What a Junior ADU & Interior Conversion Actually Looks Like in Iona
A junior ADU and interior conversion in Iona typically ranges from $45,000 to $130,000 and transforms existing square footage inside your home into a fully self-contained living unit with its own entrance, kitchenette, and bathroom. Most projects take 8 to 14 weeks depending on whether you’re converting a ground-floor bedroom suite, an attached garage, or a large bonus room, and whether plumbing stacks and electrical panels need to be relocated. Call (844) 638-7249 for a free on-site estimate with a written scope of work - we’ll walk the space with you and tell you exactly what’s possible before you spend a dime.
How We Build a Junior ADU & Interior Conversion, Step by Step
The sequence matters because each stage unlocks the next, and surprises caught early don’t derail a job. Here’s how it goes on a typical Iona home.
Days 1-3: Demolition and Discovery
We strip walls, flooring, and any existing fixtures back to the studs and slab. This is when we confirm what’s actually behind the drywall - the age and condition of wiring, whether the cast-iron drain pipes (common in 1970s-era canal homes) have corroded, and where the joists actually run. You’ll decide here whether to keep the existing window openings or enlarge them for egress, which becomes a life-safety requirement once the room becomes a sleeping space. Demolition typically takes two to three days.
Days 4-14: Rough-In and Structural Modifications
Electrical, plumbing, and any framing changes happen now. If you’re adding a kitchenette with a sink and a two-burner cooktop, we’ll need to run new supply lines and a drain stack - this is the single biggest cost variable in a junior ADU conversion. Relocating plumbing across a slab-on-grade floor in Iona means cutting concrete, which adds both time and dollars. We rough in the subpanel if the existing service can’t handle the additional load, and we frame any new interior walls that define the kitchenette, bathroom, and closet zones. Pass rough inspection, and we move on.
Days 15-30: Insulation, Drywall, and Waterproofing
Closed-cell spray foam goes into exterior walls for both R-value and moisture resistance - critical in Iona’s humid coastal climate. We hang, tape, and float drywall, then install cement board and a waterproof membrane in the wet areas. During this stage you’ll confirm your finish selections: cabinet door style, countertop material, flooring, and tile. Lead times on semi-custom cabinetry run two to four weeks, so we order early. Drywall finishing alone takes about five days with drying time.
Days 31-50: Finishes and Fixtures
Cabinetry, countertops, plumbing fixtures, lighting, and flooring all go in. This is where the space starts looking like a real apartment. We trim out doors and windows, install the baseboards, and mount the appliances. If your junior ADU has a separate exterior entrance - which most Iona homeowners want for rental privacy - we’ll frame and install an exterior-grade door rated for wind-load requirements per Lee County code. Final paint and punch-list walkthrough happens here.
Days 51-Final: Inspections and Turnover
Lee County requires a final building inspection, and if we touched electrical or plumbing, those trades get their own sign-offs too. We handle every inspection - you don’t need to be on site. Once the county signs off, we do a detailed walkthrough with you, demonstrate every system, and hand over a binder with all warranties and material specs. From first cut to key handoff, expect to be in the unit within 10 to 14 weeks.
The Decisions You’ll Actually Make During a Junior ADU & Interior Conversion
Every job involves trade-offs. Here are the choices that shape the outcome and the budget.
- Kitchenette configuration. A wet bar with a mini-fridge and microwave keeps costs low. A full kitchenette with a sink, two-burner electric cooktop, undercounter refrigerator, and compact dishwasher pushes the budget toward the upper range. Iona homeowners renting the unit seasonally tend to want full cooking capability.
- Bathroom scope. A pre-existing half-bath needs less work than converting a closet into a three-piece bath with a shower. If you’re adding a shower where no drain existed, expect slab-cutting and a higher permit fee. We’ll give you the cost difference before we start cutting.
- Flooring material. Luxury vinyl plank handles Iona’s humidity and occasional track-in from canal-side foot traffic far better than engineered wood. Porcelain tile costs more up front but lasts longer. We stock samples from brands like Belgard for interior porcelain tile that holds up to wet feet and sandy floors.
- Separate entrance. Adding a private exterior door requires cutting through a concrete-block wall and installing a properly flashed, wind-rated door assembly. It adds cost but makes the unit truly independent - rentable, lockable, and code-compliant as a dwelling unit. We recommend impact-rated door systems for this application.
- Electrical capacity. An older Iona home with a 100-amp panel may need a subpanel or a service upgrade to 200 amps to support a kitchenette and separate HVAC. That’s a multi-thousand-dollar decision we’ll flag in the estimate, not spring on you mid-job.
What a Junior ADU & Interior Conversion Costs in Iona, FL
A junior ADU and interior conversion in Iona runs $45,000 to $130,000. The low end reflects a straightforward conversion of an existing bedroom suite with a bathroom already in place, minimal plumbing relocation, and off-the-shelf finishes. The high end covers a ground-up transformation of an attached garage or large bonus room that requires cutting the slab for a new bathroom group, upgrading the electrical panel, adding a private entrance, and installing semi-custom cabinetry with stone countertops.
The variables that push the number: how far the new wet wall sits from the existing drain stack, whether the concrete slab needs trenching, the condition of the existing electrical panel, and the door and window ratings required by Lee County’s wind-load provisions. We write line-item estimates so you see exactly what each choice costs - no round numbers, no allowances that balloon later. The number you see is the number you pay, and every estimate includes the permit fees, the material specs, and the timeline.
