ADU Pass
St. Lucie County
ADU Pass helps homeowners in St. Lucie County, Florida navigate the permit paperwork for building an accessory dwelling unit. We cover 2 cities and 14 ZIP codes in this county.
County ADU details
County ADU ordinance
St. Lucie County (Atlantic coast, immediately north of Martin County and south of Indian River County) regulates accessory dwelling units on parcels in the unincorporated county through the St. Lucie County Land Development Code (LDC), which addresses 'accessory dwelling units,' 'guest houses,' and 'caretaker residences.' St. Lucie is a Treasure Coast county experiencing rapid population growth — Port St. Lucie is one of the fastest-growing cities in Florida and the nation, having grown from ~88,000 in 2000 to ~240,000+ by 2024. Fort Pierce (county seat, historic center) and Port St. Lucie (dominant population center, master-planned suburban) are the principal municipalities. Florida has no mandatory statewide ADU preemption — § 163.31771 Fla. Stat. is permissive only. As of 2026-04-20, St. Lucie County permits one ADU per single-family parcel in residential zoning districts (RS-1, RS-2, RS-3, RS-4, AG-1) subject to size caps (typically 800 sqft or 40% of primary, whichever is less; larger allowances on AG-1 Agricultural parcels), setback conformance, height limits, and owner-occupancy. The county has extensive Atlantic coastal frontage (Hutchinson Island — partially in St. Lucie, partially in Martin; North Hutchinson Island; South Hutchinson Island; Jensen Beach waterfront in Martin but adjacent), Indian River Lagoon frontage, and inland citrus / cattle / conservation lands. Hurricane Frances (2004) and Hurricane Jeanne (2004) were the historic major events; Hurricane Nicole (Nov 2022) and Hurricane Milton (Oct 2024) delivered post-2020 coastal damage. Pending 2026 state legislation (SB 48 / HB 313) would preempt sub-1,000-sqft caps — St. Lucie's 800-sqft cap requires upward adjustment.
Code citations:
- St. Lucie County Land Development Code — ADU and accessory-use provisions
- St. Lucie County Comprehensive Plan — Future Land Use and Coastal Management Elements
- St. Lucie County Board of County Commissioners — agenda archive
State-floor overlay: Florida has no mandatory statewide ADU preemption. § 163.31771 Fla. Stat. is permissive only. Pending 2026-session SB 48 / HB 313 would preempt sub-1,000-sqft caps and single-family-zone bans effective December 1, 2026 if enacted. St. Lucie's 800-sqft cap requires upward adjustment. Live Local Act applies to commercial / industrial / mixed-use. Florida HOA / condominium statutes do NOT preempt association-level ADU restrictions — St. Lucie has enormous HOA jurisdiction in Port St. Lucie's master-planned communities (St. Lucie West, Tradition, Torino, Crosstown, Verano, Reserve), Hutchinson Island condominiums, and Fort Pierce unincorporated fringe subdivisions, where covenants commonly bar ADUs.
Adopting body: St. Lucie County Board of County Commissioners
County permitting (unincorporated parcels)
St. Lucie County Planning & Development Services Department is the combined planning / zoning / building / floodplain permit authority for parcels in the unincorporated county. Unincorporated St. Lucie covers approximately 420 square miles (about 70% of the 572 sqmi total land area; coastal exposure makes unincorporated share smaller than some Florida counties). Incorporated municipalities are Fort Pierce (county seat), Port St. Lucie (dominant city), and St. Lucie Village (tiny). Principal unincorporated communities include Hutchinson Island (partially), White City, Lakewood Park, Indrio, Fort Pierce unincorporated fringe, Ankona, and inland-west rural parcels. St. Lucie is a CRS Class 6 community for NFIP. All of St. Lucie County is WBDR at 150 mph inland / 160-170 mph Atlantic barrier-island and immediate coastal. Planning & Development Services operates one-stop permit intake.
Process overview: ADU approval in unincorporated St. Lucie County is a combined zoning / building / floodplain / environmental review. Typical sequence: (a) confirm parcel zoning, FLU, CHHA, FIRM, Indian River Lagoon Protection Zone via St. Lucie Property Appraiser and Planning & Development Services GIS; (b) submit Building Permit through portal with site plan, floor plans, elevations, FBC compliance (150-170 mph per location), flood compliance for SFHA, SFWMD stormwater, DOH septic for on-site septic parcels; (c) zoning review; (d) building plan review; (e) St. Lucie County Fire District access/water review; (f) environmental review for Indian River Lagoon frontage; (g) permit issuance, construction, inspections, CO.
