Seminole County ADU Rules (2026)

Seminole County, Florida ADU ordinance, permit process, and typical fees and timelines.

By Andy West

Seminole County ADU Rules (2026) — quick facts

Maximum ADU size
1,000 sq ft OR 35% of gross floor area of primary structure, whichever is less
Minimum lot size
7,500 sq ft for detached ADUs in R-1AA; 6,000 sq ft in R-1A
Short-term rental allowed?
No — 30-day minimum typical
Owner-occupancy required?
Yes
Current ordinance status
Existing LDC governs; no pending amendments
Typical permit timeline
10–16 weeks

Detailed rules

Size and lot requirements

  • 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.

  • Sanford
  • Altamonte Springs
  • Lake Mary
  • Oviedo
  • Winter Springs
  • Longwood
  • Casselberry

Seminole County sits north of Orange County and includes Sanford, Altamonte Springs, Lake Mary, Oviedo, Winter Springs, Longwood, and Casselberry. The county’s Land Development Code permits what it calls “accessory dwelling units” in most single-family residential districts, subject to size limits and owner-occupancy requirements. These are the operative rules.

Planning staff briefed the Board of County Commissioners on state ADU preemption in March 2026 in anticipation of SB 48, but SB 48 did not become law. It died when the 2026 session ended without a House vote. There is no state compliance deadline, and Seminole’s existing LDC remains in effect unchanged. For the statewide picture, see the Florida ADU law pillar (or in Spanish); for the legislative record, see the SB 48 post-mortem.

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.

Deed-restricted communities in Seminole, particularly in Oviedo and Winter Springs, are the most common reason ADU plans do not proceed. Check your covenants first.

Primary sources