Miami's Accessory Structures: The Rules That Matter

Every city handles accessory structures a little differently. In Miami, Florida, there are 9 distinct rules that residents and property owners should be aware of. Some are stricter than what neighboring cities enforce, and others are more relaxed. Here is what you need to know.

Tiny Homes

Miami regulates tiny homes as accessory dwelling units or primary structures depending on size and lot placement. Tiny homes on foundations must meet Florida Building Code HVHZ standards. Tiny homes on wheels are classified as recreational vehicles with separate parking restrictions.

Key details: On Foundation: Treated as ADU, permit required. ADU Size: 400-1,200 sq ft, max 50% of main. On Wheels: Classified as RV, restrictions apply. Min Lot Size: 7,500 sq ft for ADU. Wind Code: HVHZ standards required.

Unpermitted tiny home construction faces stop-work orders and fines. Using a THOW as a permanent residence in a residential zone violates zoning code. Fines start at $250 per day of violation.

Carport Rules

Miami requires building permits for carport construction. Carports must comply with Florida Building Code wind load requirements, zoning setbacks, and lot coverage limits. The high-velocity hurricane zone standards add additional structural requirements.

Key details: Permit Required: Yes, building permit needed. Wind Zone: HVHZ, up to 175 mph design. Plans: PE or architect stamp required. Setbacks: Must meet zoning requirements. Building Dept: (305) 416-1100.

Unpermitted carports face stop-work orders, fines up to $500 per day, and mandatory removal or retroactive engineering certification. Non-HVHZ-compliant structures must be demolished or retrofitted.

ADU Permits

Miami permits accessory dwelling units in most transect zones under Miami 21, the city's form-based zoning code. Permits are issued by the City of Miami Building Department after Planning and Zoning review under Article 4 (Standards and Tables). Florida HB 1031 (effective July 2024) requires local governments to allow ADUs in single-family zones.

Key details: Code: Miami 21 Article 4 Table 4. State Law: FL HB 1031 (2024); §163.31771. Allowed Zones: T3-R, T3-L, T3-O, T4, T5. Permit Agency: City of Miami Building Dept. Flood Compliance: FBC §1612 elevation.

Constructing an ADU without permits: Code Enforcement Notice of Violation with daily fines, lien, mandatory removal or permit-after-the-fact (with double fees). Building below the BFE in a flood zone: order to elevate or floodproof at owner's expense.

ADU Rental Restrictions

ADUs rented long-term (30+ days) in Miami face no zoning-based restrictions. Short-term rentals (under 30 days) are sharply restricted: in T3 single-family transect zones, City of Miami STR ordinance §2-1100 prohibits non-owner-occupied vacation rentals. Florida Statute §509.032(7) preempts local STR licensing but allows registration.

Key details: Long-Term: Permitted, no city license. STR in T3: Only if owner's primary residence. STR in T4/T5/T6: Allowed with CU. State Preemption: FL §509.032(7). Tourist Tax: 3% + 1% + 6% state = 10% total.

Operating an STR in a T3 zone without primary-residence status: code enforcement fine starting at $500/day, escalating. Operating in T4/T5/T6 without a Certificate of Use: $500 per occurrence. Failure to collect Tourist Development Tax: County Tax Collector enforcement plus state Department of Revenue penalties.

ADU Owner Occupancy

Miami 21 does not require the property owner to live on-site to operate an ADU. Florida HB 1031 (2024) further restricts local governments from imposing owner-occupancy mandates on accessory dwelling units. Recorded deed restrictions in some HOAs may still impose private occupancy rules.

Key details: City Requirement: None. State Preemption: FL §163.31771 (HB 1031). Homestead Risk: Lost if owner moves out. HOA Authority: Private rules permitted. Source of Income: Protected (MDC §11A-26).

City-level: none for owner-occupancy. Homestead loss: tax assessor backbills lost exemption with penalties. HOA: private fines per declaration. Source-of-income discrimination: county human rights enforcement.

The rules around adu owner occupancy in Miami lean permissive, but that does not mean anything goes.

ADU Impact Fees

Miami ADUs are subject to Miami-Dade County impact fees (roads, schools, parks, police, fire) tied to the new dwelling unit, plus City of Miami building permit and plan-review fees. The County's impact fee schedule is set in Miami-Dade Code Chapter 33E. Florida law caps annual increases to county impact fees.

Key details: County Code: Miami-Dade Ch. 33E. State Authority: FL §163.31801. Fee Categories: Roads, schools, parks, police, fire. Annual Cap: Inflation-adjusted (per §163.31801(6)). City Fees: Permit + plan review (Ch. 10).

Building permit will not be issued without proof of impact fee payment. Construction without permits exposes the project to permit-after-the-fact at double fees, and the County may file a lien for unpaid impact fees against the parcel.

Garage Conversions

Garage conversions to ADUs in the City of Miami require building permits and HVHZ compliance. Miami 21 governs ADU eligibility by transect zone. Impact-resistant openings mandatory. Licensed contractors required.

Key details: Permit: Required. HVHZ: Impact windows required. Zoning: Miami 21 transect. Contractor: Licensed required. Owner Occupied: Required for ADU.

Unpermitted conversions result in stop-work orders. Non-HVHZ compliance requires retrofitting. Unlicensed contractor work is a state violation.

ADU Rules

The City of Miami allows ADUs in T3-L transect zones under Miami 21 with maximum 450 sq ft. Owner occupancy required (homestead exemption). Proposed expansions to T3-R and T3-O zones. One ADU per property.

Key details: Zones: T3-L (expanding). Max Size: 450 sq ft. Owner Occupied: Homestead required. Parking: 1 space (TOD exempt). HVHZ: Hurricane code applies.

Unpermitted ADUs require retroactive permitting or removal. Non-owner-occupied units violate homestead requirement. HVHZ non-compliance requires retrofitting.

Shed Rules

Utility sheds in the City of Miami follow Miami-Dade Section 33-20(k): one shed up to 400 sq ft per lot. Sheds under 100 sq ft have reduced setbacks. All sheds must meet HVHZ wind load and anchoring requirements.

Key details: Max Size: 400 sq ft. Limit: One per lot. Side/Rear: 5 ft (2 ft with consent). HVHZ: Anchoring required. Code: §33-20(k).

Unpermitted sheds must be retroactively permitted or removed. HVHZ non-compliance requires anchoring retrofits.

The Bottom Line

Miami's accessory structures rules are a mixed bag. Some areas are strict, others are relaxed, and the details matter. The best approach is to check the specific rule that applies to your situation rather than assuming Miami is broadly strict or permissive.

These rules come from Miami's publicly available municipal code. For complete penalty schedules, exemption details, and answers to common questions, see the individual ordinance pages throughout this guide.