Everything homeowners ask about building an ADU in Miami — answered with 2026 data.
Yes, ADUs are allowed in 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.) in Miami, FL. The maximum size for a detached ADU is 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). Attached ADUs can be up to See max_size_detached — confirm with City of Miami Planning. Miami has an ADU-friendliness score of 5/10. Check our full Miami ADU rules page for complete zoning details.
ADU construction in Miami typically costs $180,000-$350,000. The cost per square foot averages $240-$460. Garage conversions are more affordable at $80,000-$180,000, while prefab ADUs cost $120,000-$260,000. Permit fees add $5,000-$8,000 to your budget. See our detailed Miami ADU cost guide.
Detached ADUs in Miami can be up to 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). Attached ADUs are limited to See max_size_detached — confirm with City of Miami Planning. Junior ADUs (JADUs) have a cap of Not allowed. Maximum height is Must not exceed height of principal structure. You are allowed up to 1 ADU per lot on a qualifying lot.
Rear setback: 5 ft (RU-1 district). Side setback: 5 feet. Front setback: 25 feet. Note that garage conversions may be exempt from setback requirements if the existing structure is already within the setback area.
Maximum 1 additional space (no more than 2 vehicles); must be on-site or in adjacent swale (Miami-Dade County). Many cities and states have been relaxing ADU parking requirements in recent years. In California, no additional parking is required for ADUs near transit.
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).. Note that owner-occupancy rules vary by state law — California and several other states have eliminated this requirement for standard ADUs.
The ADU permit review timeline in Miami is typically 120-180 days. Plan check: 6-8 weeks. Pre-approved plans availability: Yes — Miami-Dade County ADU Blueprint program offers pre-approved designs for faster permitting.
Average ADU rental income in Miami: 1-bedroom units rent for $1,600-$2,200/month, 2-bedroom units for $2,000-$3,000/month. Short-term rentals: Not permitted. Expected ROI: 5-7% annual return.
The minimum lot size for an ADU in Miami is 7,500 sq ft (Miami-Dade County minimum for ADUs). This applies to detached ADUs — garage conversions and JADUs may have different or no lot size requirements.
Garage conversions are one of the most popular and affordable ADU options. In Miami, a garage conversion typically costs $80,000-$180,000. The key advantages are lower cost (no foundation work), potential setback exemptions, and faster permitting. Read our complete garage conversion guide.