What a New Detached ADU in Fort Myers Really Costs and How Long It Takes
A new detached ADU in Fort Myers runs $90,000 to $220,000, and from signed contract to final inspection you’re looking at 5 to 9 months depending on site prep, foundation type, and Lee County’s permit queue. That range covers a fully permitted standalone unit with its own utilities, kitchen, bath, and foundation - not a prefab shed dropped in the backyard. Call (844) 638-7249 for an on-site walkthrough and a written line-item estimate specific to your property.
How We Build a Detached ADU in Fort Myers, From Clearing to Keys
A standalone backyard unit isn’t a weekend shed project. It’s a full residential structure subject to the Florida Building Code, and every step from lot survey to final CO touches at least two Lee County inspectors. Here’s what the process actually looks like when we run it.
Stage 1: Site Survey, Soils, and Permit Drawings (Weeks 1-4)
We start with a boundary and topo survey to confirm setbacks and easements. Fort Myers’ zoning code for ADUs sits inside Lee County Land Development Code Chapter 34, and minimum setbacks of 7 to 10 feet are standard for detached accessory structures - your specific lot determines where the unit can actually go. A geotech engineer drills soils to set the foundation design; sandy-loam caps over limestone are common across Fort Myers, and bearing capacity here usually lands between 2,000 and 3,000 psf, which keeps slab-on-grade pricing predictable. Once we have survey and soils, our draftsman produces sealed permit drawings. Lee County plan review for an ADU takes 3 to 6 weeks depending on volume - post-Ian rebuild permits still run through the system in large numbers, so we submit early and track daily.
Stage 2: Foundation and Utility Trenches (Weeks 5-7)
After permit issuance, we clear and grade the pad, dig footers, and set form boards. If your lot sits in a FEMA AE flood zone - and large sections of Fort Myers do - we raise the finished floor elevation to match or exceed the current Base Flood Elevation plus Lee County’s freeboard requirement. That means a stem-wall foundation or a compacted-fill raised slab instead of a simple slab-on-grade. Underground rough-in follows immediately: water line tap from the main house or a separate meter, sewer lateral tied into the existing line or a new septic connection if you’re on septic, and a dedicated subpanel feed trenched from the main service. At this stage the homeowner decides the kitchen and bath fixture layout. Moving a sink or shower drain after the slab is poured adds real money, so we lock the floor plan here.
Stage 3: Framing, Drying In, and Rough-In (Weeks 8-14)
We frame walls and roof trusses, sheathe, and install the roofing underlayment. Florida Building Code in Fort Myers requires wind-load framing connectors and strapping rated for 160+ mph design wind speeds - every truss gets hurricane clips, every wall top plate gets strapped to the foundation. Windows and exterior doors go in at this stage; impact-rated glazing is code minimum for new construction in a Wind-Borne Debris Region, so Andersen and PGT are the spec we write most often. We rough in electrical, plumbing, and HVAC, and the homeowner walks the space to confirm switch and outlet placement. A sheath inspection happens next: Lee County building inspector checks strapping, nailing patterns, and window/door anchors before we can insulate and drywall.
Stage 4: Insulation, Drywall, and Interior Finishes (Weeks 15-20)
Closed-cell spray foam or R-13 batts with a radiant barrier go in, drywall hangs and finishes to Level 4, and we install doors, baseboards, and casing. Kitchen cabinets, countertops, bathroom vanity, and tile or LVP flooring follow. This is the stage where your material selections become the finished space: KraftMaid cabinets in the kitchenette, Kohler fixtures in the bath, a Cambria quartz counter if you chose that upgrade. Paint goes on last, after trim. During this stretch we also pull any specialty trade permits - mechanical, plumbing fixture, and electrical final connections - and schedule those rough-in inspections so nothing backs up against your final.
Stage 5: Final Inspections, Punch List, and Certificate of Occupancy (Weeks 20-26)
A Lee County building inspector and a fire marshal walk the unit: they check egress, smoke and CO detectors, GFCI protection, stair and handrail code, and structural sign-offs from each trade. If you’re in a Fort Myers neighborhood with an HOA, their final walkthrough often mirrors the county’s, and we coordinate that date so both happen in the same window. We run a punch list with you - paint touch-ups, door adjustments, anything cosmetic - and clear it before the CO is issued. Once you have the Certificate of Occupancy, the unit is a legal dwelling. Total groundbreak to CO on a detached ADU in Fort Myers averages 5 to 7 months for a slab-on-grade build, 7 to 9 months if you’re on a raised foundation with elevated finishes.
