What a garage conversion into an ADU in Burnt Store Marina costs and how long it takes
Converting a garage into a legal ADU in Burnt Store Marina typically runs between $45,000 and $130,000, with most single-car conversions landing near $55,000-$85,000 and larger two-car builds climbing past $100,000. The job usually spans 12 to 20 weeks from permit submission to final sign-off, though Charlotte County’s post-Ian review backlog has pushed some approvals to the longer end of that range. Call (844) 638-7249 for a free written estimate calibrated to your garage’s footprint, current condition, and elevation requirements.
How we convert a garage into a permitted ADU, step by step
A garage conversion ADU is not a weekend paint-and-carpet project. It is a full structural, mechanical, and finish-level transformation, and in Burnt Store Marina the process starts with the paperwork, not the sledgehammer. Here is how the job actually unfolds with our crew.
Stage 1 - Site survey, as-built measurements, and permitting package (2-4 weeks)
We laser-measure the garage slab elevation against the parcel’s current Charlotte County flood zone designation because post-Ian finished-floor heights often differ from what the original builder poured in the 80s or 90s. That number drives everything else: whether we need a stem-wall curb on the slab perimeter, what underlayment and moisture barrier are required, and how we detail the transition to the main house. While our drafter pulls permit drawings, we walk you through the five or six decisions that lock in the budget: bathroom placement, kitchenette scope, window and door sizes, HVAC type, and electrical panel capacity.
Stage 2 - Slab waterproofing, rough plumbing, and electrical rough-in (2-3 weeks)
Because Burnt Store Marina sits on Charlotte Harbor, groundwater and storm-driven moisture migrate laterally through slab-on-grade concrete. We apply a two-part penetrating silane sealer (we spec Quikrete or Sakrete depending on substrate condition) and lay a high-compression vapor barrier before any framing touches the floor. Rough-in plumbing for the bathroom and kitchenette goes in next, using marine-grade stainless supply-line clamps and brass compression fittings throughout. The electrical rough-in covers subpanel installation if the existing garage circuit cannot carry a 60-amp ADU load, which is common in 1980s-era CBS homes here.
Stage 3 - Framing, subfloor build-up, and window/door opening modifications (2-4 weeks)
The garage-door opening gets infilled with concrete block laid to match the existing CBS walls, and we cut new window and entry-door rough openings. If the finished floor needs to be raised to meet post-Ian FEMA freeboard requirements, we frame a pressure-treated subfloor grid and deck it with marine-grade plywood before any finish flooring goes down. This is the stage where the space stops looking like a garage and starts reading like a studio apartment, and it is also when we call the first Charlotte County framing inspection.
Stage 4 - Drywall, trim, kitchenette cabinetry, and bathroom finishes (3-5 weeks)
Insulated drywall goes up wall and ceiling, taped, textured, and primed. Our trim carpenters hang interior doors, set baseboards, and install the cabinet boxes for the kitchenette. The bathroom gets tile, a vanity, and a shower pan or walk-in unit. We schedule a mid-project walkthrough with you at this point so you can confirm fixture heights, paint color, and any last-minute trim-level choices before hardware goes on. A second rough trade inspection (plumbing, mechanical, and electrical) typically hits in the middle of this stage.
Stage 5 - Flooring, paint, final fixtures, and sign-off (2-3 weeks)
LVP or tile flooring goes in, walls get final paint, and we mount light fixtures, switches, cover plates, and the kitchenette backsplash. The HVAC system gets commissioned, the water heater fired, and we run every outlet with a circuit tester and verify hot-water delivery time to the bathroom. Charlotte County sends the final building inspector; we walk the unit together and you sign off. That final signature triggers the certificate of occupancy, and your Burnt Store Marina garage conversion ADU is legally rentable or guest-ready.
If this conversion is part of a larger whole-home reimagination, see how it fits under our Home Additions & ADU in Burnt Store Marina scope.
The spec decisions you will make for a garage conversion ADU
Half the cost of this job lives in the finish choices. Here are the categories where your selection pulls the budget up or down, and what we have learned from building ADUs in this specific marina community.
