What Does a Garage Conversion ADU Cost and Involve in Lantana?
A garage conversion ADU in Lantana typically runs $30,000-$80,000 and takes 8-14 weeks from permit to final inspection, depending on whether your existing slab needs elevation work and how much plumbing or electrical gets relocated. Most Lantana homeowners call us at (844) 665-0162 after realizing their 1950s or 1960s garage has the bones for a studio or one-bedroom unit but needs everything else brought to code. We handle the full build, including permits, so you’re not coordinating separate trades through Palm Beach County’s inspection cycle.
Lantana’s coastal position on the Intracoastal Waterway means we approach these conversions differently than inland contractors. Salt air attacks exposed hardware within months, and the town’s flood-code environment can trigger elevation requirements that don’t apply a few miles west. Here’s how we structure the work and what you’ll need to decide at each stage.
How We Convert a Lantana Garage into a Legal ADU
Every garage conversion ADU we build in Lantana follows five distinct stages. We’ve refined this sequence across dozens of Palm Beach County projects, and the timeline holds steady unless we hit unexpected structural issues in older CBS construction.
Stage 1: Flood-code and feasibility review (1-2 weeks)
Before we touch a wall, we pull your FEMA flood map and the Palm Beach County Property Appraiser’s assessed value for your structure. In Lantana’s AE zones, if your total project cost plus any improvements from the past five years exceeds 50% of that assessed value, the county classifies this as substantial improvement and triggers full flood-elevation compliance. That can mean raising the finished floor above Base Flood Elevation, a $15,000-$40,000 line item that reshapes the entire budget. You’ll know this number before we sign anything, not after permits are filed.
Stage 2: Design, permit drawings, and submission (3-5 weeks)
Our architect drafts plans showing the converted layout, new egress window placement, kitchenette or full kitchen configuration, bathroom location, and tie-ins to existing utilities. Palm Beach County requires impact-rated openings and verified roof-to-wall connections on substantial work, so we spec those from the start. You decide here: studio layout or one-bedroom, kitchenette or full kitchen, and whether the bathroom stacks with existing plumbing or needs new trenching. We submit to the county and manage revision requests.
Stage 3: Demolition and structural prep (1-2 weeks)
We strip the garage to block, evaluate the slab for elevation requirements, and install any needed stem walls or fill. If your 1960s flat roof needs re-tying to walls for hurricane uplift, we handle that now. This is also when we run new electrical from your panel, which in many Lantana homes means upgrading from 100-amp service to 200-amp. You’ll see the rough framing and confirm door and window placements before we close walls.
Stage 4: Systems and finishes (4-6 weeks)
Plumbing rough-in, electrical, HVAC mini-split installation, insulation, drywall, flooring, cabinets, countertops, fixtures, and paint. We use stainless or hot-dipped galvanized fasteners and hurricane strapping throughout, never standard hardware that’ll rust through in two seasons. You choose materials during pre-construction meetings so there’s no decision fatigue mid-project.
Stage 5: Inspections and final walkthrough (1-2 weeks)
Palm Beach County inspects structural, electrical, plumbing, and final occupancy. We schedule and attend every inspection. Once the certificate of occupancy issues, we do a punch-list walkthrough together and turn over warranty documentation.
The Options You’ll Choose Between for Your Garage Conversion ADU
These choices determine how the space functions, how long it lasts, and what you’ll spend beyond the base construction cost:
- Kitchen configuration: A wet-bar-style kitchenette with a mini-fridge and two-burner cooktop runs $3,500-$7,000. A full kitchen with full-size appliances, custom cabinetry, and stone countertops pushes $12,000-$22,000. For rental ADUs, the full kitchen commands higher rent; for in-law use, the kitchenette often suffices.
- Bathroom scope: A three-quarter bath (shower, toilet, sink) tucked against existing plumbing stacks costs $6,000-$10,000. A full bath with a tub or large walk-in shower, especially if we trench new drain lines through the slab, runs $10,000-$18,000. In Lantana’s older homes with cast-iron drains, we sometimes find the existing line has insufficient fall; replacing it adds $2,000-$4,500.
- Flooring: Luxury vinyl plank (LVP) at $4-$7 per square foot installed handles humidity well and cleans easily for tenants. Tile at $6-$12 per square foot lasts longer but feels colder. We don’t recommend carpet in coastal garage conversions; moisture wicks through older slabs.
- HVAC approach: A ductless mini-split ($2,500-$5,000 installed) is the standard for garage conversion ADUs in Lantana. Extending your home’s central system usually requires upsizing the main unit and running ductwork through the attic, which can cost more and perform poorly if the original system was barely adequate.
- Elevation and flood compliance: If triggered, raising the slab or building a stem-wall system with flood vents adds $15,000-$40,000 but protects your investment and satisfies the county. Skipping it isn’t an option once the 50% threshold is crossed.
Many homeowners pair the finished interior with Cabinets & Countertops in Lantana selected from our curated brand range, or extend the upgrade to Backsplash, Tile & Flooring in Lantana for a cohesive look that matches the main house.
