Where Missiles Fly

A wind-borne debris region (WBDR) is an area where hurricanes can turn everyday objects into dangerous projectiles. In these zones, buildings must use impact-resistant glazing or protective shutters because flying debris is the primary cause of building envelope failure during hurricanes. Once a window breaks, wind enters the building, pressurizes it from inside, and can blow off the roof.

Wind-borne debris regions in Florida include: (1) Areas within 1 mile of the coast where the basic wind speed is 130 mph or greater, (2) All of Miami-Dade and Broward counties (the HVHZ), and (3) Hawaii. The exact boundaries are defined by the Florida Building Code based on ASCE 7 wind speed maps. If you're near the coast in South Florida, you're almost certainly in a WBDR.

There are two missile levels: Large Missile (a 9 lb, 8-foot 2x4 lumber traveling at 34 mph) for lower buildings and critical facilities, and Small Missile (ten 2-gram steel balls at 130 mph) for upper floors of high-rises. The large missile test simulates construction debris - the most common dangerous projectile. Miami-Dade has the most stringent requirements, mandating large missile protection for the entire building at all heights.

Yes, all of Miami-Dade County is within the wind-borne debris region AND the High Velocity Hurricane Zone (HVHZ). Every building must have impact-resistant glazing or approved protective systems (shutters) on ALL exterior openings - windows, doors, skylights, and garage doors. There are no height exemptions in the HVHZ; even the 50th floor needs large missile protection.

WBDR (Wind-Borne Debris Region) is defined by ASCE 7 and the Florida Building Code, requiring impact protection based on distance from coast and wind speed. HVHZ (High Velocity Hurricane Zone) only includes Miami-Dade and Broward counties and has even stricter requirements - it's like WBDR plus additional testing standards (Miami-Dade NOA approval) and no height exemptions. Think of HVHZ as "WBDR plus extra."