Miami-Dade County, FL Accessory Structures: ADU Rules (2026)
ADU rules in Miami-Dade County, FL, also called accessory dwelling unit regulations or granny flat ordinances, cover setbacks, owner-occupancy, parking, and permit requirements.
Key Facts
- Min Lot (RU-1)
- 7,500 sq ft
- ADU Size
- 400-800 sq ft
- Garage Conversion
- 5,000 sq ft lot
- Owner Occupancy
- Required in one unit
- HVHZ
- Hurricane code applies
Summary
Miami-Dade County allows ADUs in AU, EU, and RU districts within the Urban Development Boundary. RU-1 requires minimum 7,500 sq ft lot with 400-800 sq ft ADUs. Garage conversions permitted on 5,000 sq ft lots with 220 sq ft minimum habitable area.
Miami-Dade County has approved an ordinance, allowing an accessory dwelling unit (ADU) or guesthouse in a single-family zoned district either as a newly detached or attached dwelling unit, including the conversion of a portion of an existing single-family dwelling... An ADU is an attached or detached accessory building, or portion thereof, that is used as an ancillary residential unit and is located on the same lot as the principal single-family dwelling. It has a separate kitchen, bathroom, and sleeping area, and it is intended for use by a separate family of occupants.
Full Breakdown
Miami-Dade County permits Accessory Dwelling Units in AU, EU, and RU zoning districts located inside the Urban Development Boundary, and GU districts designated for AU, EU, or RU. For RU-1 districts, the minimum lot size is 7,500 square feet with ADU size between 400 and 800 square feet. Garage conversions have reduced requirements: 5,000 square foot minimum lot and 220 square foot minimum habitable area. ADUs cannot exceed 50% of the primary dwelling's size or 1,200 square feet maximum. Either the main house or ADU must be owner-occupied. One ADU per property is allowed. Maximum one additional parking space required with no more than two vehicles. All construction must comply with HVHZ hurricane building code standards including impact-resistant windows and doors. Building permits cost $1,500-$3,000 with 3-6 month review times.
Violations & Fines
Unpermitted ADU construction results in stop-work orders. Non-compliant structures may require demolition. HVHZ violations require retrofitting. Penalties under Chapter 8CC.
Frequently Asked Questions
Can I build an ADU in Miami-Dade County?
Do ADUs need impact windows in Miami-Dade?
Can I rent out an ADU?
Sources & Official References
Other rules in Miami-Dade County
How Miami-Dade County compares: Easiest Cities to Build an ADU·Florida rules heatmap·Compare Miami-Dade County to another location·View the Florida accessory structures overview
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