The Options You’ll Choose Between When We Build Your Fort Myers ADU
An ADU isn’t one product with one price. Four or five decisions move the number by $20,000 or more. Here are the big ones, with the honest trade-offs we walk through on every estimate.
- Foundation type: slab-on-grade vs. raised stem wall. If your lot is in an AE flood zone and Base Flood Elevation mandates a raised floor, that adds $12,000-$22,000 over a simple slab. For lots outside the floodplain, slab-on-grade keeps the cost down and moves faster.
- Kitchen configuration: kitchenette vs. full galley kitchen. A kitchenette with a two-burner cooktop, undercounter fridge, and a single-basin sink runs $7,000-$11,000 installed. A full galley with a four-burner range, dishwasher, and 24-inch refrigerator pushes $14,000-$20,000. The plumbing rough-in difference is modest; the appliance and cabinet run is what climbs.
- Exterior finish: HardiePlank lap siding vs. stucco over CMU block. Hardie is the faster, slightly lower-cost option on a wood-frame ADU and holds paint well in Fort Myers humidity. Stucco over block costs more upfront but delivers better impact resistance and a longer maintenance cycle. Abodu and similar panelized systems can shorten framing time but require a crane set and pre-poured slab - they’re not always cheaper, but they’re faster.
- HVAC: mini-split vs. central ducted system. A high-SEER multi-zone mini-split handles cooling and humidity control beautifully for a 400-900 sq ft floor plan and typically runs $4,500-$7,500 installed. A central split system with ducts in the attic adds $3,000-$5,000 and eats ceiling height. For most detached ADUs in Fort Myers, mini-splits are the smarter pick - quieter, more efficient, and less invasive to install.
- Windows and doors: impact-rated vs. standard with shutters. Code requires impact-rated glazing on new construction here. Andersen 100 Series impact windows are our default spec; upgrading to Andersen 400 Series or Marvin elevates the price but delivers a tighter air seal and better sound attenuation if your ADU backs up to a busy street like McGregor Boulevard or Daniels Parkway.
What a New Detached ADU Costs in Fort Myers, FL
A new detached ADU in Fort Myers lands between $90,000 and $220,000. The low end reflects a 400 sq ft studio with a kitchenette, slab-on-grade foundation, standard impact windows, and a mini-split - on a clear lot outside a flood zone. The high end is a 900+ sq ft one-bedroom unit with a full kitchen, raised stem-wall foundation in an AE flood zone, upgraded Andersen 400 windows, and a central HVAC system. Everything we quote is a fixed price in writing. No change orders show up later unless you change the scope.
Four variables drive the spread:
- Square footage. Every additional 100 sq ft adds roughly $18,000-$25,000 when you’re building to finished-livable standard.
- Foundation complexity. A raised slab for flood compliance is the biggest single cost swing on the whole project.
- Utility distance. Trenching an electrical feeder and water line 120 feet from the main house costs more than running it 30 feet. So does a new septic field for a property not connected to city sewer.
- County impact fees and school fees. Lee County assesses impact fees on new dwelling units; for an ADU under 750 sq ft the fee load is lighter than for a full second home, but it’s still a line item that raw material pricing alone doesn’t capture.
Our written estimate breaks out every line - site work, foundation, framing, MEP rough-in, finishes, and permit fees - so you know exactly where the money goes. Call (844) 638-7249 to schedule a free on-site estimate and walkthrough.
What Fort Myers Homes Specifically Do to This Job
Fort Myers was ground zero for Hurricane Ian’s Category 4 landfall in 2022, and that event rewrote the rulebook for new residential construction here. Lee County’s permit pipeline processed tens of thousands of post-storm rebuild permits, and the FEMA flood map remapping that followed raised Base Flood Elevations on many parcels by 2 to 4 feet. What that means for your ADU: a lot that was outside the flood zone in 2021 may require a raised foundation today, and we verify that against the current FEMA panel before we draw the first site-plan line. If you own one of the older concrete-block homes along the McGregor corridor, your main house was likely built well before the 2002 Florida Building Code wind standards, and a new ADU on the same parcel will be held to a completely different structural standard - hurricane straps, impact glazing, tie-down anchors - that the original house may not have. The disconnect between pre- and post-code construction on the same lot is something we navigate on nearly every detached ADU build in Fort Myers.
