Garage Conversion ADU in Miami Beach: Scope, Timeline, and What You’ll Pay
A garage conversion ADU in Miami Beach turns your existing garage structure into a permitted, self-contained dwelling unit with its own kitchen, bath, sleeping area, and separate entrance. Most conversions we handle in Miami Beach run 4 to 7 months from signed contract to final inspection, with permit review alone taking 8 to 12 weeks through the city. Expect to invest between $30,000 and $80,000 depending on whether your garage is already built to current Miami-Dade code or needs structural, elevation, or utility upgrades to qualify as habitable space. Call (844) 665-0162 and we’ll walk your specific garage in person, no charge.
How We Convert a Garage into an ADU, Step by Step
Every garage conversion ADU in Miami Beach follows a sequence we’ve refined across dozens of local projects. Here’s what actually happens, who decides what, and how long each stage takes.
Stage 1: Feasibility and Existing Conditions Survey (Week 1-2)
We start with a forensic walk-through of your garage, not a quick measurement. In Miami Beach, we’re checking three things that mainland contractors often miss: the slab elevation relative to the newly raised street grade, evidence of chloride-driven rebar corrosion in the walls and foundation, and whether the existing roof structure can carry the mechanical loads of a conditioned living space. You’ll decide at this stage whether you want a full architectural survey or if a structural engineer’s targeted report suffices. Most homeowners need the latter; historic district properties in South Beach almost always need both. This stage costs nothing beyond the engineering fee if you move forward with us.
Stage 2: Design, Permitting, and Product Selections (Week 3-14)
This is where the calendar stretches. Miami Beach’s building department requires full plans stamped by a Florida-licensed architect or engineer, plus Miami-Dade NOA-certified product approvals for every window, door, and impact-rated opening. We submit simultaneously for city building permits and, if you’re in a historic district, Miami Beach Historic Preservation Board approval. While permits process, you’ll make your material selections: flooring type, kitchen cabinet line, countertop surface, bathroom fixtures, and whether you want a mini-split system or tied-in central HVAC. We bring samples from our 50+ brand partnerships to your home so you’re not driving to showrooms. Most clients lock selections by week 8 so we can pre-order long-lead items.
Stage 3: Demolition, Structural Prep, and Utility Rough-In (Week 15-22)
We strip the garage back to structure: remove the overhead door, infill that opening with framed wall and a code-compliant egress door or window, and expose the slab for inspection. In Miami Beach, this is where we often discover the real work. The original slab may sit below current flood elevation, requiring us to raise it or install flood vents. Water table here sits just a few feet below grade, so any below-slab plumbing or drainage work gets complicated fast. Electrical service often needs upgrading from 100-amp to 200-amp to handle the additional dwelling unit. We’ll show you what we find, document it with photos, and give you a change-order price before proceeding. No surprises.
Stage 4: Build-Out and Systems Installation (Week 23-32)
Framing, insulation, drywall, flooring, kitchen and bath install, trim carpentry, paint. This is the visible progress stage. For garage conversion ADU projects in Miami Beach, we typically specify moisture-resistant drywall, tile or luxury vinyl plank flooring (never solid hardwood against slab-on-grade), and either a compact kitchen from KraftMaid or Wellborn or a custom layout if the footprint demands it. Countertops run from Silestone or Caesarstone engineered quartz for durability against humidity, or a budget laminate if this is a rental unit. Kohler and Moen fixtures hold up better than builder-grade against our salt air. You’ll do a midpoint walkthrough after drywall to confirm outlet and switch placements, then a pre-final punch list.
Stage 5: Inspections, Certificate of Occupancy, and Handover (Week 33+)
Miami-Dade requires rough and final inspections for structural, electrical, plumbing, mechanical, and energy code compliance. The city also requires a final flood elevation certificate if we modified the slab or entry level. We schedule inspectors, meet them on-site, and handle any corrections. Once the Certificate of Occupancy issues, we do a formal walkthrough with you, document warranty information for all installed products, and transfer manufacturer registrations. You’re now free to rent the unit, house family, or list it short-term if your zoning allows.
