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AfterHow Much Does ADU Construction Cost in Miami?
ADU construction in Miami typically costs between $106,200 and $259,600 in 2026, with most homeowners landing around $165,000 to $185,000 for a standard one-bedroom accessory dwelling unit of roughly 600 to 700 square feet. The final number depends heavily on whether you build a detached unit in the backyard, convert an existing garage, or add an attached suite to your home. We’ll walk through exactly what drives that price in the sections below.
If you want a precise number for your property in Coconut Grove, Coral Gables, or Kendall, call (850) 780-8123. We’ll give you a written price before any work starts, and the estimate is free.
ADU Construction Cost Breakdown (2026)
Here’s what an ADU in Miami actually costs, line by line. These ranges reflect what we see across Miami-Dade County in 2026, from permits to final paint.
| Cost Component | Typical Range (Miami, FL) |
|---|---|
| Site preparation & grading | $4,700 – $11,800 |
| Foundation (slab or pier) | $9,400 – $23,600 |
| Framing (walls, roof structure) | $23,600 – $47,200 |
| Roofing (shingle or metal) | $8,260 – $21,240 |
| Plumbing rough-in & fixtures | $9,440 – $21,240 |
| Electrical rough-in, panel, fixtures | $8,260 – $18,880 |
| HVAC (mini-split or ducted) | $5,900 – $14,160 |
| Insulation & drywall | $5,310 – $12,980 |
| Flooring | $3,540 – $10,620 |
| Kitchenette (cabinets, counters, sink) | $7,080 – $21,240 |
| Bathroom (shower, vanity, toilet) | $8,260 – $18,880 |
| Windows & exterior doors | $4,720 – $14,160 |
| Permits, impact fees, architectural drawings | $5,310 – $15,340 |
| Paint, trim, final finishes | $2,360 – $8,260 |
Those line items add up to the $106,200 to $259,600 total range. A garage conversion in Miami tends to run lower because the shell already exists: we typically see $35,400 to $94,400 for that route. A detached ADU with a full kitchen and bathroom sits at the higher end.
Three things move the needle more than anything else in Miami. First is whether you need to lift the structure to meet FEMA flood elevation requirements, which is common in low-lying neighborhoods like Shenandoah or parts of Little Havana and can add $15,000 to $40,000. Second is soil condition: some areas west of the Palmetto sit on limestone that requires specialized excavation. Third is the finish level: IKEA-grade cabinets versus custom millwork can swing the interior budget by $10,000 or more.
What Affects ADU Construction Pricing in Miami
Miami doesn’t build like other cities. Here are the factors that genuinely move your ADU budget:
- Flood zone and elevation requirements. If your lot in Brickell, the Roads, or along the Miami River sits in an AE flood zone, the building may need to be elevated or designed with flood vents and breakaway walls. That’s a real cost, not a line-item afterthought.
- Permitting and impact fees. Miami-Dade charges school impact fees, water and sewer connection fees, and building permit fees based on square footage. For a 600-square-foot ADU, expect $5,000 to $12,000 before you ever break ground.
- Detached versus attached versus garage conversion. A detached unit needs its own foundation, roof, and utility trenching. A garage conversion often reuses the slab, roof, and exterior walls, which is why it costs roughly a third to half as much.
- Utility connections. Running new water, sewer, and electrical lines from the main house or the street can add $6,000 to $18,000 depending on the distance. Older neighborhoods in Coconut Grove with mature tree roots and aging clay pipes push that number higher.
- Hurricane code compliance. Miami-Dade has some of the strictest wind-load standards in the country. Impact-rated windows, reinforced garage doors, and roof straps are required, not optional. That’s built into the numbers above, but it’s why a Miami ADU costs more per square foot than one in Orlando or Tampa.
- Finish level. A basic kitchenette with stock cabinets runs $7,000 to $12,000. A full kitchen with Cambria quartz counters, soft-close Wellborn cabinets, and a Kohler sink can hit $20,000 to $30,000. The same spread applies to the bathroom.
What Is an ADU, and What Does Miami Actually Allow?
An ADU, or accessory dwelling unit, is a secondary housing unit on the same lot as a primary residence. In Miami, you’ll hear them called efficiency units, in-law suites, casitas, or garage apartments. Florida law has steadily expanded where ADUs are allowed, and Miami-Dade’s zoning code permits them in many single-family residential districts, subject to lot size, setback, and parking requirements.
