Seminole County ADU Rules (2026)
Seminole County, Florida ADU ordinance, permit process, and typical fees and timelines.
Seminole County ADU Rules (2026) — quick facts
- Lot drawn
- R-1AA minimum lot 7,500 sq ft for a detached ADU
- ADU footprint
- drawn at the 1,000 sq ft cap
- Side setback
- 7.5 ft
- Rear setback
- 10 ft
- Front setback
- match primary
- Height
- Shall not exceed the primary dwelling; 22 ft in single-story zones
- Size rule
- 1,000 sq ft or 35% of the primary structure's gross floor area, whichever is less.
- R-1A lots: 6,000 sq ft minimum. Not drawn.
- Parking: 1 additional off-street space.
Source: Seminole County Land Development Code (accessory dwelling units). Schematic, not a survey. Confirm your district and setbacks with the county before designing.
Detailed rules
| Max ADU size | 1,000 sq ft OR 35% of gross floor area of primary structure, whichever is less |
|---|---|
| Min lot size | 7,500 sq ft for detached ADUs in R-1AA; 6,000 sq ft in R-1A |
| Setbacks | Rear: 10 ft; Side: 7.5 ft; Front: match primary |
| Parking | 1 additional off-street space |
Permit process
| Permit office | Seminole County Development Services |
|---|---|
| Phone | (407) 665-7371 |
| Online portal | https://www.seminolecountyfl.gov/departments-services/development-services/ |
| Typical timeline | 10–16 weeks |
| Typical fees | $2,000–$3,800 total for a 600 sq ft ADU |
Cities in Seminole County ADU Rules (2026)
Incorporated cities may have rules that differ from the county. Click a linked city for its specific ordinance.
In unincorporated Seminole County an ADU may be 1,000 sq ft or 35% of the primary structure’s gross floor area, whichever is less. On a 2,000 sq ft house that is 700 sq ft, not 1,000, and it is the number homeowners here most often get wrong when they sketch a plan before reading the code. The county’s Land Development Code permits what it calls “accessory dwelling units” in most single-family residential districts, with owner-occupancy required and one additional off-street parking space. Seminole sits north of Orange County and includes Sanford, Altamonte Springs, Lake Mary, Oviedo, Winter Springs, Longwood, and Casselberry; the cities listed below have their own rules, and the county LDC covers everything else.
Planning staff briefed the Board of County Commissioners on state preemption in March 2026, expecting SB 48 to pass. It did not; the session ended without a House vote, so there is no state compliance deadline and the LDC above is still the whole rulebook. (The Florida ADU law page has the statewide picture.)
Incorporated cities in Seminole County with their own ADU rules:
- Oviedo ADU Rules (2026): new 2024 LDC with dedicated ADU section; 1,000 sq ft / 50% size cap; no owner-occupancy requirement
- Sanford ADU Rules (2026): county seat on Lake Monroe; three National Register historic districts with HPB Certificate of Appropriateness review; verify specific dimensional standards with Planning before designing
Permit process specifics
Seminole’s permit office is colocated with Development Services at 1101 E 1st St in Sanford. Typical timeline from a complete application to final inspection is 10–16 weeks, longer than Orange County’s typical throughput but with a reputation for clearer plan review comments and fewer back-and-forth cycles. Expect $2,000–$3,800 in total fees for a 600 sq ft ADU, including impact fees.