The Options You’ll Choose Between for Your Garage Conversion ADU
Every decision below affects your final number and how the space lives. Here’s the honest trade-off on each.
- Garage door infill method: Framed wall with stucco to match the house is standard and least expensive. If your garage faces the street in a historic district, the Miami Beach Historic Preservation Board may require cast stone or original-profile stucco, which adds $3,000-$8,000 but preserves curb appeal and compliance.
- Slab condition and elevation: Leave the existing slab as-is if it’s structurally sound and above base flood elevation. If it’s delaminating or below grade relative to the raised street, we break it out, install a vapor barrier, and pour new with integral footings. That’s an $8,000-$18,000 swing but eliminates future moisture and flood insurance headaches.
- Kitchen scope: A kitchenette with mini-fridge, two-burner cooktop, and single-bowl sink runs $4,000-$7,000 installed. A full kitchen with full-size appliances, dishwasher, and 8-10 cabinets runs $12,000-$22,000. Rental ADUs typically get the kitchenette; family units or long-term rentals get the full kitchen.
- Bathroom configuration: A wet bath (shower over toilet, no separate enclosure) fits in 25 square feet and costs $5,000-$9,000. A separate tub or shower with vanity and water closet needs 40+ square feet and runs $10,000-$18,000. Space usually decides this for you, not budget.
- HVAC approach: Ductless mini-split is the default for garage conversion ADU work in Miami Beach: $3,500-$6,500, no ductwork, efficient cooling. Tying into existing central system only works if your current unit has capacity, which it usually doesn’t after decades of salt-air degradation. We check that first.
- Utility connection strategy: Sub-meter through the main house’s existing service is cheapest but creates landlord-tenant billing complexity. Separate meter from FPL requires trenching, a new service pedestal, and FPL coordination, typically $4,000-$9,000 more. Most rental ADU owners choose separate meter; family use cases often don’t.
What Garage Conversion ADU Costs in Miami Beach, FL
| Project Element | Typical Range |
|---|---|
| Base garage conversion ADU (good condition garage, standard finishes) | $30,000 - $50,000 |
| Mid-range conversion (slab work, upgraded kitchen/bath, mini-split) | $50,000 - $65,000 |
| Full renovation (structural repair, flood elevation, premium finishes) | $65,000 - $80,000 |
Five factors push you up or down this range. First, garage size: a single-car at 240 square feet versus a double at 480 square feet doubles your flooring, drywall, and paint but not your fixed costs like permits and kitchen. Second, existing condition: a 1960s MiMo garage with spalling concrete and corroded rebar needs forensic repair before we build, adding $10,000-$25,000. Third, utility relocation: moving your electrical service, adding a sewer ejector pump if the main line sits above your slab, or running new water lines from the street. Fourth, material grade: laminate counters and stock cabinets versus Silestone or Caesarstone with semi-custom cabinetry. Fifth, permit scope: a simple conversion with no exterior changes moves faster than one requiring Historic Preservation Board review and flood elevation certificates.
Our written estimate includes demolition, disposal, all rough and finish carpentry, electrical and plumbing to code, HVAC, insulation, drywall, flooring, paint, fixtures, and final cleanup. It does not include separate meter installation from FPL, window treatments, or furniture. We flag those line items explicitly so you’re not guessing.
What Miami Beach Homes Specifically Do to This Job
Miami Beach sits on a barrier island roughly four feet above sea level, flanked by salt water on both sides, and that geography turns every garage conversion ADU into a coastal construction problem. The omnidirectional salt air drives chloride intrusion into concrete years faster than you’d see in Fort Lauderdale or Hialeah. We regularly open garages in Mid-Beach’s 33140 ZIP and find active rebar corrosion where the slab meets the foundation wall, not because the original builder cut corners, but because forty years of Atlantic exposure does what it does. That means forensic investigation and patch-and-seal restoration before we ever frame a wall.