Impact fees: St. Lucie County imposes transportation, parks, St. Lucie County Schools, law enforcement, and library impact fees. For a typical ADU in unincorporated St. Lucie County, total impact fees run approximately $10,000-$15,000 (as of 2026-04-20). Water/sewer connection fees through St. Lucie County Utilities or Fort Pierce Utilities Authority add $3,500-$7,000 in served areas. (schedule)
County assessor
St. Lucie County Property Appraiser maintains parcel-level assessment records for all St. Lucie real property. Florida Save Our Homes (§ 193.155) / 10% non-homestead cap apply. ADU treated as new construction added to just value at completion-year fair market value; primary's SOH base not reset. Port St. Lucie's rapid growth 2000-2024 drove many non-homestead parcels to 10% cap. Post-Nicole / Milton, Property Appraiser issued § 197.319 prorated refunds on destroyed coastal residences. The Property Appraiser administers Agricultural Classification on qualifying inland-west citrus and cattle parcels.
Assessment policy: New-construction additions occur at annual roll-over following CO. Typical 600-800 sqft ADU adds $100,000-$180,000 just value, yielding supplemental annual tax of $1,800-$3,300 at aggregate millage ~1.8-2.0%. Hutchinson Island barrier-island ADUs at higher end of construction-cost range.
County overlays (8)
St. Lucie County administers overlays materially affecting ADU siting: (1) FEMA SFHA covering Hutchinson Island (partial), Atlantic coastal frontage, Indian River Lagoon frontage, St. Lucie River system, North Fork / South Fork St. Lucie River; St. Lucie is CRS Class 6; post-Nicole / Milton FIRM revisions raised BFEs; (2) Florida Building Code Wind Borne Debris Region at 150-170 mph; (3) Coastal High Hazard Area (CHHA); (4) Florida DEP Coastal Construction Control Line (CCCL) along Atlantic shoreline; (5) Indian River Lagoon Protection Zone — county-administered buffer protections supporting the lagoon-wide TMDL; (6) South Florida Water Management District (SFWMD) consumptive-use and stormwater; (7) St. Lucie County International Airport AIA; Treasure Coast International Airport AIA (in Fort Pierce); (8) Savannas Preserve State Park overlay — state-protected wetland preserve; (9) Adams Ranch / Savannas / Ten Mile Creek conservation overlays.
- FEMA Special Flood Hazard Areas (SFHA) — NFIP (St. Lucie CRS Class 6, post-Nicole/Milton FIRM) — St. Lucie administers FEMA NFIP. SFHA covers Hutchinson Island, Atlantic coastal frontage, Indian River Lagoon, and St. Lucie River. CRS Class 6 gives 20% NFIP premium discount.
- Florida Building Code Wind Borne Debris Region (WBDR) — 150 mph inland / 160-170 mph Atlantic-coastal and barrier-island. Impact-rated glazing or shutters required.
- Coastal High Hazard Area (CHHA) — St. Lucie Comp Plan — CHHA covers Hutchinson Island, Atlantic frontage, and lagoon-adjacent surge-exposed parcels.
- Florida Coastal Construction Control Line (CCCL) — FDEP — CCCL along Atlantic shoreline. Seaward of CCCL requires FDEP permit.
- Indian River Lagoon Protection Zone — The Indian River Lagoon is a federally-designated estuary of national significance; St. Lucie's Lagoon Protection Zone imposes nutrient-loading controls, seagrass-habitat protections, and stormwater enhancements on lagoon-frontage parcels. ADUs on lagoon-frontage parcels face tightened requirements.
- South Florida Water Management District (SFWMD) — SFWMD is St. Lucie's water management district. Standard residential consumptive-use exemption below ~6,000 gpd. ERP review for additions beyond minor footprint.
- Treasure Coast International Airport (FPR) AIA — Treasure Coast International Airport (Fort Pierce) is a major GA field. AIA covers central-county parcels near Fort Pierce. Part 77 and Part 150 reviews apply.
- Savannas Preserve State Park overlay — Savannas Preserve State Park protects wetland and sand-ridge habitat on the St. Lucie / Martin border (~6,000 acres). Adjacent parcels face buffer-protection and biological-review requirements.
Known county issues (4)
- other — Florida HOA statute does NOT preempt association restrictions. Port St. Lucie's extensive master-planned communities (St. Lucie West, Tradition, Torino, Crosstown, Verano, Reserve) bar ADUs regardless of county or city zoning. Hutchinson Island condominiums similarly bar ADUs. Non-HOA parcels (older Fort Pierce neighborhoods, unincorporated Indrio / Lakewood Park / White City) are the practical ADU landscape.