We also design around what the post-Ian contractor landscape taught this market. After the storm, Lee County saw waves of unlicensed crews taking deposits and disappearing, and the DBPR ran joint enforcement sweeps to clear them out. Homeowners here got burned in ways that towns further inland didn’t. That’s why we carry Lee County license verification on every estimate, and why every crew member who shows up on your property is background-checked and uniformed. You’ll know exactly who you’re letting onto your property. We also coordinate HOA design-review submissions for neighborhoods like Gulf Harbour, Timber Creek, and Reflection Lakes, where detached accessory structures need architectural committee approval before Lee County will even accept the permit application. Navigating that dual-approval timeline is part of the local job.
When homeowners pair a new ADU with interior work on the main house, we often see them roll in kitchen updates at the same time - Kitchen Design & Layout in Fort Myers so the main house and the ADU share a consistent finish level. Some also upgrade flooring or tile across both structures - that ties directly into our Backsplash, Tile & Flooring in Fort Myers work. And for the bigger picture on what this project does for your property overall, our Home Additions & ADU in Fort Myers page covers the full scope.
Serving Fort Myers, FL - Our Local Coverage Area
We’re based in the Fort Myers 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 Questions About New Detached ADUs in Fort Myers
Five to nine months from signed contract to Certificate of Occupancy. Site prep, soils work, and Lee County plan review consume the first 4 to 8 weeks. Construction runs 12 to 20 weeks depending on foundation type and square footage. Final inspections and punch list add another 2 to 3 weeks. A slab-on-grade studio on a clear lot finishes closer to five months; a raised-foundation one-bedroom in a flood zone with an HOA review runs closer to nine. Call (844) 638-7249 and we’ll give you a timeline specific to your property.
Yes. A new detached ADU in Fort Myers requires a full building permit from Lee County, plus separate mechanical, electrical, and plumbing trade permits, and in many cases an HOA design-review approval before the county will intake the application. This is a fully permitted residential structure; skipping permits on an ADU in Lee County risks a stop-work order, fines, and an uninsurable unit that can’t be rented legally. Our Home Additions & ADU crew handles every permit and inspection from start to finish.
Sometimes. If your existing panel has enough ampacity headroom for a 60-100A subpanel feed and the main house’s sewer lateral has capacity for the additional fixture units, we can tie in without upgrading the main service. If the panel is maxed out or the sewer line is at capacity, you’ll need a service upgrade or a separate lateral, and that adds $3,000-$8,000. We evaluate this during the site survey and tell you upfront if your existing systems can handle the ADU without modification. No surprises.
Not unless you change the scope. We write fixed-price line-item estimates, and the number on your contract is the number you pay. The only exception is if we open a wall or excavate and find something no one could have seen - a buried debris pit from Ian demolition, a collapsed old septic tank, an underground drain field nobody knew was there. In those rare cases we stop work, document what we found, and present you with a change order for the remediation before we proceed. That’s the only scenario. Our Fort Myers clients have been through enough post-storm surprises; the last thing they need is a contractor who plays games with the price.
Every new detached ADU we build is covered by our 730-Day Done Right Promise - if it’s not done right, we make it right. That’s one of the longest workmanship guarantees in residential construction in Southwest Florida. On top of that, the structural frame, foundation, roofing, and windows carry manufacturer warranties from brands like GAF, Andersen, and James Hardie. Your ADU is built to last and backed in writing, with a live person answering our phones 24/7 if you ever need us.
Get a Free On-Site Estimate for Your Fort Myers ADU
If you’re planning a new detached ADU in Fort Myers, the next step is a no-cost on-site walkthrough. We’ll measure your lot, check setbacks and flood zone status, talk through your floor-plan ideas, and put a fixed-price written estimate in your hands - no obligation, no pressure. Every estimate is line-item specific so you see exactly where the dollars go. Call (844) 638-7249 to schedule yours. Estimates are free, and a real person answers the phone.
Written by Derek Hollenbeck, Owner at Groundwork Construction Co., building in Fort Myers with fixed pricing and a 730-Day Done Right Promise.