When you call (844) 638-7249, we’ll schedule a free on-site walkthrough. You’ll get a written estimate within a few days that breaks down every line item. No pressure, no same-day closing pitch - just numbers you can take to your lender or HOA board.
What Iona Homes Specifically Do to a Junior ADU & Interior Conversion
Iona sits in the bull’s-eye of Hurricane Ian’s 2022 storm-surge corridor along the Caloosahatchee River estuary, and nearly every interior conversion we do here runs straight into Lee County’s post-Ian compliance reality. Most of the housing stock is 1970s-to-1990s concrete-block construction on slab, much of it on finger canals with original floor elevations that now fall below current Base Flood Elevation requirements. That means a project that triggers the “substantial improvement” threshold - repairs or upgrades exceeding 50% of the assessed structure value - can force the entire home to be elevated, which is a different conversation entirely. We check the county’s substantial-improvement calculation before we design anything, so you know where you stand.
Because Iona is unincorporated Lee County, every permit runs through the Lee County Building Department, not a municipal office. Post-Ian, the volume of substantial-improvement reviews has created a permitting backlog that catches out-of-area contractors off guard. We’ve been navigating that system for years and know which drawings and calculations the reviewers want to see on the first submission. Many canal-front lots that were rebuilt or lifted post-Ian now require seawall certification before the county issues a building permit, which can add two to three weeks if a marine engineer isn’t engaged early. We bring that engineer into the project on day one when the property warrants it. This is the kind of local knowledge that keeps a junior ADU conversion on schedule instead of stuck in review - and it’s something a generic contractor working across five counties simply won’t flag for you.
If your junior ADU is part of a larger vision, see our Home Additions & ADU in Iona page for the full scope of what’s possible on your lot. Homeowners with Iona canal-front properties often pair an interior ADU conversion with Small & Partial Kitchen Remodels in Iona or a Kitchen Design & Layout in Iona project in the main house while the construction crew is already on site - it saves on mobilization costs and condenses the disruption into one timeline. Our Home Additions & ADU crew handles the whole project from foundation to finish line, so you’re not juggling separate subs for the conversion and any concurrent work in the main house.
During southwest Florida’s late-summer tropical storm season, any structural work involving open rooflines or exposed concrete on an Iona job site must account for afternoon thunderstorms that can arrive in under 30 minutes and saturate freshly poured concrete or exposed framing. We compress our open-structure phases into the October-to-May dry window whenever possible, and we tarp and protect aggressively when the forecast turns. That seasonal reality shortens the reliable construction calendar in Iona by a solid four months a year, and it’s why we recommend booking a fall or winter start date if your conversion involves cutting the exterior envelope.
Serving Iona, FL - Our Local Coverage Area
We’re based in the Iona 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 - Junior ADU & Interior Conversion in Iona
Most projects finish in 8 to 14 weeks. A straightforward bedroom-suite conversion with an existing bathroom stays on the shorter end. An attached-garage conversion requiring slab-cutting, new plumbing, and a separate entrance takes the full timeline. Lee County’s inspection scheduling can add a week or two during peak building season, but we build that buffer into the schedule from the start.
Yes. Any interior conversion that adds a kitchenette, bathroom, or sleeping quarters requires a building permit from Lee County, along with electrical and plumbing permits where those trades are modified. We pull every permit, schedule every inspection, and carry the liability. An unpermitted junior ADU won’t pass an insurance inspection and can jeopardize a claim - especially in Iona, where post-Ian insurers are scrutinizing any unpermitted living space.
Sometimes. If the room you’re converting already shares a wall with an existing bathroom and the drain stack is on that wall, we can often tie into it without cutting the slab. That keeps the cost toward the lower end of the range. If the nearest drain line is 20 feet away and runs under a concrete floor, the price moves up. We’ll tell you which scenario you’re in during the walkthrough. Call (844) 638-7249 and we’ll come take a look.
A junior ADU is built within the existing footprint of the primary home and is typically capped at 500 square feet. A full detached ADU is a separate structure with its own foundation, and in Iona that often triggers the full FEMA flood-elevation review. The junior ADU path is faster, less expensive, and avoids the site-prep and foundation costs that push a detached ADU to $90,000-$220,000. For most Iona homeowners on canal lots with limited buildable yard space, the interior conversion is the more practical route.
It does. Every interior conversion we build is covered by our 730-Day Done Right Promise - if it isn’t done right, we make it right, full stop. That covers workmanship on framing, drywall, flooring, cabinetry installation, plumbing connections, and electrical work. Material warranties from manufacturers like the cabinet and fixture brands run separately and we document every one in your turnover binder.
Get a Free Estimate for Your Junior ADU & Interior Conversion in Iona
We’ll walk your space, talk through what’s realistic given your home’s layout and Lee County’s requirements, and hand you a written line-item estimate - usually within a few days. No round numbers, no allowances that change later. Call (844) 638-7249 to schedule your free on-site estimate. You’ll speak with a live person, and we’ll have a background-checked, uniformed estimator at your door ready to answer every question you have about building a junior ADU in Iona. Built to last, backed in writing.
Written by Derek Hollenbeck, Owner at Groundwork Construction Co., serving Iona, FL.