Seminole County

Permits for ADUs on parcels in unincorporated Seminole County are issued by the Seminole County Development Services Department, which consolidates planning, zoning, and building review. Seminole has seven incorporated cities; about 40% of county population lives in unincorporated territory. Unincorporated suburban areas including Fern Park, Goldenrod, Forest City, and Wekiva are the primary markets for ADU permits.

Process overview: An ADU on an unincorporated Seminole parcel is permitted as a combined planning/building permit. Typical workflow: zoning-compliance review, site-plan and construction-drawing submission under Florida Building Code 2023, wind-load review (Seminole sits in approximately the 130-140 mph ASCE 7-22 ultimate design wind-speed zone — Risk Category II residential), plan review, issuance, inspections, and certificate of occupancy. Wekiva Study Area parcels require additional water-quality and septic review. Floodplain parcels along the St. Johns River and tributary corridors require elevation-certificate review.

Impact fees: Seminole County levies transportation, schools, fire-rescue, and public-facilities impact fees on new residential units. The Seminole County School District impact fee is substantial given the suburban-family demographic profile. ADU additions in unity-of-title configurations receive reduced rates in most categories. (schedule)

The Seminole County Property Appraiser maintains parcel-level assessment records for all real property in Seminole County, including parcels within the seven incorporated cities. ADU additions are assessed at just value on completion; Florida's Save Our Homes 3% cap applies to homesteaded primary residences. Most Seminole owner-occupied parcels are homesteaded given the county's suburban-family demographic.

Assessment policy: ADU additions assessed at just value on completion; homesteaded host portion continues under Save Our Homes cap. No county-level ADU abatement or incentive.

Seminole County administers several consequential overlays including the Wekiva Study Area (WSA), which covers substantial western and northern county territory and imposes elevated water-quality, septic, and habitat standards. FEMA floodplain overlays along the St. Johns River (northern county boundary), the Econlockhatchee River, and Lake Jesup / Lake Monroe shorelines affect many parcels. St. Johns River Water Management District jurisdiction governs the county's wetlands and stormwater. Orlando Sanford International Airport and small general-aviation airports impose airspace and noise compatibility zones.

• Wekiva Study Area (WSA) — § 369.318 Florida Statutes and Seminole County LDC overlay — The WSA covers approximately one-third of Seminole County (northern and western county including Heathrow, Wekiva, Longwood, and north-county rural-residential areas). Parcels within the WSA face density caps, water-quality protection requirements (including enhanced septic-system design or mandatory connection to central sewer), and tree-protection and open-space requirements. An ADU on a WSA parcel often requires advanced septic treatment or sewer connection, adding material cost.
• FEMA Special Flood Hazard Areas (SFHA) — Seminole participates in NFIP. Parcels along the St. Johns River (northern county boundary), the Econlockhatchee River, Lake Jesup, Lake Monroe, and tributary corridors face Zone A or AE designations. ADU construction in a mapped floodplain requires elevation-certificate review.
• St. Johns River Water Management District Environmental Resource Permits — Seminole sits within SJRWMD jurisdiction. ADU site work affecting wetlands or altering stormwater requires an ERP. Seminole's mixed-density suburban landscape contains many small wetland features on suburban parcels.
• Hurricane Wind Zone — approximately 130-140 mph ultimate design wind speed — Seminole sits in approximately the 130-140 mph ASCE 7-22 ultimate design wind-speed zone (Risk Category II residential). Inland relative to Atlantic coast but still subject to hurricane construction requirements; Hurricane Ian (2022) produced substantial wind and flood impact in Seminole despite being inland.
• Orlando Sanford International Airport and general-aviation airport zones — Orlando Sanford International Airport (SFB) and smaller general-aviation airports (Orlando Apopka Airport) impose airspace and noise-compatibility zones. Parcels within the mapped noise-compatibility zone face additional review for new residential construction.