The city’s “Rising Above” program has elevated many streets in South Beach and parts of Mid-Beach by one to two feet, which creates a specific headache for garage conversions. Your garage slab, permit-compliant when built, may now sit below the adjacent road grade. That triggers FEMA flood requirements for new construction and substantial renovations: flood vents, elevated mechanicals, or in extreme cases, slab replacement. We’ve walked sites on Alton Road and Meridian Avenue where the original driveway slope now drains toward the garage instead of away. We catch that in our initial survey, price it honestly, and design around it.
Permitting in Miami Beach also means Miami-Dade NOA-certified products for every opening. Your new egress window or door must carry the Miami-Dade County Product Control Approval stamp. We source from Andersen, Pella, and Miami Beach-approved suppliers so there’s no last-minute substitution. And if your property falls within a historic district, the Miami Beach Historic Preservation Board reviews exterior alterations independently. We’ve navigated that process for Art Deco structures where the board mandated original stucco profiles and window geometries. It adds time, but it’s non-negotiable, and we build it into our schedule from day one.
Homeowners doing a garage conversion ADU here often pair the interior work with Cabinets & Countertops in Miami Beach for the main house kitchen, or Backsplash, Tile & Flooring in Miami Beach to unify the property’s finishes. Since Groundwork handles every phase, you don’t coordinate separate trades. Home Additions & ADU projects are our full-scope bread and butter, and this garage conversion sits naturally within that capability alongside Home Additions & ADU in Miami Beach as part of a larger property strategy.
Serving Miami Beach, FL - Our Local Coverage Area
We’re based in the Miami Beach area and know this community well. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
Frequently Asked - Garage Conversion ADU in Miami Beach
Most garage conversion ADU projects in Miami Beach take 4 to 7 months from contract to Certificate of Occupancy, with permit review consuming 8 to 12 weeks of that timeline. Historic district properties or those requiring flood elevation work add 4 to 8 weeks. Call (844) 665-0162 and we’ll give you a realistic schedule based on your specific address and garage condition.
Yes, absolutely. Miami Beach requires full building permits for any garage conversion ADU, plus Miami-Dade NOA-certified products for all openings and, in many cases, a separate flood elevation certificate. We handle the entire permit package, including architect or engineer stamps, so you don’t navigate that bureaucracy alone.
Sometimes, but rarely in Miami Beach’s older housing stock. Most garages lack the sewer connection, water supply, and electrical capacity for a dwelling unit. We evaluate this in our initial survey and give you a straight answer: if your service panel has spare amperage and the sewer main is accessible, you might save $5,000-$12,000. If not, we price the utility work upfront with no surprises.
Typically yes. A garage conversion ADU in Miami Beach runs $30,000-$80,000, while new detached ADU construction starts around $90,000 and climbs past $200,000. You’re leveraging existing walls, roof, and foundation. The savings disappear if your garage needs extensive structural repair, flood elevation, or historic compliance work, which is why our feasibility survey matters.
We warranty our workmanship for one year from Certificate of Occupancy. All materials carry their manufacturer warranties, which vary by product: Kohler fixtures carry limited lifetime, Silestone and Caesarstone carry 25-year residential, and cabinet warranties range from 5 years to limited lifetime depending on the line you select. We register every product in your name so you’re not chasing paperwork later.
Ready to See What Your Garage Can Become?
Call (844) 665-0162 for a free, on-site estimate for your garage conversion ADU in Miami Beach. Raymond Estevez or a senior project manager will walk your garage, check slab condition, elevation, and utility access, and deliver a written estimate within 48 hours. No pressure, no generic pricing, just the specific numbers for your property.
Written by Raymond Estevez, Owner at Groundwork Construction Co., serving Miami Beach since our founding in South Florida.