Fort Pierce

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.

• 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.

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.

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.