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ADU construction in Miami typically runs between $106,200 and $259,600 for a complete, turn-key accessory dwelling unit in 2026. Most homeowners in neighborhoods like Coconut Grove, Shenandoah, and The Roads land between $150,000 and $190,000 for a standard 600 to 800 square foot detached unit with a kitchen, bathroom, and separate entrance. The final number depends on square footage, foundation type, finish level, and whether you build detached, attached, or convert an existing garage.
That range is wide for a reason. A 400-square-foot garage conversion with a modest kitchenette and a single bathroom sits near the bottom. A 1,000-square-foot two-bedroom detached ADU with impact windows, a full kitchen with stone counters, and a separate laundry room lands near the top. Either way, you should expect a written number before any work starts, not a ballpark that shifts after the slab is poured.
ADU Construction Cost Breakdown (2026)
Here’s what the numbers actually look like when you break a Miami ADU project into its component parts. These ranges reflect what we see in Dade County in 2026, where materials, labor, and permitting all carry a Miami premium compared to the national average.
| ADU Component | Typical Miami Range |
|---|---|
| Full ADU Construction (turn-key) | $106,200 – $259,600 |
| Garage Conversion (existing slab) | $35,400 – $94,400 |
| Design & Architectural Plans | $4,000 – $12,000 |
| Site Prep & Foundation | $8,000 – $25,000 |
| Framing & Shell | $25,000 – $55,000 |
| Plumbing & Electrical | $15,000 – $35,000 |
| HVAC (mini-split or ducted) | $4,000 – $12,000 |
| Kitchen (cabinets, counters, appliances) | $10,620 – $23,600 |
| Bathroom | $10,620 – $33,040 |
| Impact Windows & Doors | $9,440 – $29,500 |
| Roofing | $9,440 – $23,600 |
| Flooring & Finishes | $6,000 – $18,000 |
| Permits & Impact Fees | $5,000 – $18,000 |
Those permit and impact fee numbers deserve a closer look. Miami-Dade County charges school impact fees, fire assessment fees, and water and sewer connection charges that many homeowners don’t see coming. Depending on the zoning district and whether your property sits in a flood zone requiring elevation, permitting and fees alone can add $15,000 or more before the first wall goes up. We include a permit line item on every written estimate so there are no surprises at the building department counter.
What Affects ADU Construction Pricing in Miami
Every ADU project in Miami carries its own cost profile. Here are the factors that move the number most, in our experience building and remodeling homes across Dade County.
- Flood zone and elevation requirements. If your property sits in an AE flood zone, FEMA elevation requirements can add $20,000 to $40,000 for fill, stem walls, or pilings. Miami-Dade is stricter than most counties in Florida on this, and it’s non-negotiable with the building department.
- Wind load and impact code compliance. Miami requires impact-rated windows, doors, and garage doors, plus strapping and tie-downs rated for 175 mph winds. You’ll spend $9,440 to $29,500 on impact windows alone. Going cheap here means failing the final inspection, no exceptions.
- Detached versus attached versus conversion. A garage conversion uses an existing slab and roofline, which is why it runs $35,400 to $94,400 rather than six figures. A detached unit needs its own foundation, water and sewer lateral connections, and separate electrical service, which all add cost.
- Square footage and layout complexity. Every additional 100 square feet adds roughly $18,000 to $30,000 in Miami once you factor in foundation, framing, roofing, and finishes. A rectangular footprint keeps framing costs down; L-shaped or second-story units push labor hours up.
- Finish level and material choices. Cabinetry ranges from $4,720 for simple stock boxes to $15,340 for semi-custom lines. Countertops range from $2,360 for a basic laminate or tile top to $7,670 for quartz or granite. These choices alone can swing your final number by $15,000 or more.
- Site access and existing conditions. Tight lots in neighborhoods like Little Havana or Allapattah can mean hand-carrying materials, renting a smaller excavator, or removing trees before site prep starts. We’ve seen site access add $5,000 to $8,000 on tight urban lots.
How to Save on ADU Construction
You can’t cut corners on Miami’s building code, and you shouldn’t cut corners on the parts of the project that keep water out and keep the structure standing. But there are real ways to bring the number down without compromising the unit’s safety or resale value.
Convert first, build second. If you have an existing garage with a sound slab and roof structure, converting it will cost roughly a third of building detached. You keep the foundation, shell, and roofline, and put your money into the interior systems and finishes.
