What a New Detached ADU in Lely Resort Really Costs and What to Expect
A new detached ADU in Lely Resort typically runs between $90,000 and $220,000, with most build-ready backyard sites falling in the $120,000-$160,000 range once plans, permits, and finish materials are locked in. That’s for a code-compliant, hurricane-rated accessory dwelling unit with its own utility connections and foundation, built from the ground up on your property. We’re talking a real second structure here, not a prefab shed with drywall, and the timeline from first stake to final inspection usually spans six to nine months once permitting clears. Call (844) 638-7249 when you’re ready to walk your lot and get an actual number tied to your specific site conditions.
How We Take a New Detached ADU From Paper to Move-In Ready
The process is methodical and transparent, with clear decision points so you’re never wondering what happens next. Here’s what the build sequence actually looks like on a Lely Resort lot.
1. Site walk, survey, and feasibility (Weeks 1-3)
We start with a boots-on-the-ground visit to your property. Derek or one of our senior project leads walks the backyard with you and a survey crew to map setbacks, easements, and the high-water-table realities that come with building on Collier County’s coastal plain. Within the first week we confirm whether your lot can physically accommodate a detached ADU under Lely Resort’s Architectural Review Board (ARB) guidelines, then pull a boundary and topo survey. This is where we flag anything that will add cost: utility trenching distance, tree-protection zones, or fill requirements if your grade sits low relative to the wet-season water table. You’ll decide on approximate square footage and placement by the end of week three so we can move into design.
2. Architectural plans and ARB submittal (Weeks 4-10)
Our architect drafts a full plan set to Florida Building Code and HVHZ standards, including structural engineering for wind-load requirements specific to this part of Collier County. In parallel, we prepare the Lely Resort ARB submittal package - exterior elevations, roof profile, paint and tile selections from the community’s approved palette, window style, and hardscape details. The ARB review alone can take three to five weeks, and submitting a material that isn’t on the association’s pre-approved list will get the whole package bounced. We handle the dual approval dance from day one so county permitting doesn’t stall behind an HOA stop-work situation. You’ll pick exterior finishes, window orientation, and the basic floor-plan shape during this stage.
3. Permitting and utility coordination (Weeks 11-16)
Once the ARB signs off, we submit the stamped plans to Collier County for building permit review. Because a detached ADU requires separate water, sewer or septic, and electric service drops, we coordinate with Collier County utilities and FPL or LCEC to confirm service capacity and trench routes. This is the phase where a property on the eastern side of Lely Resort, closer to the Everglades fringe, might trigger additional site-drainage or floodplain review depending on the elevation certificate. You’re largely hands-off here; we push the paperwork while you review fixture and interior finish selections with our design consultant.
4. Foundation through dry-in (Weeks 17-30)
We excavate, form, and pour a code-specified concrete slab foundation - engineered for the expansive soil and high-moisture conditions common in this part of southwest Florida. Block walls go up (CBS construction, matching the structural standard of every home in Lely Resort), then trusses, roof sheathing, and the HVHZ-rated underlayment and tile or metal roof system. Impact-rated windows and doors go in, the structure gets wrapped, and we hit “dry-in.” You’ll see the biggest visual leap during this stretch, and we’ll walk the interior with you before drywall to confirm outlet locations, window sensor placement, and any last-minute framing adjustments.
5. Interior finish, MEP trim-out, and final inspections (Weeks 31-38)
Insulation, drywall, paint, flooring, cabinet installation, plumbing and electrical trim, HVAC commissioning - this is the sprint to the finish. Our electrician pulls the final connection from the new service panel, the plumber commissions the water heater and fixture set, and we schedule the sequence of Collier County inspections: structural, MEP rough-in, insulation, and final building. Once we have the certificate of occupancy in hand, you do a walkthrough with Derek, we punch anything that needs attention, and we hand over the keys with the full 730-Day Done Right Promise behind every square inch of the build.
The Decisions That Shape Your Detached ADU
A detached ADU isn’t a one-size-fits-all product, and the choices you make early ripple through the budget and the way the space lives. Here are the main decision points, with honest trade-offs.
- Square footage and layout. A compact 400-square-foot studio keeps costs on the low end; a two-bedroom 800-square-foot unit with a full kitchen pushes toward the upper end. Every additional foot of conditioned space adds foundation, framing, roofing, and finish costs proportionally.
- Foundation type. A standard monolithic slab on grade is the default and most cost-effective. If your lot’s elevation demands stem walls or additional fill to meet flood-plain requirements, the civil work line item rises substantially.