- Kitchenette: wet bar versus full galley. A wet bar with a sink, under-counter fridge, and microwave lands on the low end. A full galley with a four-burner cooktop, vent hood, dishwasher, and a 30-inch oven pushes the electrical and plumbing scope considerably higher. In Burnt Store Marina, we almost always recommend a hybrid: a two-burner induction cooktop and a compact dishwasher to keep the panel load manageable without sacrificing function.
- Bathroom: shower pan versus tiled walk-in. A prefabricated acrylic shower pan installs in a day and costs less. A site-built, mud-bed, tile-floor walk-in with a glass enclosure takes a week of skilled tile work and can add $4,000-$7,000. Salt air here is tough on exposed metal shower-door hardware; we spec solid-brass hinges and handles, not chrome-plated zinc.
- Flooring: LVP versus porcelain tile. Luxury vinyl plank runs $3-$6 per square foot installed and handles the slab moisture conditions well if the vapor barrier is done right. Porcelain tile with an anti-slip rating costs more in material and labor but shrugs off the humidity-and-sand combination that Burnt Store Marina residents track in from the docks.
- HVAC: mini-split versus tying into the main system. A dedicated high-SEER mini-split heat pump with a ceiling cassette costs more upfront but keeps the ADU on its own thermostat without taxing the main home’s air handler. Tying into the existing ducted system is sometimes possible but often undersizes the duct run, and Charlotte County mechanical inspectors flag it routinely on the load calculation.
- Windows and exterior door: impact-rated versus standard. This is the one choice with very little leeway in Burnt Store Marina. The wind-borne debris region maps put us squarely in a zone where any new opening in a dwelling unit must carry a Miami-Dade NOA or Florida Product Approval. We install insulated impact units, period. The cost difference versus non-impact is real, but it is not optional.
What a garage conversion ADU costs in Burnt Store Marina, FL
Garage conversion ADU pricing in Burnt Store Marina lands between $45,000 on the leanest single-car build and roughly $130,000 for a fully appointed two-car conversion with a separate entrance and dedicated HVAC. The wide spread exists because no two garages here start from the same condition. A 1990s CBS garage on an elevated stem-wall foundation with a serviceable panel and good slab drainage is a $55,000 project. The same square footage in a lower-sitting 1982 build that needs floor elevation, a subpanel upgrade, and full re-plumbing to the main stack can push past $90,000 quickly.
Five variables swing the number. First, square footage drives material quantity and labor, with every additional 100 square feet adding $8,000-$12,000 in finished space. Second, bathroom location relative to the existing sewer lateral determines whether we need a grinder pump and a long pressurized waste line, an easy $4,000 add. Third, the existing garage slab elevation versus the current flood map BFE determines if a subfloor build-up is required; raising a floor 12 to 18 inches adds structural framing, stair risers, and possibly ramping, which can cost $6,000-$10,000 on its own. Fourth, electrical service capacity, if the main panel lacks two open breaker slots for a 60-amp subfeed, the panel replacement or service upgrade adds $2,500-$5,000. Fifth, finish grade, where builder-grade cabinets and basic fixtures sit at the low end and custom cabinetry with quartz countertops and a tiled shower sit at the high end.
Every estimate we write is a fixed-price, line-item proposal. It includes the full scope: permitting, demolition, structural slab work, rough and finish plumbing and electrical, drywall, paint, flooring, kitchenette, bathroom, HVAC, and the final county inspection. What it does not include is the unforeseen condition behind a wall we have not opened yet, but we walk you through every contingency line during the estimate review, so you know what could surface and what it costs before you sign.
Many homeowners pair this project with interior finish work. We handle Cabinets & Countertops in Burnt Store Marina and Backsplash, Tile & Flooring in Burnt Store Marina as a natural extension of the ADU build.
