Florida HVHZ Roofing Requirements

High-Velocity Hurricane Zone (HVHZ) covers Miami-Dade and Broward Counties. The broader Florida wind-borne debris zones extend along the entire Florida coast and inland, with separate rules.

Florida's High-Velocity Hurricane Zone (HVHZ) — Miami-Dade and Broward Counties — has the strictest residential roofing requirements in the United States. The Florida Building Code, Building (FBC-B) 8th Edition Chapter 15 and Chapter 16 set design wind speeds (Vult) of 175 mph in Miami-Dade and 170 mph in Broward for Risk Category II construction (essential facilities at Risk Cat IV are 195 / 185 mph). The HVHZ requires Miami-Dade County Notice of Acceptance (NOA) approval for every roof component and mandates a 6-nail HVHZ attachment pattern. Re-roof permitting is governed by the Florida Existing Building Code (FBC-EB) "25% Rule" in §706.1.1, as modified by SB-4D (effective May 26, 2022).

Outside HVHZ, the rest of Florida operates under FBC wind-borne debris zones at 140 to 160 mph design wind speeds. Shingle classifications, fastening schedules, and underlayment requirements still apply but without the Miami-Dade NOA process. The FBC 8th Edition (2023) is currently in effect statewide; the 2026 update is in technical advisory committee review with no scheduled adoption date as of mid-2026.

This guide consolidates the FBC and Miami-Dade NOA requirements for residential asphalt shingle roofing in the HVHZ, the wind-zone classifications across the rest of Florida, the fastener schedules and underlayment rules, and the permitting trigger for re-roofs. It links into the roofing calculator with HVHZ presets that adjust default shingle rating and fastener pattern.

HVHZ Wind Speed and Shingle Class

The HVHZ design wind speed (Vult) is 175 mph in Miami-Dade County and 170 mph in Broward County for Risk Category II construction. Risk Category IV essential facilities (hospitals, emergency operations centers) are 195 mph in Miami-Dade and 185 mph in Broward. Asphalt shingles installed in the HVHZ must carry an ASTM D7158 Class H rating AND a Miami-Dade County Notice of Acceptance (NOA) issued by the manufacturer for the specific shingle product. Class G and lower-rated shingles are not permitted. The NOA process is in addition to ASTM testing — even a Class H shingle without a current Miami-Dade NOA cannot be installed in the HVHZ.

Fastener Schedule (HVHZ)

Asphalt shingle fasteners in the HVHZ are 6 nails per shingle, minimum, regardless of slope or shingle type. The standard non-HVHZ pattern is 4 nails for slopes ≤21:12 and 6 nails for steeper slopes; HVHZ overrides this and mandates 6 nails everywhere. Nails must be 12-gauge minimum, hot-dipped galvanized or stainless steel, with a minimum 3/8-inch head diameter, and must penetrate ≥3/4 inch into the roof deck OR fully through the deck. Staples and pneumatic crown staples are prohibited. Shingles are aligned to the manufacturer's nail line, and the NOA specifies any product-specific deviations.

Underlayment Requirements

In the HVHZ, self-adhered (peel-and-stick) underlayment is required across the entire roof deck — not just at eaves and valleys. Acceptable products include polymer-modified bitumen self-adhered membrane meeting ASTM D1970 with a current Miami-Dade NOA. Mechanically-fastened synthetic or felt underlayment is not permitted as the primary water barrier in the HVHZ. Outside HVHZ, FBC requires self-adhered underlayment at eaves (extending from the edge to a point 24 inches inside the exterior wall line), valleys, and around penetrations; the field can use ASTM D226 Type II felt or ASTM D4869 underlayment.

Re-Roof Permitting Trigger (25% Rule)

Florida Existing Building Code (FBC-EB) §706.1.1 — the "25% Rule" — historically required that any re-roof affecting more than 25% of total roof area trigger full code compliance for the entire roof. SB-4D, signed May 26, 2022, materially modified this: if the existing roof was constructed or replaced after March 1, 2009 to current FBC compliance, the 25% threshold no longer triggers full replacement (only the affected portion must comply with current code). Older roofs and HVHZ projects still typically face the full 25% threshold. The rule applies to roof coverings; structural sheathing is governed by separate provisions in §706.7.1.

Sheathing Fastening Upgrade

Re-roofs that expose the roof deck during tear-off must upgrade the sheathing nailing pattern to current code per FBC-EB §706.7.1.2 (Table 706.7.1.2 supplemental fasteners for site-built single-family residential). Common pre-2002 Florida homes were nailed at 6 inches on edge / 12 inches in field with 6d nails. Current code requires 8d ring-shank nails (ASTM F1667 classification RSRS-01) at 6 inches on edge / 6 inches in field across the entire deck. The separate §706.7.2 provision governs secondary water-barrier (peel-and-stick) requirements at the deck. The Florida "My Safe Florida Home" program has historically subsidized these upgrades for qualifying homeowners.