Miami's ADU regulations are relatively restrictive due to density concerns and hurricane/flood resilience requirements. However, the city recently began exploring ADU policies to address housing affordability. ADUs are allowed in select zones with significant restrictions.
Zoning & Size Requirements [1][2][3]
Yes, you can build an ADU in Miami. A detached ADU can be up to 800 sq ft under current Florida and Miami zoning rules.
| Allowed Zones | City of Miami: ADUs allowed in T3-L under Miami 21; a proposed expansion to T3-R/T3-O passed first reading Feb 2025 — confirm adoption status with City of Miami Planning. (Unincorporated Miami-Dade County allows ADUs in AU/EU/RU/GU districts.) |
| Max Size (Detached) | City of Miami: confirm current cap with City of Miami Planning (proposed ~500 sq ft / 10% of lot, capped at 800 sq ft). Unincorporated Miami-Dade: 400-800 sq ft in RU-1 districts (varies by district) |
| Max Size (Attached) | See max_size_detached — confirm with City of Miami Planning |
| Max Size (JADU) | Not allowed |
| Max Height | Must not exceed height of principal structure |
| Max Units | 1 ADU per lot |
Setback Requirements [1][2][3]
Miami requires a rear setback of about 5 ft for a detached ADU, and one off-street parking space is required. Owner-occupancy is set by local rules (confirm with the city).
| Rear Setback | 5 ft (RU-1 district) |
| Side Setback | 5 feet |
| Front Setback | 25 feet |
| Parking Required | Maximum 1 additional space (no more than 2 vehicles); must be on-site or in adjacent swale (Miami-Dade County) |
| Owner Occupancy | Effectively required for rental: an ADU may be rented only if the primary residence is owner-occupied (homestead); same ownership required for both units. Unincorporated Miami-Dade County requires the owner to occupy the principal dwelling (the owner cannot live in the ADU). |
| Min Lot Size | 7,500 sq ft (Miami-Dade County minimum for ADUs) |
Permit Process & Fees [4]
An ADU permit in Miami typically costs $5,000-$8,000 and takes 120-180 days, through a ministerial, by-right review.
| Approval Process | By-right / administrative site-plan review + building permit in qualifying districts (a zoning variance is only needed for nonconforming or undersized lots) |
| Review Timeline | 120-180 days |
| Permit Fees | $5,000-$8,000 |
| Impact Fees | $2,000-$3,500 |
| Plan Check | 6-8 weeks |
| Pre-Approved Plans | Yes — Miami-Dade County ADU Blueprint program offers pre-approved designs for faster permitting |
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Construction Costs [5][6]
Building an ADU in Miami typically costs $180,000-$350,000 ($240-$460 per sq ft); a garage conversion runs $80,000-$180,000.
| Average Build Cost | $180,000-$350,000 |
| Cost per Sq Ft | $240-$460 |
| Garage Conversion | $80,000-$180,000 |
| Prefab ADU (Installed) | $120,000-$260,000 |
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Rental Income Potential [7][8]
A 2-bedroom ADU in Miami rents for around $2,000-$3,000/mo, an estimated 5-7% annual return.
| Avg Rent (1 Bedroom) | $1,600-$2,200/mo |
| Avg Rent (2 Bedroom) | $2,000-$3,000/mo |
| Short-Term Rental | Not permitted |
| Est. Annual ROI | 5-7% annual return |
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Recent Law Changes
What's Changed Recently
- Florida SB 48 (2026 session): a statewide ADU mandate passed the Senate 38-0 on Feb 4, 2026 but died in House Messages on Mar 13, 2026 without a House floor vote - local rules still govern; reform is widely expected to return in 2027
- Miami-Dade County ADU Blueprint program is live: offers pre-approved ADU designs and requires an annually renewed Certificate of Use (obtainable only by the property owner) for all ADUs
- City of Miami: ordinance to expand ADUs from T3-L to T3-R/T3-O zones passed first reading Feb 2025; final adoption status should be confirmed with City of Miami Planning
- Miami-Dade County requires owner-occupancy of one unit as a principal residence; fully absentee-owned properties do not qualify for an ADU permit
Tips for Building an ADU in Miami
- Miami requires extensive flood mitigation; elevated construction adds significant cost
- Hurricane-resistant design standards are mandatory; budget for reinforcement
- Salt-air corrosion requires premium materials; factor into long-term costs
- Zoning variance process is lengthy; engage planning consultants early
ADU Builders in Miami
Looking for an ADU builder in Miami? ADU projects need a contractor experienced with local zoning, the permit process, and utility connections — not every general contractor has built one. We match Miami homeowners with experienced local ADU contractors who provide free, no-obligation quotes. Getting at least three bids typically saves 20-40% on the same scope.
Sources & References
All data on this page is sourced from official government records and verified market data. View our full methodology.
- Accessory Dwelling Unit (ADU) — Miami-Dade County Planning Department — Accessed 2026-06-28
- ADU Blueprint for Homeowners — Miami-Dade County Planning Department — Accessed 2026-06-28
- Miami 21 Zoning Code | City of Miami Municipal Code — Accessed 2026-06-28
- City of Miami Code of Ordinances (Municode) Municipal Code — Accessed 2026-02-24
- Angi — ADU Construction Cost Data Market Data — Accessed 2026-02-24
- Angi — Local ADU Contractor Costs Market Data — Accessed 2026-02-24
- Zillow Rental Manager — Market Rent Data Market Data — Accessed 2026-02-24
- HUD Fair Market Rents Government Data — Accessed 2026-02-24
- Planning & Zoning | City of Miami Planning Department — Accessed 2026-02-24
- Florida Live Local Act — ADU Provisions Government Data — Accessed 2026-02-24
Frequently Asked Questions
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