- Roof system. You’ll choose between concrete tile (heavier, longer-lasting, required in some Lely Resort sub-associations by ARB mandate) and standing-seam metal (lighter, excellent in wind, but must match the approved profile if your neighborhood association specifies tile). The tile-upgrade cost is real, but so is its 50-year lifespan in Florida’s salt-laden air.
- Kitchen and bath finish level. Stock cabinetry, laminate countertops, and standard fixtures keep things reasonable. Semi-custom cabinets, quartz or solid-surface counters, and Kohler or Delta plumbing fixtures raise the budget but make the unit feel like a true home rather than a rental afterthought. We help you pick materials from our curated brand portfolio so you’re choosing quality, not gambling on availability.
- Separate HVAC system. A mini-split heat pump is the standard efficient choice for an ADU. A ducted central system adds cost but provides better humidity control and air distribution if the floor plan has multiple rooms - worth considering in southwest Florida’s muggy summers.
- Impact-rated windows and doors. Non-negotiable under HVHZ code. The choice is between aluminum-frame and vinyl-frame impact products, with vinyl giving better thermal performance at a slightly higher material cost. Both meet code; the difference is long-term energy efficiency and condensation resistance in the humid season.
What a New Detached ADU Costs in Lely Resort, FL
Expect to budget $90,000 to $220,000 for a new detached ADU in Lely Resort, with most projects we quote landing between $120,000 and $160,000. The spread isn’t random. Five variables move the number more than anything else.
Site access and utility distance. A backyard with easy side-yard access for equipment and a short trench run to the existing water, sewer, and electric services keeps civil costs low. A tight lot where the ADU sits 80 feet from the nearest tie-in point, requiring hand-digging around mature landscaping, pushes the number up fast.
Square footage. A 400-square-foot studio costs roughly half of what an 800-square-foot one-bedroom with a full kitchen costs. The price per square foot does not scale in a straight line, because permitting, utility service drops, and site prep are largely fixed costs regardless of unit size.
Water-table and soil conditions. Lely Resort sits on the coastal plain with the wet-season water table sometimes just 18 to 24 inches below grade. If your lot requires engineered fill, a stem-wall foundation, or a modified drainage plan to meet Collier County’s site-grading requirements, the foundation line item alone can shift by several thousand dollars.
ARB-required exterior materials. If your sub-association’s approved-product list mandates a specific concrete-tile profile, a certain window style, or a stucco finish with a particular color palette, those requirements lock in material costs that might be higher than what a standard county-permitted project would allow elsewhere.
Interior finish grade. Builder-grade finishes keep the number near the bottom of the range. Mid-grade and semi-custom selections throughout the kitchen and bathroom push toward the middle. Full custom cabinetry, quartz or natural stone counters, and upgraded flooring push toward the top.
Our written proposal includes a line-by-line scope: foundation, framing, roofing, exterior cladding, windows and doors, rough and finish plumbing, rough and finish electrical, HVAC, drywall, paint, flooring, kitchen and bath fixtures, trim, and the full permit-and-inspection package. What it does not include are furnishings, window treatments, landscaping or irrigation, and any upgrades you decide on after the contract is signed. Those are priced and approved separately so the base number you sign off on is the number you can plan around. No change orders hiding in the wings.
What Lely Resort Homes Specifically Do to This Job
Building a detached ADU in Lely Resort means navigating a dual-approval process that simply doesn’t exist in most of Collier County. Nearly every residential lot in Lely Resort falls under both the Collier County building-permit authority and the community’s Architectural Review Board, which maintains a tightly controlled list of approved exterior materials, roof-tile profiles, paint colors, and window elevations by neighborhood sub-association. Submit a county-compliant plan using a roof tile that isn’t on the ARB’s approved product list for your specific phase, and you’ll get a stop-work conflict between the county’s approval and the HOA’s enforcement arm. We see this happen regularly to out-of-area crews who treat the HOA review as a formality. It’s not. It’s the gatekeeper, and we build the ARB submittal package first so the county permit never outruns the community’s architectural standards.
The homes here are almost entirely concrete block stucco construction built between the mid-1990s and the 2010s, and that matters for how we tie a new detached ADU into the existing property. The original CBS structures were built to early HVHZ code iterations; the detached ADU must meet the current, more stringent wind-load and impact-resistance requirements. The connection points between the new foundation, the new utility laterals, and the existing home services have to bridge two code eras without compromising either. On the older-phase lots in Lely Resort, we also encounter original underground electric laterals that were sized for a single-family draw and need upgrading to carry the additional load of a fully conditioned ADU with its own panel - a spec you won’t catch until we pull the service records and do the load calculation.