The typical Miami ADU runs 400 to 900 square feet and includes a small kitchen, a full bathroom, and a separate entrance. Some homeowners in neighborhoods like Westchester or Fontainebleau build them for aging parents. Others in Buena Vista or the Upper Eastside rent them long-term. And a growing number use them as home offices or studios that don’t require a separate commercial lease.
Before you plan anything, we recommend a quick zoning check with Miami-Dade’s building department. Setbacks in Miami are often smaller than people expect, but they’re strict, and the city enforces them. We handle that check as part of our written-price process, so you’ll know what’s buildable on your specific lot before you commit.
How Much Does an ADU Cost per Square Foot in Miami?
For a detached ADU in Miami, plan on $220 to $380 per square foot in 2026. An attached ADU runs $180 to $300 per square foot. A garage conversion can come in at $120 to $220 per square foot because you’re working inside an existing envelope.
That spread matters when you’re comparing quotes. A 500-square-foot detached unit at $250 per square foot is $125,000. The same square footage as a garage conversion at $160 per square foot is $80,000. Neither number is wrong; they’re different projects.
The per-square-foot rate also drops slightly as the unit gets larger, because fixed costs like permits, utility taps, and design fees get spread across more square feet. A 400-square-foot unit might run $300 per square foot, while a 900-square-foot unit might run $230 per square foot.
ADU Construction vs. Garage Conversion: Miami Cost Comparison
These are the two most common ways Miami homeowners add a secondary unit. They solve different problems at different price points.
- Full ADU construction: $106,200 – $259,600. You get a freestanding structure, full design control, and a truly separate living space. It takes four to seven months from permits to completion.
- Garage conversion: $35,400 – $94,400. You sacrifice covered parking but reuse the slab, walls, and roof. It’s typically faster, often three to five months, and aligns with Miami’s push for more housing without expanding building footprints.
One thing to check before choosing a garage conversion: Miami-Dade’s off-street parking requirements. Some single-family zones require at least one covered parking space. If converting your garage eliminates that, you may need to add a carport or driveway pad, which adds $4,000 to $8,000.
Hidden Costs in Miami ADU Construction
We’ve built enough ADUs in Miami to know where the surprise line items hide. Here’s what to watch for, and what we include upfront in our written price:
- Survey and soil test. Every ADU needs a current boundary survey ($600 to $1,500) and, in many parts of Miami, a soil boring test ($800 to $2,000) before foundation design can be finalized.
- Utility tap fees. Miami-Dade Water and Sewer charges connection fees that are separate from your contractor’s plumbing work. Budget $3,000 to $9,000 for a new connection, more if the main line is across the street.
- Impact fees. Miami-Dade collects impact fees on new residential square footage. Expect $2,000 to $6,000 for a typical ADU.
- Electrical service upgrade. Many older Miami homes, especially those built before 1980 in neighborhoods like the Roads or Biscayne Park, still have 100-amp panels. An ADU with its own mini-split, water heater, and kitchen appliances usually requires a 200-amp upgrade at $2,500 to $5,500.
- Landscaping and drainage repair. Construction tears up the yard. Restoring turf, adding a swale or catch basin for drainage, and replacing fence sections can add $2,000 to $7,000.
We put every one of these items in writing before we start. You will not get a verbal estimate that grows on the final invoice. That’s a core part of how Mason Remodeling works: written price before any work starts, every project, no exceptions.
How to Save on ADU Construction in Miami
Saving money on an ADU doesn’t mean cutting corners on the things that protect your home in a hurricane. It means making smart scope decisions early.
- Choose a garage conversion if the layout works. Reusing the slab, walls, and roof is the single biggest cost reduction available. You can put the savings toward better interior finishes.
- Keep the footprint simple. A rectangular floor plan with a simple gable roof costs far less to frame and roof than an L-shaped plan or one with dormers, hips, and valleys. Every corner adds labor and material.
- Use a mini-split instead of extending central HVAC. Running ductwork from the main house to an ADU is expensive and inefficient. A high-efficiency mini-split unit cools and heats a 600-square-foot space for $4,000 to $8,000 installed.
- Match the ADU’s scale to the existing utility service. If your panel can support a modest 500-square-foot unit without an upgrade, you just saved $3,000 to $5,000. Work with the power you have, not the power you’d need for a full-size second home.