Keep the footprint simple. A single-story rectangle with a simple gable roof is the cheapest thing to frame, roof, and waterproof. Every corner, bump-out, and roofline change adds labor hours to the framing, sheathing, and roofing phases.
Choose mid-range finishes. You don’t need Cambria quartz and custom cabinetry to rent the unit for $2,200 a month. Stock or semi-custom cabinets, a solid quartz or butcher-block countertop, and porcelain tile floors will hold up for years without blowing the budget.
Plan the full scope before you start. Change orders are where budgets die. When you have a complete written scope and a written price before the first day of work, you don’t pay for surprises that should have been caught in planning. That’s how we operate, and it’s the main reason our number on day one is the number on the invoice.
If you want a real number for your specific lot and your specific project, call us at (850) 988-7559. The estimate is free, it’s in writing, and it covers everything from the first architectural meeting to the final inspection.
Is ADU Construction Worth It in Miami?
For most homeowners in Miami, an ADU is one of the highest-return investments available in the 2026 market. Here’s the math we walk clients through. Current rental rates for a one-bedroom ADU in neighborhoods like Coral Way, The Roads, and parts of Kendall run $1,800 to $2,600 per month depending on finishes and proximity to downtown. On a $175,000 build, that’s a gross yield of roughly 12% to 18% annually. You’ll recoup your investment in six to nine years at current rates, and that’s before accounting for the property value bump, which appraisers in Dade County typically put at 60% to 80% of the construction cost.
Compare that to a kitchen remodel. A $40,000 kitchen returns roughly $30,000 to $35,000 in resale value. A $175,000 ADU generates rent and adds $105,000 to $140,000 in appraised value. The ADU is the better long-term play for most people who have the lot space and the patience for a four to seven month construction timeline.
ADU Construction Timeline in Miami
A standard detached ADU in Miami takes four to seven months from first design meeting to final certificate of occupancy. Here’s how the timeline breaks down.
- Design and permitting: 6 to 10 weeks. Architectural drawings, zoning review, flood zone confirmation, and building department plan review. Miami-Dade is thorough, and plan review alone can take three to five weeks depending on the season.
- Site prep and foundation: 2 to 4 weeks. Clearing, excavation, formwork, rebar, slab pour, and concrete cure time. In flood zones requiring elevation, add two to three weeks.
- Framing and roof: 3 to 5 weeks. Walls, trusses, sheathing, and roofing. Hurricane-rated strapping and clips add time to this phase compared to other markets.
- Mechanical rough-in: 2 to 3 weeks. Plumbing, electrical, and HVAC rough-in before the drywall goes up.
- Finishes and fixtures: 4 to 6 weeks. Drywall, paint, flooring, cabinetry, countertops, plumbing trim, electrical fixtures, and the kitchen and bath installs.
- Final inspections and punch list: 1 to 2 weeks. Building, electrical, plumbing, and mechanical finals, followed by any corrective work and the certificate of occupancy.
Garage conversions run significantly faster, typically 10 to 14 weeks from permit to occupancy, because the structure already exists. That’s one more reason conversions sit at the bottom of the cost range.
ADU Construction Financing Options
Most Miami homeowners pay for ADU construction using one of three methods: cash from savings or a home equity line, a cash-out refinance, or a construction-to-permanent loan. HELOCs are still the most common because they’re flexible and the interest is typically deductible if the funds are used for the property. Cash-out refinances make sense if you bought before rates rose and have significant equity. Construction-to-permanent loans roll the construction note into a mortgage when the project finishes, which keeps your monthly payment predictable from day one.
Whatever route you take, lenders in Florida generally want a detailed scope of work, a written contract with a licensed contractor, and proof that the contractor carries general liability insurance and workers’ compensation coverage. We provide all three with every project, in writing, before anyone picks up a shovel.
FAQs – ADU Construction Cost
How much does an ADU cost per square foot in Miami?
You should expect to pay between $220 and $350 per square foot for a turn-key ADU in Miami in 2026. A 600-square-foot unit at the midpoint lands around $165,000, while an 800-square-foot unit with mid-range finishes typically comes in between $190,000 and $230,000. Garage conversions run $90 to $160 per square foot because the shell already exists. For an exact per-square-foot number on your lot, call (850) 988-7559 and we’ll put it in writing.
Is it cheaper to convert a garage or build a detached ADU?