Then there’s the water. During the summer wet season, the groundwater table on the low-lying lots in Lely Resort rises close to grade. Any excavation for the ADU foundation or utility trenches turns into a water-management exercise. We typically bring in a dewatering pump set and schedule foundation pours during the drier winter window when possible. If your lot sits on the eastern edge of the community, where the land slopes toward the Everglades fringe, we may also need a site-specific drainage plan that routes runoff around the new structure without impacting the neighboring lots. These aren’t complications you’ll read about on a generic ADU page. They’re the day-to-day reality of building in this specific community, and we’ve worked through enough of them that nothing surprises us.
When a homeowner is planning a full property transformation - something that might also involve interior work in the main house - they’ll sometimes ask us to coordinate the ADU build with a Home Additions & ADU in Lely Resort scope so we’re not trenching the backyard twice. It makes sense logistically, and it’s the kind of big-picture planning we walk through on the first site visit. For homeowners refining the interior of the main house while the ADU goes up, we often hear interest in Kitchen Design & Layout in Lely Resort or Backsplash, Tile & Flooring in Lely Resort - those indoor finishes don’t conflict with the backyard build schedule, and bundling the work across our Home Additions & ADU crew keeps things simpler than hiring separate contractors. Every project we do in Lely Resort starts with a straightforward lot walk to figure out what’s actually possible, not what looks good on a brochure.
Serving Lely Resort, FL - Our Local Coverage Area
We’re based in the Lely Resort 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 a New Detached ADU in Lely Resort
From the day we stake the site to the day you get the certificate of occupancy, plan on six to nine months. The biggest variable is the front-end approval sequence: the Lely Resort ARB review adds three to five weeks, and Collier County permit review typically runs four to six weeks depending on volume. The construction itself - foundation through final inspection - takes roughly five to six months for a standard 400-to-800-square-foot unit. Weather delays during the summer rainy season can push the tail end by a week or two. If you’re working against a specific move-in date, call (844) 638-7249 early so we can back-time the schedule for you.
Yes, and this is the single most common surprise for homeowners in Lely Resort. The community’s Architectural Review Board must approve your ADU’s exterior design - roof material and color, exterior paint, window style, and placement on the lot - before Collier County will issue the building permit. We prepare and submit both packages in parallel so the HOA review doesn’t add avoidable weeks to your timeline. A stop-work order from the ARB after the county permit is issued is expensive and entirely preventable with a contractor who knows the community’s submission process.
We pull every permit for every job. A new detached ADU requires a building permit, an electrical permit, a plumbing permit, and often a separate site-drainage or right-of-way permit depending on where your utility connections come in. Our permit coordinator manages the whole stack from submittal to final sign-off, and every inspection gets scheduled and met by the crew lead who built the work. The 730-Day Done Right Promise covers the entire build, and that starts with a properly permitted project that passes every inspection the first time.
Not from our side, unless you change the scope. The number on your written proposal is the number you pay for the work described in that proposal. If we hit unexpected subsurface conditions - a buried debris pit from the original community build-out, for instance - we document it, show you what’s there, and give you a separate line-item price to address it before any work proceeds. We don’t bury change orders in the fine print, and we don’t show up mid-job asking for more money because we underbid. Upfront pricing means exactly that.
Every component of the build is covered by our 730-Day Done Right Promise. If something isn’t right - a drywall crack, a door that doesn’t latch properly two monsoons later, a plumbing fitting that weeps - we come back and make it right at no cost to you. That’s two full years of coverage, which is among the longest workmanship guarantees you’ll find in residential construction in southwest Florida. Manufacturer warranties on the roof system, windows, appliances, and HVAC equipment run separately and typically extend well beyond our labor coverage period. We walk you through every warranty document at the final walkthrough so you know exactly who covers what and for how long.
Ready to See What Fits on Your Lot?
A new detached ADU in Lely Resort is a serious build, and the best way to get a real number is to have us walk the property. We’ll measure setbacks, check utility access, talk through the ARB requirements for your specific sub-association, and give you a written, line-item estimate that accounts for your lot’s actual conditions - not a guess over the phone. Call (844) 638-7249 to schedule your free on-site estimate. The call goes to a live person, any time of day, and we’ll have someone on your property within the week.
Written by Derek Hollenbeck, Owner at Groundwork Construction Co., bringing straight answers and transparent pricing to Lely Resort homeowners.