Zoning & Size Limits
| Requirement | Miami, FL | Jacksonville, FL |
|---|
| Allowed Zones | City of Miami: ADUs allowed in T3-L under Miami 21; a propos | Select residential 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) | 25% of primary residence or 750 sq ft (whichever is smaller) |
| Max Size (Attached) | See max_size_detached — confirm with City of Miami Planning | 25% of primary residence or 750 sq ft (whichever is smaller) |
| Max Height | Must not exceed height of principal structure | Must not exceed height of primary residence |
| Parking Required | Maximum 1 additional space (no more than 2 vehicles); must b | 1 space |
| Owner Occupancy | Effectively required for rental: an ADU may be rented only i | Required — owner must occupy either the primary residence or |
Setback Requirements
| Setback | Miami, FL | Jacksonville, FL |
|---|
| Rear Setback | 5 ft (RU-1 district) | 20 feet |
| Side Setback | 5 feet | 5 feet |
| Front Setback | 25 feet | 25 feet |
Permits & Timeline
| Detail | Miami, FL | Jacksonville, FL |
|---|
| Permit Timeline | 120-180 days | 80-110 days |
| Permit Fees | $5,000-$8,000 | $3,200-$5,000 |
| Impact Fees | $2,000-$3,500 | $1,300-$2,000 |
| Pre-Approved Plans | Yes — Miami-Dade County ADU Blueprint program offe | Not available |
Construction Costs
| Cost | Miami, FL | Jacksonville, FL |
|---|
| Avg Build Cost | $180,000-$350,000 | $125,000-$245,000 |
| Cost Per Sq Ft | $240-$460 | $155-$305 |
| Garage Conversion | $80,000-$180,000 | $60,000-$145,000 |
| Prefab ADU | $120,000-$260,000 | $90,000-$210,000 |
Rental Income Potential
| Rental | Miami, FL | Jacksonville, FL |
|---|
| 1BR Avg Rent | $1,600-$2,200/mo | $1,100-$1,600/mo |
| 2BR Avg Rent | $2,000-$3,000/mo | $1,400-$2,000/mo |
| Short-Term Rentals | Not permitted | Varies by district |
| Est. ROI | 5-7% annual return | 6-8% annual return |
Which City Is Better for ADUs?
Miami scores 5/10 while Jacksonville scores 5/10 on our ADU-friendliness index.
Both cities offer viable ADU development opportunities — the best choice depends on your specific property, budget, and goals.
Finance Your ADU Project
Most ADU projects are funded through HELOCs, construction loans, or cash-out refinancing. Compare rates from top lenders.
Some links on this page are affiliate links. We may earn a commission at no extra cost to you. Learn more
Get Quotes in Your City
Connect with licensed ADU contractors and get free quotes for your project.