Complete 2026 cost breakdown: construction, permits, financing, and expected rental ROI.
Calculate your Miami ADU cost →Building an ADU in Miami costs between $150,000-$320,000 for new construction, with per-square-foot costs averaging $250-$450. These figures include design, permitting, site preparation, and construction. The most affordable option is a garage conversion at $80,000-$160,000, while prefab/modular ADUs fall in between at $130,000-$250,000.
| Cost Category | Estimated Range |
|---|---|
| Architectural Plans | $3,000 – $15,000 |
| Permits & Fees | About $2,200-$3,500 in city building fees on a $200,000-$350,000 unit: 0.50% of construction cost (min $110), $2.80 per $1,000 up-front, solid-waste $0.22 per $100 (max $600), energy $0.11/sq ft, CO $105 (Res. R-26-0200, 4/23/2026); zoning $250 up-front; impact fees extra. |
| Impact Fees | City impact fees (City Code Ch. 13) plus Miami-Dade County mobility and school fees. The County's 2024-2027 rate sheet lists single-family detached at $9,275-$10,625 (mobility) plus $612 per unit and $0.918 per sq ft (school); the sheet has no ADU line, so request a written estimate before you design. |
| Site Prep & Foundation | $10,000 – $35,000 |
| Framing & Structure | $15,000 – $45,000 |
| Plumbing | $8,000 – $20,000 |
| Electrical | $5,000 – $15,000 |
| HVAC | $3,000 – $8,000 |
| Interior Finishes | $15,000 – $40,000 |
Quotes for the same ADU commonly vary 20–40% between builders. We pass your request to up to 5 local builders serving Miami, where we have them — free, no obligation.
Get Miami builder quotes →Permit fees in Miami are About $2,200-$3,500 in city building fees on a $200,000-$350,000 unit: 0.50% of construction cost (min $110), $2.80 per $1,000 up-front, solid-waste $0.22 per $100 (max $600), energy $0.11/sq ft, CO $105 (Res. R-26-0200, 4/23/2026); zoning $250 up-front; impact fees extra.. The review timeline is Not published by the City. Florida Statute 553.792 gives the City 30 business days to review a complete residential application per cycle; plan on 3-6 months from submittal to permit including re-reviews and Miami-Dade County sign-offs., with plan check: Not published; F.S. 553.792 sets a 30-business-day clock per review cycle, and re-reviews after the second cycle cost $56 per discipline. Impact fees are City impact fees (City Code Ch. 13) plus Miami-Dade County mobility and school fees. The County's 2024-2027 rate sheet lists single-family detached at $9,275-$10,625 (mobility) plus $612 per unit and $0.918 per sq ft (school); the sheet has no ADU line, so request a written estimate before you design.. Pre-approved plans: No City of Miami program. Miami-Dade County's ADU Blueprint plans are pre-approved by the County Building Department for unincorporated-area permits; City of Miami permits are reviewed by the City's own Building Department..
| 1-Bedroom Rent | $2,100-$2,500/month |
| 2-Bedroom Rent | $2,500-$3,000/month |
| Annual Rental Income (est.) | $27,600/year |
| Payback Period (est.) | 8.5 years |
| Short-Term Rental | Not permitted: Sec. 3.18 requires the ADU to be used predominantly as permanent housing, and it may be rented only while the property has homestead status |
| Overall ROI Estimate | 6-8% net annual return |
A typical ADU in Miami generates approximately $27,600 per year in rental income based on average 1-bedroom rents. At an average construction cost of $235,000, the estimated payback period is 8.5 years — before accounting for the resale value the ADU adds, which an appraiser determines from comparable sales in Miami and varies by market (often less than build cost).
1. Garage conversions save 40-60% vs new construction since the shell already exists. Average cost in Miami: $80,000-$160,000.
2. Prefab/modular ADUs offer predictable pricing and faster timelines. Average: $130,000-$250,000.
3. Pre-approved plans — Miami does not offer a pre-approved/standard ADU plan program yet, so budget for custom architectural plans (typically $3,000-$15,000). See which cities offer pre-approved ADU plans.
4. State grants — California's CalHFA ADU grant (up to $40K) is currently paused; check calhfa.ca.gov/adu for status and your state for active programs.
5. Get multiple bids — ADU contractor pricing varies 20-40% for the same project. We recommend getting at least 3 quotes.
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