Valrico

Hillsborough County regulates accessory dwelling units on unincorporated parcels through the Hillsborough County Land Development Code (LDC), administered by Hillsborough County Development Services. The county includes the Tampa urban core (separately incorporated), the incorporated cities of Temple Terrace and Plant City, and a very large unincorporated territory that ranges from dense urban neighborhoods (Brandon, Town 'n' Country, Carrollwood, Citrus Park, University, Greater Sun City Center) to rural eastern and southern agricultural tracts. § 163.31771 FS is permissive only. Hillsborough's ADU rules arise entirely from local zoning, and the City of Tampa's active ADU ordinance (adopted 2020) governs parcels inside Tampa city limits — a materially different framework than the county's.

• Hillsborough County Land Development Code
• Florida Statutes § 163.31771 — Accessory Dwelling Units

State-floor overlay: No Florida statewide ADU preemption floor exists as of April 2026. SB 48 / HB 313 (2026 session) is the active preemption bill. Hillsborough retains full discretion until enactment.

Hillsborough County administers flood, coastal-high-hazard, airport-approach, and wellhead-protection overlays that cut across jurisdictions. Tampa Bay and three major river systems (Hillsborough, Alafia, Little Manatee) produce extensive AE-zone coverage, and the Tampa International Airport approach zones constrain height across much of the western half of the county.

• FEMA Special Flood Hazard Areas (SFHA) — AE- and VE-zone mapping is extensive along Tampa Bay, the Hillsborough River, the Alafia River, the Little Manatee River, and associated tributaries. ADUs in SFHA require elevation above BFE plus county freeboard, flood vents, and flood-resistant materials. VE-zone exposure on Tampa Bay produces pile-foundation or breakaway-wall requirements on affected parcels.
• Coastal High Hazard Area (CHHA) — Under state law, the CHHA is the area below the elevation of the Category 1 storm surge line as defined by the SLOSH model. Hillsborough's CHHA covers substantial portions of the Tampa Bay shoreline and limits certain intensification of residential development; ADUs in CHHA face heightened review under the Coastal Element of the comprehensive plan.
• Tampa International Airport (TPA) Approach & Height Zoning — Parcels within TPA approach and transitional surfaces face height limitations. A two-story ADU may require FAA Form 7460 notice on high-exposure parcels; the practical effect on one-story accessory units is limited.
• Southwest Florida Water Management District (SWFWMD) Wellhead Protection — Hillsborough parcels within mapped wellhead-protection zones face enhanced septic-siting review. Many unincorporated eastern Hillsborough parcels are on private septic and are affected.
• MacDill Air Force Base Accident Potential & Noise Zones — South Tampa parcels near MacDill AFB fall within Air Installation Compatible Use Zones (AICUZ) with accident-potential and noise-attenuation requirements. New residential construction — including ADUs — in designated APZ areas is restricted; parcels in the noise-attenuation zone require sound-insulating construction.
• Wildland-Urban Interface (WUI) — Practical WUI exposure in urbanized western Hillsborough is low. Eastern Hillsborough rural tracts abutting undeveloped pine flatwoods are higher-hazard; enforcement intensity is still maturing.

Permits for ADUs on unincorporated Hillsborough County parcels are issued by Hillsborough County Development Services, which combines zoning, building, and floodplain review under one intake. Unincorporated Hillsborough is the second-largest unincorporated population in Florida and includes many dense suburban communities that operate de facto like cities. Incorporated municipalities (Tampa, Temple Terrace, Plant City) handle their own permits.