Sources: 2023 Florida Building Code, Residential, Chapter 9; section 553.73, Florida Statutes.
The International Residential Code roofing rules are not enforced in Florida as published. Florida builds homes to the Florida Building Code, which state law (section 553.73) has the Florida Building Commission adopt. Its residential volume, the 2023 Florida Building Code, Residential, Eighth Edition, adopts the 2021 International Residential Code (IRC) with Florida amendments. So the roofing chapter keeps the IRC's structure and section numbers, but the parts that matter in a hurricane state are rewritten.
This guide walks through Chapter 9, Roof Assemblies, as it applies to a house in Central Florida: what stays the same as the IRC, where Florida changes it, and the re-roofing rules that decide what a roof replacement has to include. It is a plain-language summary, not legal advice; the code text and your local building department have the final word. If you are planning a re-roof, our residential roof replacement page explains how we handle the permit and inspections.
How the IRC becomes Florida code
The IRC is a model code written by the International Code Council. On its own it has no force; a state or city has to adopt it. Florida does not adopt it directly. Instead, the Florida Building Commission publishes the Florida Building Code, and the residential volume starts from the IRC, then adds, deletes and replaces sections.
You can see the edits in the text. Some IRC sections are kept word for word. Others are marked "Reserved," which means Florida removed them.
Others point to Florida-only standards, such as the Roofing Application Standards (RAS) and the tile installation manual written for Florida's high winds. And one line at the top of the chapter sends South Florida's High-Velocity Hurricane Zone to a separate chapter altogether.
What stays the same as the IRC
The basics of a shingle roof read much the same in both codes. In the Florida residential code:
- Asphalt shingles are fastened only to solidly sheathed decks (R905.2.1)
- Asphalt shingles are used only on roof slopes of 2:12 or greater (R905.2.2)
- Shingle nails are galvanized steel, stainless steel, aluminum or copper, at least 12-gauge with a 3/8-inch head, and long enough to go at least 3/4 inch into the sheathing, or through it where it is thinner (R905.2.5)
- Each strip shingle gets the number of fasteners the manufacturer requires, and never fewer than four (R905.2.6)
Those are the numbers a homeowner is most likely to hear quoted from "the IRC," and on a Central Florida house they are also the Florida numbers.
Where Florida rewrites the roofing chapter
Underlayment is a wind detail, not just a felt layer
Florida's biggest change is under the shingles. Section R905.1.1.1 gives three ways to underlay a shingle or metal roof, each built to keep water out if the covering is torn off in a storm:
- The whole deck covered in a self-adhering polymer-modified bitumen underlayment (ASTM D1970)
- A strip of self-adhering membrane or flashing tape at least 3 3/4 inches wide over every joint in the roof deck, then an approved underlayment over the whole roof
- Two layers of felt or synthetic underlayment, lapped to a set pattern and fastened on a grid with cap nails whose caps are at least an inch across
That is the "secondary water barrier" you will see on a Florida roofing scope. We put underlayment and a secondary water barrier over the whole deck on every re-roof, so the house is watertight before the covering goes on.
No ice barrier
In the IRC, section R905.1.2 covers ice barriers, a cold-climate detail at the eaves. In the Florida code, R905.1.2 Ice Barriers reads simply "Reserved."
Shingles rated for the wind
Section R905.2.6.1 requires asphalt shingles to be tested and classified for wind (ASTM D3161, TAS 107 or ASTM D7158) to match the design wind speed for the site, and the wrapper has to be labeled with the classification. Ask to see it.
Tile follows a Florida manual
Clay and concrete tile slopes and underlayment follow the FRSA/TRI Florida High Wind Concrete and Clay Roof Tile Installation Manual, Seventh Edition (R905.3.2 and R905.3.3), a Florida-specific document.
Metal roof slopes
Section R905.10.2 sets the minimum slope for metal panels: 3:12 for lapped, non-soldered seams with no lap sealant, 1/2:12 with lap sealant, and 1/4:12 for standing seam systems. That is why a standing seam roof can go on a much lower pitch than a lapped panel.
The High-Velocity Hurricane Zone
Section R901.1 sends buildings in the High-Velocity Hurricane Zone to Chapter 44 instead. That zone is in South Florida and Orlando sits outside it, so for a house here Chapter 9 is the chapter that applies.
