ask for the permit records and approval documents from the installation. Then look the NOA up on the Miami-Dade Product Control search or the FL number on floridabuilding.org, and match the model, size, and glass. An etching in the glass corner usually identifies the glass or laminate, not the whole window assembly. No label and no records usually means the opening cannot be shown to be protected.
Does a hurricane rating mean the window will not leak?
Not exactly. Approval testing includes a water test at a fraction of the design pressure, and Performance Grade ratings include water resistance. That test does not cover every storm, and many leaks start at the installation, the sealant, or the wall around the window. Correct anchoring, flashing, and sealing as the approval describes matter as much as the rating.
Hurricane-rated windows and doors, matched to each opening
National Glass & Construction quotes impact windows and doors for South Florida homes, with product approvals checked against each opening's pressures, including HVHZ approvals in Miami-Dade and Broward. This site is the guide. The estimate comes from National Glass.