Florida adopted the 8th Edition of the Florida Building Code (FBC) with an effective date of December 31, 2023. For Southwest Florida homeowners planning a reroof—or still repairing after recent storm seasons—several roofing provisions meaningfully affect scope, pricing, and long-term resilience.
The short list (what actually changes your project)
- Secondary Water Barrier (SWR) is explicit on reroofs. When a roof covering over a wood deck is removed and replaced, an SWR must be installed. The code now states this plainly and removes separate HVHZ language so the rule reads uniformly statewide. Exceptions: low-slope continuous roof systems (<2:12) and clay/concrete tile installed per FBC are deemed compliant.
- Underlayment options are tightened—and documented. The 8th Ed. organizes steep-slope underlayment into three compliant methods:
- Full self-adhered (ASTM D1970) over the entire deck;
- Seam-tape method (≥3-3/4″ AAMA 711/ASTM D1970 at every deck joint) plus a full approved underlayment;
- Two-ply nailed underlayment with clarified laps and a defined cap-nail grid (including metal-cap requirements at higher wind speeds).
- Drip edge & edge detailing get stricter. The code clarifies how underlayment and drip edge interface, allows self-adhered underlayment over a primed flange, requires a 4-inch strip of roofing cement at eaves and rakes for asphalt shingles, and tightens fastener spacing to 4 inches on center at higher wind or taller buildings (otherwise 12″ o.c.). These perimeter details directly affect wind performance.
- Keeping an existing peel-and-stick layer can be allowed. If you already have a self-adhered membrane on the deck and (where required) deck re-nailing can be verified, the code permits overlaying with an approved underlayment instead of tearing the membrane off—often saving time and money.
- The “25% rule” still exists—with a key exception. If 25% or more of a roof (or roof section) is repaired/replaced within any 12-month period, that roof section must be brought up to the current code—except when the existing system was built under FBC 2007 or later, in which case only the repaired/replaced portion must meet today’s code. This exception matters for post-2007 homes.
- Low-slope edges and gutters are performance-tested. Where gutters are used to secure the membrane edge on low-slope roofs, they must meet wind-resistance testing (SPRI GT-1). This often applies to patio covers, lanais, and flat sections.
What this means for a typical SWFL reroof
1) Expect an SWR in your scope
Whether by full self-adhered or seam-taped deck plus underlayment, the SWR is your backup when wind strips shingles, tiles, or metal. Tile systems that follow the FRSA-TRI manual fulfill the requirement by design; most shingle/metal roofs will include a clearly identified SWR step on the proposal.
2) Underlayment isn’t “one size fits all” anymore
Installers must follow one of the three methods—with labeled products to specific ASTM/AAMA standards and defined cap-nail patterns. If your property’s mapped wind speeds are high, you’ll likely see metal cap nails specified in the underlayment line items.
3) Perimeter work is not a minor detail
Plans and inspections will look closely at drip-edge sequencing, laps, cement at eaves/rakes, and fastener spacing. If your home is taller or in higher wind zones, the 4″ o.c. edge fastening will be enforced. These are the details that keep coverings from peeling back.
4) Overlay of existing peel-and-stick (case-by-case)
Where an older self-adhered membrane exists, your contractor may be able to verify deck re-nailing and overlay with a compliant underlayment—subject to local approval and manufacturer compatibility—reducing tear-off exposure and cost.
5) The 25% rule & planning repairs strategically
For homes built 2007 or later, large repairs no longer automatically force full replacement of the roof section; only the affected area must meet the current code. For pre-FBC homes, be ready for full-section upgrades once you cross the threshold.
6) Still in force during reroof: deck & strap checks
During roof replacement, inspectors can require roof-deck re-nailing per the Existing Building Code and, for certain higher-valued homes in wind-borne debris regions, roof-to-wall connection improvements up to statutory cost caps. Expect questions about insured or assessed value and wind region designation.
Homeowner checklist (use this on bids & during inspections)
- Underlayment method: Which of the three code-compliant paths is specified? Are product standards (ASTM/AAMA) listed on the submittals? (Florida Roof)
- SWR details: If using seam tape, is it ≥3-3/4″ and rated to AAMA 711 (Level 3) or ASTM D1970? (Florida Roof)
- Drip edge interface: Is the flange primed if the self-adhered layer goes over it, and is the 4″ roofing cement bedding included at eaves and rakes? (Florida Roof)
- Edge fastening: Does your location/mean roof height trigger 4″ o.c. edge fasteners (instead of 12″)? (Florida Roof)
- Existing peel-and-stick: If present, will the contractor verify deck re-nailing and submit overlay documentation? (Florida Building Association)
- Low-slope edges/gutters: If a membrane roof secures at the gutter, does the product meet SPRI GT-1? (Florida Roof)
Bottom line for SWFL
The 8th Edition FBC tightens underlayment, SWR, and edge requirements that directly affect hurricane performance—and clarifies pathways (and exceptions) that can save cost while keeping homes drier when coverings are compromised. If you’d like a code-savvy reroof plan, Swift Roofing Services can translate these provisions into a clean scope, handle permitting, and manage inspection documentation start to finish.