Florida residential roofing rules at a glance
| Topic | What the Florida residential code says | Section |
|---|---|---|
| Shingle slope | 2:12 or steeper | R905.2.2 |
| Shingle fasteners | Manufacturer's count, at least 4 per strip shingle | R905.2.6 |
| Underlayment | One of three secondary water barrier methods | R905.1.1.1 |
| Ice barrier | Reserved (removed) | R905.1.2 |
| Shingle wind rating | Tested, classified and labeled for the site's wind speed | R905.2.6.1 |
| Tile | FRSA/TRI Florida high-wind tile manual, 7th edition | R905.3.2 |
| Standing seam metal slope | 1/4:12 minimum | R905.10.2 |
| Repairs over 25% | Whole roof or section to current code, unless built to the 2007 code or later | R908.1.1 |
| Two existing roofs | Tear off before re-roofing | R908.3 |
Source: 2023 Florida Building Code, Residential, Eighth Edition, Chapter 9.
Re-roofing: the rules that shape a replacement
Section R908, Existing Roofing, is the part of the chapter most homeowners actually run into, because it decides what a roof replacement has to include.
The 25% rule
Section R908.1.1 says no more than 25% of a roof or roof section may be repaired, replaced or re-covered in any 12-month period unless the whole roof or section is brought up to code. The exception: if the roof was built, repaired or replaced under the 2007 Florida Building Code or later, only the part being worked on has to meet the current code. The same exception sits in section 553.844, Florida Statutes. Our guide to roof replacement cost in Orlando explains what that means for a storm-damaged roof.
When the old roof has to come off
Section R908.3 requires a full tear-off when the existing roof is water-soaked or too deteriorated to hold new roofing, when it is wood shake, slate, clay, cement or asbestos-cement tile, when there are already two or more roofs on the house, or when blisters have not been cut open and secured. A standing seam metal system that carries its own load to the structure is the exception. We go further on every house: full tear-off to bare deck, because a second layer hides the deck and adds weight the next roofer has to remove.
Deck nailing and the secondary water barrier
On a house built before the Florida Building Code (the section does not apply to structures permitted under it), when a roof covering over a wood deck is removed and replaced, section R908.7 lets the roofing contractor bring the deck attachment up to standard and add a secondary water barrier. R908.7.1 sets out when the existing nailing counts as sufficient and when more nails are added. R908.7.2 requires the secondary water barrier when the covering is removed and replaced, with exceptions for continuous low-slope roofs and for tile roofs installed to the Florida code. Section 553.844 is the reason these items exist: the Legislature told the Commission to fold secondary water barriers and stronger deck attachment into re-roofing on older homes.
Roof-to-wall connections on some higher-value homes
Section R908.8 adds a step for older homes, again those not permitted under the Florida Building Code, in the wind-borne debris region with an insured value, or a just value for tax purposes, of $300,000 or more: the roof-to-wall connections are improved during the re-roof. The code caps that work at a 15% increase in the cost of re-roofing. Whether your house falls in the wind-borne debris region depends on its location on the wind map, which your building department can confirm.
Who can do the work
Roofing in Florida is licensed under Chapter 489 of the Florida Statutes. We pull the permit under our own certified roofing contractor license, CCC1330329. Two inspections usually follow: one after tear-off and dry-in, when the inspector checks the deck attachment and underlayment, and a final that closes the permit.
The law does let a homeowner act as their own contractor on their own house in some cases. Section 489.103(7) covers an owner building or improving a one- or two-family home they occupy and do not offer for sale or lease, with the owner supervising the work directly. It also covers an owner repairing or replacing shingles on a one-, two- or three-family home after an event the Governor declares a state of emergency. Owner-builders still pull a permit and pass the same inspections, and the house has to meet the same code.
What to ask a roofer
You do not need to read the code to hold a roofer to it. Ask these before you sign:
- Which secondary water barrier method goes on the deck, and does it cover the whole roof?
- Is the old roof coming off to bare deck, and how is deck repair priced if the wood is bad?
- Will the deck nailing be checked and brought up to code during the re-roof?
- What wind classification is on the shingle wrapper?
- Who pulls the permit, under which license, and do I get the closed permit at the end?
A scope from us answers each of those in writing, with photos of the deck before it is covered. We work across Orlando, Altamonte Springs, Kissimmee and the surrounding communities. To see how a code-compliant re-roof runs from tear-off to closed permit, read our residential roof replacement page or schedule an inspection.