What Garage Conversion ADU Costs in Lantana, FL
| Project Element | Typical Range |
|---|---|
| Base garage conversion ADU (studio, kitchenette, 3/4 bath) | $30,000 - $55,000 |
| Mid-range conversion (1-bedroom, full kitchen, full bath) | $50,000 - $70,000 |
| High-end conversion with slab elevation or flood compliance | $65,000 - $80,000 |
| Electrical service upgrade (100A to 200A) | $3,500 - $6,500 |
| HVAC mini-split system | $2,500 - $5,000 |
Five factors push your project to the low or high end of these ranges:
1. Existing garage condition. A dry, structurally sound block garage with a level slab starts cheap. A detached garage with a cracked slab, rotted wood framing, or active water intrusion needs remediation first.
2. Plumbing relocation distance. If your bathroom stacks directly above or beside existing drains, you save thousands. Trenching new lines across the footprint to reach the main sewer connection adds labor and material.
3. Flood-elevation trigger. The 50% substantial-improvement rule is the single biggest cost variable in Lantana. We calculate this before contract signing so you’re not surprised mid-project.
4. Material grade. Stock cabinets and LVP keep costs down. Custom cabinetry, Silestone or Caesarstone countertops, and premium fixtures move the number up but also improve durability and rental appeal.
5. Permit scope and HOA requirements. Some Lantana neighborhoods require architectural review beyond county permits. We identify this early and build that timeline into our schedule.
A written estimate from Groundwork includes demolition, framing, electrical, plumbing, HVAC, insulation, drywall, flooring, fixtures, cabinets, countertops, paint, permits, and inspections. It does not include furniture, window treatments, or separate appliance purchases unless specified.
What Lantana Homes Specifically Do to This Job
Lantana’s housing stock shapes every garage conversion ADU we build here. The town is almost entirely concrete block stucco homes from the 1950s through 1970s, many with flat or low-slope built-up roofs, original jalousie windows, and 100-amp electrical panels that predate modern hurricane and energy codes. These aren’t flaws; they’re parameters we design around.
The coastal climate is the hidden cost driver. Sitting less than a mile from the Atlantic on the Intracoastal, Lantana’s salt-laden air corrodes exposed metal fasteners, anchor bolts, flashing, and hurricane strapping years faster than inland Greenacres or Lake Worth Corridor. We specify stainless steel or hot-dipped galvanized hardware on every connection, and we inspect existing roof-to-wall ties for rust before adding load. A contractor who specs standard zinc-coated fasteners here is building in a failure timeline.
Palm Beach County’s post-Andrew wind code adds another layer. Impact-rated openings and verified roof-to-wall connections are required on all substantial work, not optional upgrades. We price these from the first estimate because retrofitting them after framing is complete costs more and delays inspection.
The flood-code dynamic is uniquely consequential in Lantana. A seasoned contractor knows to pull the FEMA flood map and county assessed value before any contract is signed. We’ve seen straightforward garage conversions on 1962 CBS homes near Hypoluxo Island or the waterfront streets along the Intracoastal quietly cross the 50% threshold, legally converting the permit into a new-construction flood event and forcing slab elevation. That five-figure surprise kills deals if it surfaces after commitment. We surface it on day one.
This work is part of our broader Home Additions & ADU in Lantana capability, and our Home Additions & ADU crew draws from the same process discipline we apply across all seven residential project categories. We serve Lantana and surrounding Palm Beach County communities from our Fort Lauderdale base.
Serving Lantana, FL - Our Local Coverage Area
We’re based in the Lantana 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 Lantana
Most projects take 8-14 weeks from permit submission to certificate of occupancy, with 3-5 weeks in the design and permitting phase before construction starts. Palm Beach County’s inspection schedule and any required flood-elevation work are the main variables. Call (844) 665-0162 and we’ll review your specific timeline based on your property’s flood zone and existing conditions.
Yes. Palm Beach County requires permits for structural, electrical, plumbing, and mechanical work, plus a final occupancy inspection. If your project exceeds the 50% substantial improvement threshold relative to your home’s assessed value, FEMA flood-elevation compliance also becomes mandatory. We handle all permit applications and inspections as part of our standard process.
Sometimes, but rarely completely. Most Lantana garages lack the plumbing rough-ins and adequate electrical service for a legal dwelling unit. If your bathroom location stacks with existing drains and your panel has spare capacity, you can minimize relocation costs. During our feasibility review, we map your existing systems and show you exactly what can stay and what must move.
The lowest-cost path is a studio layout with a kitchenette, three-quarter bath stacked to existing plumbing, LVP flooring, stock cabinetry, and no flood-elevation trigger, typically landing near $30,000-$40,000. Skipping the flood-code review to save money is a mistake we’ve seen backfire; a post-contract elevation requirement can double your cost. We price the full compliance path upfront so you can compare real numbers.
We warranty our workmanship for one year from final completion, and all materials carry their manufacturer warranties, which range from 10 years to lifetime depending on the product line. Our installation of Kohler fixtures, for example, is backed by Kohler’s own coverage, and our electrical and plumbing work meets or exceeds Florida state requirements. We document all warranties at handoff so you have clear recourse without hunting down paperwork later.
Get a Free On-Site Estimate for Your Garage Conversion ADU in Lantana
We’ll walk your garage, review your flood zone and assessed value, and deliver a written estimate with real numbers for your specific situation. No obligation, no surprise elevation requirements after you sign. Call (844) 665-0162 to schedule, or tell us about your project and we’ll confirm what stage one looks like for your property.
Written by Raymond Estevez, Owner at Groundwork Construction Co., serving Lantana and South Florida homeowners since our founding.