Hillsborough County, FL Accessory Structures: ADU Rules (2026)
ADU rules in Hillsborough County, FL, also called accessory dwelling unit regulations or granny flat ordinances, cover setbacks, owner-occupancy, parking, and permit requirements.
Key Facts
- Minimum lot size
- 7,000 square feet
- Standard size cap
- 900 square feet living space
- Variance cap
- 1,200 sq ft on 14,520 sq ft lot
- Citation
- Sec. 6.11.02.A, C, LDC
Summary
Hillsborough County requires accessory dwelling units to sit on a conforming lot of at least 7,000 square feet and caps living space at 900 square feet under the Land Development Code's accessory dwelling standards.
A. The accessory dwelling shall be located on a conforming or legal non-conforming residential lot developed with a detached single-family home. Unless otherwise expressly permitted in a Planned Development, a minimum lot area of 7,000 square feet shall be required.
B. The residential lot shall be occupied by a principal detached single-family dwelling that is owner occupied. These requirements shall not be varied.
C. Living space in the accessory dwelling shall be limited to a maximum of 900 square feet. A variance to increase this amount may be requested provided the residential lot is at least 14,520 square feet in size and the living space proposed for the accessory dwelling does not exceed 1,200 square feet or 25 percent of the living space in the principal dwelling on the lot, whichever is less. For purposes of this regulation, living space shall include all areas within the dwellings utilized for living, sleeping, eating, cooking, bathing, washing, sanitation, laundry and storage purposes. Notwithstanding, living space shall not include motor vehicle garages and attics, provided such areas are not conditioned and are utilized solely for parking and storage purposes, and covered patios as defined by this Code. Living space shall be measured from the outside faces of the exterior walls.
Full Breakdown
Section 6.11.02 of the Land Development Code sets the county's core ADU standards for unincorporated areas. The unit must sit on a conforming or legal non-conforming lot with a detached single-family home, with a minimum 7,000-square-foot lot required unless a Planned Development permits otherwise. Living space is capped at 900 square feet; owners on lots of at least 14,520 square feet may seek a variance up to 1,200 square feet or 25 percent of the principal home, whichever is less. The unit may be attached or detached and must meet the principal dwelling's setbacks and count toward lot coverage.
Violations & Fines
Non-conforming lot size or oversized living area triggers permit denial; owners must obtain a formal variance from the county before building or expanding beyond the 900-square-foot cap.
Frequently Asked Questions
Can I build a bigger ADU than 900 square feet?
Does every lot qualify for an ADU?
Sources & Official References
Other rules in Hillsborough County
How Hillsborough County compares: Easiest Cities to Build an ADU·Florida rules heatmap·Compare Hillsborough County to another location·View the Florida accessory structures overview
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