- Pick mid-range finishes from manufacturer catalogs. KraftMaid cabinets, Silestone counters, and Moen fixtures are specification-grade products that hold up for decades without custom pricing. We have direct partnerships with these manufacturers, which means you get professional-grade material at catalog pricing, not showroom markup.
We offer free estimates on every ADU project in Miami. Call (850) 780-8123 and we’ll walk your lot, run the numbers, and give you a written price you can take to the bank, whether or not you hire us.
How Long Does ADU Construction Take in Miami?
A detached ADU in Miami typically takes 4 to 7 months from permit submission to final inspection. A garage conversion usually runs 3 to 5 months. Here’s how that time actually breaks down:
- Design and permitting: 6 to 12 weeks. Miami-Dade’s permitting process is thorough, and hurricane code review adds time compared to other Florida counties.
- Site work and foundation: 2 to 4 weeks, depending on excavation and whether elevation is required.
- Framing, roofing, and exterior: 4 to 6 weeks.
- Rough-in (plumbing, electrical, HVAC): 3 to 5 weeks.
- Finishes (drywall, flooring, cabinets, fixtures): 5 to 8 weeks.
- Inspections and final approval: 1 to 3 weeks.
Weather is a real factor in Miami. Summer afternoon thunderstorms slow exterior work, and we rarely schedule roofing or concrete during the heaviest rain weeks of June through September. A good construction schedule builds that in. Ours does.
FAQs – ADU Construction Cost in Miami
How much does an ADU cost in Miami in 2026?
A detached ADU in Miami costs $106,200 to $259,600 in 2026. Garage conversions run $35,400 to $94,400. Call (850) 780-8123 for a written, line-item price on your specific property.
Is it cheaper to build an ADU or convert a garage?
A garage conversion is almost always cheaper, typically $35,400 to $94,400 versus $106,200 to $259,600 for new construction. You save on foundation, framing, and roofing because the shell already exists. The tradeoff is losing covered parking and accepting the garage’s existing footprint.
Can I rent out my Miami ADU?
In many Miami-Dade single-family zones, yes, ADUs can be rented long-term. Short-term rentals under 30 days face additional restrictions and registration requirements in the city of Miami. We recommend confirming current rental rules with Miami-Dade’s zoning office before you invest, since the rules vary by municipality, from the city of Miami to Kendall to Palmetto Bay.
Does an ADU add resale value in Miami?
A well-built ADU typically adds $120,000 to $250,000 in appraised value in Miami’s current market, which often covers or exceeds construction cost. The exact figure depends on your neighborhood, square footage, and whether the unit is permitted. Unpermitted additions add far less at resale, which is one more reason to pull permits from day one.
How much does a garage conversion cost in Miami-Dade County?
A garage conversion in Miami-Dade County runs $35,400 to $94,400 depending on size, finish level, and whether you add a kitchen and bathroom from scratch or build on existing rough plumbing. Most one-car garage conversions with a full bath and kitchenette land between $55,000 and $75,000. Call (850) 780-8123 for a free estimate on your specific garage.
Why Homeowners Choose Mason Remodeling for ADU Construction
We’ve been building in Miami since 2004 as part of the Threshold Group family of home-service companies. Isaac Pruett leads our ADU construction team, and he’s the person who walks your property, reviews your plans, and signs off on every written price before it reaches your hands.
What that means for you, practically, is this: every person who steps onto your property is background-checked and identity-verified under The Threshold Standard. You get each crew member’s name and photo before they arrive, and they’ll show you a photo ID badge at the door, wearing a clean marked uniform. No strangers in your yard. No wondering who’s in your home while you’re at work.
Every Mason Remodeling project carries the 365-Day Done Right Promise: if the work is not right within a year of completion, we make it right at no cost to you. The guarantee is written, the terms are stated plainly, and a free return visit is part of it, no argument and no dispute process. Our home page spells out exactly what’s covered and for how long.
And every ADU project starts with a written price before any work begins. Not a verbal estimate. Not a ballpark. A written, line-item price delivered before a single tool is unpacked. If you’re considering an ADU construction project in Miami, we’ll show you the full scope, the full cost, and the full schedule before you sign anything.
Pricing reflects the Miami market as of 2026. Mason Remodeling Co Miami offers free estimates – call (850) 780-8123.
Written by Isaac Pruett, ADU Construction Lead at Mason Remodeling Co Miami, building accessory dwelling units across Miami-Dade County since 2004.
What Our Customers Say
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