A garage conversion costs $35,400 to $94,400 in Miami, while a detached ADU runs $106,200 to $259,600. Converting is almost always cheaper because you skip the foundation, site prep, and half the framing and roofing. The tradeoff is square footage and ceiling height, plus the fact that you lose covered parking. If your garage is already built on a solid slab and the roof is in good shape, conversion is the clear financial winner.
Can I build an ADU in Miami if my property is in a flood zone?
Yes, but it will cost $20,000 to $40,000 more than the same build on higher ground. Miami-Dade requires elevation above the base flood elevation in AE zones, which means fill, stem walls, or raised foundations. You’ll also need a flood elevation certificate and a surveyor’s stamp on the plans. We navigate this weekly in neighborhoods like Allapattah, Grapeland Heights, and parts of Shenandoah, and we include the elevation cost in your written estimate before you commit.
How long does ADU construction take in Miami?
Plan for four to seven months for a detached ADU and 10 to 14 weeks for a garage conversion. The biggest variable is permitting: Miami-Dade plan review runs three to five weeks, and flood zone or zoning variance requests can stretch that to eight or ten. Once construction starts, weather is the wild card. Summer afternoon storms routinely shut down exterior phases for a day or two at a time.
What permits do I need for an ADU in Miami?
You need a building permit, electrical permit, plumbing permit, mechanical (HVAC) permit, and a zoning approval, at minimum. Depending on your property you may also need a tree removal permit, a right-of-way permit for sewer or water lateral work, and a flood elevation certificate. Permit fees and impact fees for a standard ADU in Miami run $5,000 to $18,000. We handle the full permit package as part of every project and it’s always listed as a line item in your written price.
Does an ADU add value to a Miami home?
Appraisers in Miami-Dade typically credit an ADU at 60% to 80% of its construction cost in added property value. A $175,000 unit usually adds $105,000 to $140,000 in appraised value, plus rental income of $1,800 to $2,600 per month at current 2026 rates. That combination of equity and cash flow is why ADUs have become the most requested project we quote in Miami.
Why the Written Price Matters More Than the Number Itself
Every contractor in Miami can tell you a number. The difference is what happens to that number after the slab is poured and the first wall is framed. The Kingswell Way, which we’ve operated under since 2004, is built around putting the price in writing before any work starts. Not an estimate range. Not a verbal ballpark. A written number you can hold us to, with a defined arrival window and a written guarantee on every project.
That guarantee is the 365-Day Done Right Promise. Here’s what it means in plain terms: if the work fails inside the guarantee period, we come back and fix it at no charge. No re-inspection fee, no service call charge, no negotiation. It’s written into every contract. And if a repair fails after we’ve been to your home, the second visit is free, period. That promise works because we install materials worth backing. We build ADU kitchens with KraftMaid or Wellborn cabinetry and Cambria or Silestone countertops, and we use Kohler or Moen fixtures in the bathrooms. These brands carry their own warranties alongside ours, which means your ADU is protected by two layers of written protection.
Trevor Nash runs Penhallow Remodeling Miami, and he’s the person who reviews every written estimate before it reaches your hands. You’ll also deal with background-checked, uniformed technicians on every visit, and you’ll always reach a live person when you call, day or night. That’s a standard operating practice here, not a marketing bullet.
Get Your ADU Price in Writing
If you’re considering an ADU in Miami and you want a real number for your specific lot, your specific square footage, and your specific finish level, call us. You’ll talk to a person, not a voicemail prompt. We’ll schedule a site visit, walk the property with you, and hand you a written price that covers design, permits, construction, and finishes. The number on that page is the number on your invoice at the end of the project.
Call (850) 988-7559 to schedule your free ADU estimate. We serve homeowners across Miami, from Coconut Grove and Coral Way to Shenandoah, Allapattah, and Kendall. You can also explore our ADU Construction in Miami page for more detail on what we build, or return to our home page to see the full range of remodeling services we offer.
Pricing reflects the Miami market as of 2026. Penhallow Remodeling Miami offers free estimates – call (850) 988-7559.
Written by Trevor Nash, Owner at Penhallow Remodeling Miami, serving Miami since 2004.
What Our Customers Say
"Full home refresh before we sold. They were straight about what was worth doing and what wasn't to get our money back. On time, on budget, and it sold in a week."
- Monica Vaughn"Full kitchen down to the studs. The written estimate held and they finished on the day they promised. Crew was tidy and polite the whole month. Rare to find."
- Vernon Askew"Did our whole kitchen. The written estimate held, which after reading remodel nightmares online I did not take for granted. Showed up every morning on time and the crew was clean and polite."
- Warren Updike
