HVHZ vs Wind-Borne Debris Region: What Hurricane Code Applies Outside Miami-Dade and Broward

We see the same mix-up all the time. A homeowner in Palm Beach Gardens, Stuart or Vero Beach gets a window quote that says "HVHZ compliant" and assumes that's what the code requires. Sometimes it's a perfectly good product. But HVHZ is a specific legal zone, and it covers only two counties. Outside it, a different set of rules decides what your house needs, and knowing them can save money without cutting corners on safety.

Two different zones

Our post on what the High-Velocity Hurricane Zone means for your project explains where the HVHZ came from and how its tests work.

What the wind-borne debris region is

In a hurricane, the wind picks up roof tiles, branches, fence boards and anything else that's loose, and throws them at houses. If a window breaks, wind and rain get inside, pressure builds under the roof and the damage multiplies. The wind-borne debris region, often shortened to WBDR, is where the building code says that risk is high enough to require protected openings.

Under the current Florida Building Code, an area inside the hurricane-prone region is in the WBDR if either of these is true:

• The ultimate design wind speed is 140 mph or more. This alone puts the location in the region, no matter how far it is from the water.
• The design wind speed is 130 mph or more, and the site is within one mile of the coastal mean high water line where open-water exposure exists upwind.

Being in the WBDR is what triggers the requirement for impact-rated glazing or approved shutters on new homes, additions and replacement openings. It also matters for reroofing: on some older buildings in the WBDR, a reroof can require improving the roof-to-wall connections, with the cost of that work capped at 15 percent of the reroofing cost.

What that means where you live

• Miami-Dade and Broward. HVHZ. Every exterior product needs HVHZ approval, and the structure is designed to the zone's wind speeds. See our guides to Fort Lauderdale, Hollywood and Miami Beach.
• Palm Beach County. Not HVHZ. Palm Beach County's building division states that all of unincorporated Palm Beach County is within the wind-borne debris region, so openings need impact protection, with products approved through Florida Product Approval. Our Boca Raton guide covers how that plays out there.
• The Treasure Coast and Space Coast. Martin, St. Lucie, Indian River and Brevard counties are not in the HVHZ. Whether a specific address is in the WBDR depends on its mapped wind speed and its distance from the coast, so check the address rather than assuming. Much of the Atlantic coast is in the region.
• Central Florida and the Panhandle. Many inland areas fall below the thresholds today, but that could change; see the next section.

The definition may change

The WBDR definition has been a moving target. A newer national standard dropped the word "coastal" from the one-mile rule, which would pull in areas near large inland lakes, and Florida has gone back and forth on adopting that change. A study done for the Florida Building Commission recommended adding inland areas near large bodies of water at 130 to 139 mph, but shrinking the distance from one mile to about 3,000 feet. Proposals for the next edition of the code would expand the region further. If you are building inland near a lake, ask your building department which definition applies on the day you submit.

Do you need HVHZ-rated windows outside the HVHZ?

No, but you might choose them. Outside Miami-Dade and Broward, a window, door or shutter needs a Florida Product Approval whose limits of use cover your wind zone and the design pressure of each opening. A product approved for the HVHZ is tested to tougher protocols, and many carry both a Miami-Dade NOA and a statewide approval, so they can be used anywhere in Florida. They also tend to cost more. Paying for HVHZ approval in Palm Beach or St. Lucie County is a choice, not a code requirement.

What is not optional anywhere is the design pressure. Corners and upper floors see higher pressures than the middle of a wall, so two windows on the same house can need different ratings. Our guides on NOA versus Florida Product Approval and how to look up an NOA show how to read an approval and check the numbers.

Insurance still rewards protection

Whether or not your county is in the HVHZ, protected openings and a well-connected roof can lower your windstorm premium. A wind mitigation inspection documents what your house has; our post on wind mitigation inspections explains what inspectors look for.

The bottom line

HVHZ is the rule in Miami-Dade and Broward only. Everywhere else, check whether the property is in the wind-borne debris region, then buy products with a Florida Product Approval that covers the site's wind speed and each opening's design pressure. We install impact windows and doors and build new homes and additions under both sets of rules across Miami-Dade, Broward and Palm Beach. Ask us what your project needs.