The High-Velocity Hurricane Zone (HVHZ) is a Florida Building Code designation with stricter wind and product-approval requirements. Under the code, the HVHZ is Miami-Dade and Broward counties only. Monroe and the rest of the state are not in it.
If your project is in Miami-Dade or Broward, HVHZ rules apply. This guide explains what that means in practice.
Which counties are in the HVHZ
Only Miami-Dade and Broward. This is a common point of confusion. Monroe County (the Florida Keys), despite very high wind speeds, is not in the HVHZ. Wind-borne-debris protection still applies there by wind region.
What the HVHZ changes
In the HVHZ, opening protection (impact-rated windows and doors, or approved shutters) is required, and products must carry an approval valid for the HVHZ, a Miami-Dade NOA or a Florida Product Approval with explicit HVHZ acceptance. Testing to the applicable TAS standards is expected.
How an HVHZ product is actually tested
The HVHZ acceptance behind an impact window is earned through Miami-Dade's Testing Application Standards. In TAS 201, a large missile, a 9-pound 2x4 fired from an air cannon at about 50 feet per second, is shot at the assembly to simulate wind-borne debris. In TAS 202 the unit is loaded with uniform static air pressure to its rated design pressure. Then TAS 203 hits it with roughly 9,000 cycles of alternating positive and negative pressure, reproducing the pressure swings of a passing hurricane.
The bar is that the glass may crack, but the assembly has to keep the building envelope intact, no penetration of the missile and no failure of the anchors or frame. That is the difference between impact glass and an ordinary window, and why the product's approval and its as-installed anchorage both matter.
Questions
What does an 'impact-rated' window actually have to survive?
Under Miami-Dade's test protocols, an HVHZ assembly is struck by a 9-pound 2x4 at roughly 50 feet per second (TAS 201), loaded to its rated pressure (TAS 202), and then cycled through about 9,000 pressure reversals (TAS 203). The glass may crack, but the assembly must keep the envelope sealed and the anchors intact.
Is Broward County in the HVHZ?
Yes. The HVHZ under the Florida Building Code is Miami-Dade and Broward. Both require HVHZ product approvals and opening protection.
Is the Florida Keys (Monroe) in the HVHZ?
No. Monroe County is not in the HVHZ, though its wind speeds are among the highest in the state and wind-borne-debris protection still applies by region.