What It Actually Costs to Convert a Garage to an ADU in Fort Myers
For a standard 400-550 sq ft single-car garage in Fort Myers, an all-in conversion to a legal accessory dwelling unit runs $60,000 to $115,000. See our Garage Conversion ADU Cost in Fort Myers, FL page for more detail on what drives that range. That number is not pulled from a national average. It reflects what we see on real job sites here: the cost of bringing a 1970s concrete block garage up to current Florida Building Code, meeting FEMA elevation requirements, and running new electrical service for a habitable living space with a kitchen and bath. Call us at (844) 638-7249 for an exact quote on yours. Estimates are free, and we do the three site checks that determine the real number before we give you one.
The Three Checks That Set the Real Budget
Derek Hollenbeck has been building in Lee County long enough to know that online garage conversion calculators are worse than useless here. They do not account for the three site conditions that swing a Fort Myers ADU budget by tens of thousands of dollars. Before we quote any job, we do these checks in the first 20 minutes on site.
1. Slab Elevation vs. Base Flood Elevation
We pull the parcel’s current elevation certificate and measure the existing garage slab against the FEMA Base Flood Elevation plus the City of Fort Myers freeboard requirement. If the slab is below the required finished floor elevation for habitable space, you have two paths. One is a raised floor system built inside the existing garage shell, which typically adds $8,000 to $20,000 depending on how much height you need and whether the existing walls can carry the load. The other is a tear-down and rebuild, which pushes the project into Home Additions & ADU in Fort Myers territory at $90,000 and up. Post-Ian FEMA advisory maps raised BFEs on some Fort Myers parcels by two to four feet, so garages that would have cleared elevation in 2021 suddenly do not. We catch this on day one, not after permitting kicks the plans back.
2. Electrical Service Capacity
Most garages built in Fort Myers between the 1950s and 1990s have a 60 to 100 amp subpanel, if they have one at all. That is not enough for a habitable ADU with a mini-split HVAC, electric range, water heater, and laundry. A panel upgrade plus an FPL service upgrade runs $4,000 to $9,000, and it requires coordinating with Lee County inspections and FPL on separate timelines. We handle that coordination in-house. You do not spend a Tuesday morning on hold with the utility company.
3. Wall Construction and Insulation
Fort Myers has a lot of concrete block garages. That is good for hurricanes, but it creates an insulation problem that out-of-state guides consistently get wrong. You cannot stuff batt insulation into a block wall cavity in Florida’s humidity and call it done. It traps moisture, grows mold, and rots your framing from the inside out. The correct approach here is closed-cell spray foam applied directly to the interior face of the block or rigid foam board with a thermal break. That detail alone can add $3,000 to $7,000 depending on square footage, and skipping it means you will have a dew point problem inside the wall assembly within the first rainy season. We use the right approach on every job because we live here too.
What the Project Scope Actually Includes
We do not sell partial conversions. When Groundwork Construction Co. of Fort Myers converts a garage to an ADU, it is a permitted, code-compliant, fully independent living unit. Here is what that scope looks like for a typical 450 sq ft single-car garage in Fort Myers.
Typical Garage-to-ADU Scope and Pricing
| Scope Item | Fort Myers Cost Range |
|---|---|
| Elevation correction (raised floor system) | $8,000 - $20,000 |
| Electrical panel and FPL service upgrade | $4,000 - $9,000 |
| Closed-cell spray foam insulation | $3,000 - $7,000 |
| Plumbing rough-in (kitchen, bath, laundry) | $7,000 - $14,000 |
| Mini-split HVAC system | $4,000 - $9,000 |
| Impact windows and exterior door | $5,000 - $11,000 |
| Drywall, flooring, trim, paint | $10,000 - $18,000 |
| Kitchenette (cabinets, countertops, sink, appliances) | $8,000 - $16,000 |
| Bathroom (shower, vanity, toilet, tile) | $7,000 - $14,000 |
| Permits, plans, engineering, Lee County fees | $4,000 - $7,000 |
| Total, 400-550 sq ft garage | $60,000 - $115,000 |
These are not bid ranges from a cost estimator tool. They are what our completed jobs in Fort Myers have actually landed at, pulled from project close-out sheets. The two biggest swing factors are the slab elevation situation and whether the existing electrical service can carry the load. A garage on a high-and-dry lot with a recent 200-amp panel already in place lands at the lower end. A 1962 block garage in a flood zone with a 60-amp fuse box lands at the upper end, and sometimes beyond it if structural surprises come up during demolition.
Why Permitting Here Is a Different Animal
Fort Myers sits in a Wind-Borne Debris Region requiring 160+ mph design wind speeds under the Florida Building Code. Much of the city falls within FEMA AE and VE flood zones. After Hurricane Ian, Lee County’s permitting pipeline became one of the busiest in the country, and the county tightened its plan review standards in response to a documented wave of unlicensed contractors doing non-compliant work. We pull permits, respond to plan review comments, coordinate FPL service upgrades, and manage elevation certificate reviews under one contract. You do not get handed off to a third-party expediter who disappears for two weeks. The home renovation market here demands that kind of accountability now, and we have been operating that way since well before the storm.