- other — Nicole delivered significant Atlantic Coast erosion and damage; Milton delivered additional rainfall / wind damage. Citizens Property Insurance premiums for coastal St. Lucie ADUs run $4,000-$8,500/year. Hutchinson Island post-Nicole reconstruction continued through 2024-2025.
- policy-review — St. Lucie's 800-sqft ADU cap requires upward adjustment if SB 48 / HB 313 enacts December 1, 2026.
- other — Indian River Lagoon Protection Zone imposes nutrient-loading controls, seagrass protections, and stormwater enhancements. Performance-based treatment septic systems may be required on parcels not served by central sewer, adding $15,000-$30,000 to ADU cost.
Florida state — ADU law and programs
State ADU law
Florida does NOT currently have a statewide ADU preemption law in effect. Florida Statutes § 163.31771 (enacted 2004, last amended 2020) is permissive — it authorizes local governments to adopt ADU ordinances but does not require them to. ADU rules are therefore set municipality-by-municipality: Miami-Dade, Orlando, St. Petersburg, Tampa, and a growing set of Florida cities have their own ordinances; many smaller counties and cities still prohibit or restrict ADUs by default. A preemption bill (SB 48 / HB 313) is pending in the 2026 legislative session and is likely to pass given that its 2025 predecessor cleared the Senate 37-0 and House 97-10 before dying on a procedural amendment dispute.
- Florida Statutes § 163.31771 — Accessory dwelling units — Permissive (not mandatory) statute. Defines an ADU as 'an ancillary or secondary living unit, that has a separate kitchen, bathroom, and sleeping area, existing either within the same structure, or on the same lot, as the primary dwelling unit.' Authorizes — but does not require — local governments to adopt ordinances allowing ADUs in single-family residential zones. Contains no size caps, no owner-occupancy rules, no HOA preemption. All substantive rulemaking is local.
State financing programs
Florida Housing Finance Corporation (FHFC) does not operate an ADU-specific state loan or grant program. FHFC's primary affordable-housing lever at the ADU tier is the State Housing Initiatives Partnership (SHIP), which distributes state documentary-stamp-tax revenue to all 67 counties and 52 entitlement cities for locally-administered housing programs — some of which may fund ADU construction at the local level (notably Orange County's Affordable ADU Loan Program, run through the Orange County Housing Finance Trust). FHFC's FL Assist down-payment programs and HFA Preferred / HFA Advantage conventional loans apply to ADU-eligible primary residences but do not single out ADUs. Proposed CS/SB 1440 would create a state property-tax exemption of up to 100% of assessed value for an ADU rented at affordable rates.
State housing programs
Florida does not currently operate a statewide pre-approved ADU plan catalog (unlike California or Washington). State-level ADU implementation is driven by (a) the permissive § 163.31771 which lets willing jurisdictions adopt ordinances, (b) SHIP pass-through funding to local ADU programs (Orange County's Affordable ADU Loan Program is the model), and (c) the affordable-housing property-tax exemption under the Live Local Act (SB 102 / SB 328). The Department of Economic Opportunity (DEO) — now reorganized as the Department of Commerce — provides technical assistance to local governments but no statewide ADU-specific mandate or program. Major counties (Miami-Dade, Orange, Pasco, Hillsborough, Pinellas, Broward) have published their own ADU ordinances and guidance documents.
Federal (United States) — ADU-relevant rules and programs
Federal ADU law
The United States has no federal statute that directly regulates accessory dwelling unit entitlement or design. Land-use authority over ADUs resides with states and local governments under the traditional police power. Federal engagement is limited to financing (Fannie/Freddie/FHA/VA/USDA), flood insurance (FEMA/NFIP), and discretionary housing programs (HUD), which are recorded in sibling sections of this file.
Federal financing programs
Federal housing-finance agencies and GSEs set nationwide underwriting rules that govern whether an ADU can be financed, appraised, and counted toward mortgage qualifying income. The relevant actors are Fannie Mae, Freddie Mac, FHA (HUD), VA, and USDA Rural Development.
Federal tax credits
There is no ADU-specific federal tax credit. ADUs may incidentally qualify for existing federal energy-efficiency and clean-energy tax credits when the ADU construction includes qualifying measures.
Federal housing programs
HUD administers several discretionary programs that can fund ADU-related activity at the grantee's election, but none is an ADU-specific program.