ADU Rules in St. Johns County, FL: What Ponte Vedra & St. Augustine Homeowners Need to Know in 2026 | Sunshine State Pro

Ponte Vedra, Nocatee, and St. Augustine homeowners keep asking the same question: does Jacksonville's ADU ordinance apply here? It doesn't. St. Johns County runs its own rulebook, and the City of St. Augustine runs a different one on top of that inside city limits. If you're planning a backyard ADU anywhere between the Duval County line and the Matanzas River, the rules that actually govern your project depend on which side of a city boundary your lot happens to sit on.

Sunshine State Professional Services builds ADUs across Northeast Florida, including Nassau, Duval, and St. Johns counties, so we get asked to untangle this more than almost anything else. Here's what's actually true for St. Johns County right now, what's different inside St. Augustine, and what it costs to get one built.

Florida Doesn't Have a Statewide ADU Law — Your County or City Sets the Rules

A lot of homeowners have heard that Florida "passed a law" requiring every city to allow ADUs. That's not accurate as of mid-2026. Florida Statute §163.31771 allows local governments to adopt ordinances permitting ADUs — it does not require them to, and it sets no statewide size, setback, or occupancy standard. Two bills that would have created a real statewide mandate, Senate Bill 184 in 2025 and Senate Bill 48 in 2026, both failed in the Legislature and are not law ( source).

The practical result: whether you can build an ADU, how big it can be, and whether you need owner-occupancy or can rent it out are all decided locally, and they can change from one side of a street to the other. The bill that would have standardized this statewide is expected to be reintroduced when the Legislature reconvenes in January 2027, but until then, the only rules that matter are the ones your specific city or county has already written ( source).

Unincorporated St. Johns County: Ponte Vedra, Nocatee & the "Accessory Family Unit" Code

If your address is in Ponte Vedra, Nocatee, Julington Creek, or any other unincorporated part of St. Johns County, meaning it's not inside the city limits of St. Augustine or St. Augustine Beach, you're not working with an "ADU ordinance" at all. St. Johns County's own Land Development Code addresses this under Section 38.0, which governs what the county calls an "Accessory Family Unit," cross-referenced against LDC 2.02.04.B.16 and the county's Planning and Zoning Vested Areas (PZVA) Section VIII.L. It's the same concept homeowners know as an ADU or in-law suite, just a different label in the county's code.

That naming difference matters more than it sounds. Contractors and homeowners who search only for "ADU rules" sometimes miss that St. Johns County's own locational, occupancy, and size requirements live under this "Accessory Family Unit" heading instead. Before you have plans drawn, confirm your parcel's zoning district and the current version of Section 38.0 directly with St. Johns County Growth Management, code sections get renumbered, and a contractor working from an outdated PDF is a common source of redesign headaches partway through permitting.

Building Inside St. Augustine City Limits: Historic District Review Changes the Timeline

The City of St. Augustine is a separate jurisdiction from the surrounding county, with its own building department and its own review process, and it's not the same as St. Augustine Beach, which is a third, separate municipality. If your lot falls inside the city, expect these specifics: standard residential setbacks run 5 feet on the side and 10 feet in the rear, maximum structure height sits at 25–35 feet, and one dedicated parking space is required for the ADU. There is no owner-occupancy requirement, the city allows both the primary home and the ADU to be rented to separate tenants ( source, last verified April 2026).

The one factor that catches almost every St. Augustine homeowner off guard is the National Historic Landmark District. If your property sits inside it, you'll need a Certificate of Appropriateness from the city's Historic Architectural Review Board (HARB) before a building permit can even be issued, a design-compatibility review focused on materials, massing, and street visibility that typically adds 4 to 12 weeks to the timeline on top of the standard 4–7 week permit process. It's a close cousin of the Certificate of Appropriateness process Jacksonville's own historic districts use, which we've broken down in detail for Jacksonville homeowners. Anastasia Island parcels add a second layer: many sit in FEMA AE flood zones, which can tack on another 2–4 weeks for elevation review, and ocean-facing lots in Zone VE face much tighter restrictions on new construction.

What an ADU Actually Costs in St. Johns County

Permit and fee totals for a St. Augustine ADU typically run $7,300–$17,000 before construction even starts, broken down roughly as: building permit fees $1,500–$3,500, impact fees $4,000–$9,000, plan review $400–$900, and utility connection fees $1,200–$3,000. Add HARB review costs on top if your property is in the historic district. Actual construction costs for a detached ADU in the area run an estimated $100,000–$210,000 depending on size and finish level (per the same source cited above, last verified April 2026).

Those figures are for the City of St. Augustine specifically; unincorporated county permitting under the Accessory Family Unit code follows a different fee schedule, which is why getting a written, project-specific quote matters more than working off a rule of thumb. If you're comparing this against a project just across the county line, our guide to building an ADU on a septic system in Nassau County walks through a similar cost breakdown for a different set of local rules, and our roundup of ADU financing options covers ways to structure the upfront cost.

Renting Your ADU: Short-Term vs. Long-Term Rules

St. Augustine draws an estimated 5 to 7 million visitors a year, and that tourism demand shows up directly in what an ADU can earn there. The city does not prohibit short-term rentals at the municipal level, though a Florida DBPR license is required and St. Johns County collects a 6% Tourist Development Tax on short-term stays. Reported ranges for the area run roughly $1,300–$2,400 a month for long-term leases, or $120–$320 a night for short-term stays, with weekly rates near Old Town running higher during peak tourism periods (same source as above).

Unincorporated St. Johns County is a different conversation, and this is exactly why it's worth confirming your specific jurisdiction before you plan around rental income: rules that apply inside St. Augustine city limits do not automatically apply in Ponte Vedra or Nocatee. If short-term rental income is part of your reason for building, confirm current occupancy and rental restrictions with St. Johns County Growth Management (for unincorporated parcels) or St. Augustine Planning and Building (for city parcels) before you finalize a design.

How Sunshine State Handles Your St. Johns County ADU

We're a licensed general contractor built the way a lot of our clients say they wish more contractors were: we started at ground level, doing the actual trade work, before earning the license to run projects ourselves. That background shows up in how we handle permitting-heavy jobs like this one, we don't hand you a generic plan and let you find out about HARB or setback issues during the permit review. Our in-house team of estimators, project coordinators, and project managers handles the zoning confirmation, permit applications, and inspections directly with St. Johns County or St. Augustine, so you're not the one making follow-up calls to Growth Management.

If you're weighing an ADU against a traditional room addition for the same lot, our ADU vs. home addition comparison is a useful starting point, and if hurricane performance is a concern for a coastal St. Johns County lot, we cover the construction details in our guide to hurricane-resistant ADU construction. Whatever the jurisdiction, our goal is the same one we bring to every project: you understand exactly what's happening at each step and you're genuinely happy with the result, not just the fact that it's finished.

Sunshine State builds throughout our St. Johns County service area, including Ponte Vedra and St. Augustine. You can see our full ADU construction process or call (904) 517-2427 for a free, no-obligation consultation on your specific parcel.

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