Every Groundwork project over $10,000 qualifies for $1,000 off and 0% financing for 18 months. That brings a $95,000 garage conversion down to a financed payment that does not gut your savings account. We provide upfront pricing with no surprises because we did the homework during the site visit, not after we opened the walls.
Common Fort Myers Garage Conversion Scenarios
These three situations come up constantly in our initial consultations. See which one sounds like your house.
- The 1970s block garage on a slab at grade. These are all over the McGregor corridor and older Fort Myers neighborhoods. The slab is almost always below current BFE. The walls are solid block but uninsulated. The electrical is a single 15-amp circuit for a garage door opener and one light. This scenario lands at $85,000 to $115,000 because it needs the full package: raised floor, new panel, spray foam, and complete MEP rough-in.
- The 1990s attached garage with a 100-amp subpanel. Common in newer subdivisions built to post-Andrew code. Slab elevation is sometimes compliant depending on the lot. The framing is wood, which simplifies insulation. These conversions run $65,000 to $85,000 because the bones are closer but the electrical still needs upgrading and impact glazing is mandatory.
- The garage that was never permitted in the first place. Fort Myers has a fair number of enclosed garages that were finished as bonus rooms without permits decades ago. If you are sitting on one of those, we need to assess what is behind the drywall before we can quote anything. The worst case is stripping it back to studs and starting over because the electrical and insulation were never done to code. Call us before you assume the structure is usable.
On every one of these, our technicians show up background-checked and in uniform. The crew that starts the job is the crew that finishes it. We do not sub out accountability.
Materials That Hold Up in Southwest Florida
A garage conversion in Fort Myers is a humidity test, a hurricane test, and a termite test all at once. We spec materials accordingly. For bathroom fixtures, we lean on Delta and American Standard for brass components that do not corrode in our water chemistry. For shower waterproofing, we use Schluter systems because a failed shower pan in an ADU you are renting out is a liability you do not want. These choices are not about brand names for the sake of it. They are about not getting a call two years later about tile popping off the wall because the substrate wicked moisture from the air.
The full conversion is backed by our 730-Day Done Right Promise. If something is not right, we make it right. That is one of the longest workmanship guarantees in residential construction, and we put it in writing because the building has to outlast the warranty.
FAQs
An all-in, permitted garage-to-ADU conversion in Fort Myers runs $60,000 to $115,000 for a typical 400-550 sq ft single-car garage. The final number depends on three site-specific factors we check on the first visit: slab elevation relative to FEMA Base Flood Elevation, existing electrical service capacity, and wall construction type. Every project over $10,000 qualifies for $1,000 off and 0% financing for 18 months. Call (844) 638-7249 for a free estimate that accounts for your actual site conditions.
Yes. A garage conversion into habitable space in Fort Myers requires building permits through the Lee County Building Department, and the plans must meet current Florida Building Code for wind loads, flood elevation, electrical, plumbing, and mechanical systems. If you are wondering Do I Need a Permit for a Home Addition? (Fort Myers, FL), the answer is yes, and we handle the full permit package, plan review response, and inspections under our contract. We handle the full permit package, plan review response, and inspections under our contract. Attempting the work without permits creates title and insurance problems that are far more expensive to fix than the permit fees.
It depends on what we find during the structural assessment. If the block walls and slab are intact and the flooding was freshwater, the conversion is typically viable with proper remediation, raised floor framing, and moisture management details. If the walls show saltwater intrusion cracking or the slab has settled, we may recommend a full rebuild. We will not convert a compromised structure because the long-term liability is not worth it for you or for us. Call (844) 638-7249 and we will assess it honestly.
A garage conversion is almost always less expensive than new detached construction in Fort Myers, provided the existing slab meets or can be made to meet elevation requirements. New detached ADUs start around $90,000 and go up from there because you are pouring a new foundation, framing new walls, and running all new utilities. See our Detached ADU Cost in Fort Myers, FL page for a detailed breakdown. A conversion that can use the existing shell and slab reliably saves $30,000 to $50,000. But if the slab is too low and the walls are in poor shape, the cost gap narrows fast. We walk you through the math on both options so you make the call with real numbers.
Start With a Site Visit, Not a Guess
We do not quote garage conversions over the phone. The numbers that matter are the ones we measure on your property. Call us at (844) 638-7249 to schedule a free estimate. Derek or one of our senior project leads will walk the garage with you, check the slab, the panel, and the walls, and give you a written number backed by 42 years of local construction experience and a 730-Day Done Right Promise. We do not just break ground. We build something worth standing on. Home Additions & ADU projects in Fort Myers start with an honest conversation. Let us have it on your driveway.
Written by Derek Hollenbeck, Owner & General Contractor, Groundwork Construction Co. of Fort Myers, serving Fort Myers, FL.
What Our Customers Say
"He told me one part of what I wanted was a bad idea structurally and offered an alternative instead of just taking the money."
- Angela Wong"Change orders were written down and priced before the work happened, every single time. No surprise at the end."
- Keisha Robinson"The schedule he gave me at the start was accurate to within four days on a three month job. Anyone who has done a renovation knows how unusual that is."
- Laura Bennett