What Burnt Store Marina homes specifically do to this job
Garage conversions in Burnt Store Marina are shaped by three forces that do not exist 15 miles inland. First, the post-Ian regulatory landscape is unforgiving. Charlotte County now enforces the revised FEMA flood maps with mandatory freeboard above Base Flood Elevation, and because so many of the community’s 80s-era CBS garages sit at or just above the original grade, we often have to raise the finished floor 12 to 18 inches on a pressure-treated sleeper system. That floor-height change cascades into step-down entry details, door threshold flashing, and sometimes a small deck or ramp at the entry. It is not complicated structurally, but it adds real dollars.
Second, salt air is relentless here. We see garage-slab spalling and embedded anchor- bolt corrosion in homes less than 20 years old because the morning onshore breeze carries a fine salt mist straight across Charlotte Harbor. Our standard spec for any steel embedded in the new ADU floor or walls is hot-dipped galvanized, G185 coating minimum. Standard electroplated hardware will show rust bloom within two wet seasons. We learned that the hard way on early post-Ian rebuilds.
Third, the split-jurisdiction reality along Burnt Store Road catches out-of-area contractors routinely. A property just east of the marina center may sit in Charlotte County for the house permit but Lee County for the seawall or dock component. We pull all the records before we open a permit file to confirm which jurisdiction owns which portion of the job, so inspections do not stall mid-project. Our Burnt Store Marina work never starts without crossing that jurisdictional bridge first.
Serving Burnt Store Marina, FL - Our Local Coverage Area
We’re based in the Burnt Store Marina 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 Burnt Store Marina
Yes. Charlotte County requires a full building permit for any garage-to-living-space conversion, including structural, plumbing, mechanical, and electrical sub-permits. The review runs through Charlotte County Building Construction Services, and the plans must demonstrate compliance with the current Florida Building Code and the post-Ian flood elevation requirements for your specific parcel. We handle the entire permit package, from the site survey through the final certificate of occupancy. Call (844) 638-7249 and we can pull your parcel’s flood zone and overlay district before you commit to anything.
Twelve to twenty weeks from permit submission to final sign-off. The construction portion is typically 8 to 12 weeks. The permitting front end runs 2 to 4 weeks with Charlotte County right now, and the inspection cadence depends on inspector availability, which has been tighter since the post-Ian rebuild surge. We build a three-week buffer into every schedule for weather days and inspection re-checks, so you are not staring at a calendar that was never realistic.
Yes, if the bathroom and kitchenette are placed along a wall that backs up to the existing main-house wet wall. Running a toilet drain horizontally across a slab to reach a distant stack requires either breaking and trenching the slab, which adds cost, or installing an above-floor macerating toilet and pump system, which is permitted but mechanically noisier. The smart money is on designing the floor plan around the existing drain-line location from day one.
Most conversions land between $160 and $240 per square foot, finished. A simple 240-square-foot studio with a kitchenette and a three-quarter bath will run near the upper end of that range per foot because the bathroom and kitchenette are fixed-cost items that do not scale linearly. A 500-square-foot one-bedroom layout spreads those fixed costs over more area and typically comes in closer to $170 per square foot. The exact number depends on the five variables we covered above. Our estimates are fixed-price and free, so you will see every line before you decide.
Every garage conversion ADU we build in Burnt Store Marina is covered by our 730-Day Done Right Promise. If something is not done right, we make it right, no fine print and no runaround. That covers workmanship, materials we install, and the systems we build. It is one of the longest warranties in residential construction, and the owner, Derek Hollenbeck, stands behind it personally. We also pass through every manufacturer warranty on fixtures, appliances, and finish materials, so you are protected on every layer of the build.
Get a free written estimate for your Burnt Store Marina garage conversion
If you are serious about turning your garage into a legal, rentable ADU in Burnt Store Marina, let us walk the space and give you a fixed-price, line-item estimate that spells out exactly what the job costs and how long it takes. We answer the phone live, 24/7, and we show up on time in a marked truck. Call (844) 638-7249 to schedule your free estimate, or reach out to our Home Additions & ADU team directly. No pressure and no vague numbers.
Written by Derek Hollenbeck, Owner at Groundwork Construction Co., serving Burnt Store Marina with upfront pricing and the 730-Day Done Right Promise.