ADU Construction Cost - Plans, Permits & Build, One Fixed Price

How Much Does ADU Construction Cost in Jacksonville?

ADU construction in Jacksonville typically costs between $90,000 and $220,000, with most families landing between $130,000 and $180,000 for a detached one-bedroom unit of roughly 600 to 800 square feet. Those numbers include foundation work, framing, electrical, plumbing, HVAC, drywall, flooring, fixtures, appliances, and finish carpentry from a licensed general contractor. A garage conversion runs lower, usually $30,000 to $80,000, because the shell already exists.

Those ranges reflect what we’re seeing across Duval County in 2026, from Riverside and Avondale infill lots to Mandarin and Bartram Park neighborhoods. Before we go further, you should know one thing about how we work: at Elmstead Remodeling Jacksonville, you’ll get a written price before any work starts. No allowances that drift. No “we’ll see how it goes.” The number on paper is the number you plan around.

If you’re considering an ADU for an aging parent, a returning adult child, or rental income, this guide walks through every line item so you can see where the money goes. And if you want a specific number for your lot and your plans, call (904) 643-6243 to schedule a free estimate.

ADU Construction Cost Breakdown (2026)

Here’s how a typical detached ADU budget breaks down across Jacksonville. These are contractor-level numbers, meaning they include labor, materials, permits, and project management, not just what you’d pay for materials at a Home Depot on Blanding Boulevard.

Line Item	Typical Range (Jacksonville, 2026)
Site preparation & foundation	$8,000 – $22,000
Framing & structural	$14,000 – $32,000
Electrical rough-in & finish	$6,000 – $14,000
Plumbing rough-in & fixtures	$5,000 – $13,000
HVAC (mini-split or ducted)	$4,000 – $10,000
Insulation & drywall	$5,000 – $10,000
Flooring	$3,000 – $8,000
Kitchenette (cabinets, countertop, sink)	$8,000 – $20,000
Bathroom (shower, vanity, toilet, tile)	$9,000 – $20,000
Interior & exterior doors	$2,000 – $6,000
Windows	$2,500 – $7,000
Exterior siding & roofing	$9,000 – $22,000
Paint & finish work	$3,500 – $9,000
Permits & inspections	$2,500 – $8,000
Contractor overhead & project management	$8,000 – $19,000
Total (detached ADU)	$90,000 – $220,000

Two or three line items above deserve a closer look, because they’re the ones that surprise people.

Permits in Jacksonville aren’t a formality. The city’s Building Inspection Division charges plan review fees, impact fees, and inspection fees that climb based on square footage and whether you’re adding a separate meter. Expect the permit process to take 4 to 10 weeks depending on your neighborhood and whether you’re in a historic district. If you’re in Springfield or Riverside-Avondale, the local overlay adds a design review step that can extend timelines and add $1,500 to $4,000 in consultant fees.

Site preparation varies block by block. Some lots in San Marco sit on high, dry ground that needs almost no prep. Others in Arlington or along the Arlington River sit on soil that requires engineered fill, compaction, or even helical piers, which can add $6,000 to $15,000 before a single wall goes up. We’ve seen two identical ADU plans come in $18,000 apart purely because of what was under the grass.

Detached vs. attached changes the number more than most families expect. A detached ADU needs its own foundation, its own four exterior walls, and its own roof line, which drives the framing and exterior budget. An attached addition, or a garage conversion at ADU Construction in Jacksonville rates of $30,000 to $80,000, reuses walls, roof, and sometimes even the electrical panel, which is why it lands lower. That link walks through the difference, but the short version: if you have an underused garage, starting there usually saves $40,000 to $90,000.

What Affects ADU Construction Pricing in Jacksonville

Five factors move the number more than anything else in this market.

• Foundation type and soil conditions. Jacksonville sits on a mix of sand, clay, and in some pockets, muck. A standard slab on grade in Mandarin might cost $6,000, while the same footprint in a lower-lying part of San Jose Boulevard could need $14,000 in soil correction and deeper footings. We can’t tell you which you have until we test it, which is why our written price always follows a site visit, never precedes it.
• Attached, detached, or conversion. Detached runs $90,000 to $220,000. Attached additions run $45,000 to $130,000. Garage conversions run $30,000 to $80,000. That’s a $50,000 swing between the low end of a conversion and the low end of a detached build, and it’s the first decision that locks your budget in.
• Finish level inside the unit. Stock cabinets from a big-box store land at $3,000 for a kitchenette; KraftMaid or Wellborn cabinetry, which we install by default on our ADU projects, lands at $7,000 to $12,000. Same footprint. The difference is in drawer hardware, paint curing, wood species, and a warranty you can actually claim. Countertops follow the same pattern: laminate at $800, Cambria or Silestone quartz at $2,500 to $5,000.
• Separate utility meters vs. tied to the main house. Adding a separate electrical meter and water line typically costs $4,000 to $9,000 in Duval County but pays for itself if you’re renting the unit, because you can charge tenants directly. If it’s for family, staying on the main panel saves the money up front but adds load that older panels in 1950s-era Arlington or San Marco homes sometimes can’t handle without a $2,500 to $5,000 panel upgrade.
• Historic district requirements. If your home is in Riverside, Avondale, or Springfield, the Jacksonville Historic Preservation Commission may review your plans. Exterior materials, rooflines, window styles, and even paint colors get scrutinized. The review itself doesn’t cost much, but compliance can add $5,000 to $15,000 to the total when you’re required to match period-correct windows, siding, or roof profiles.
• Access to the build site. If your backyard is fenced with a six-foot privacy fence and a narrow gate, materials get walked in by hand or brought over the fence in smaller loads. If the lot has side-yard access and room for a dumpster and a skid steer, the crew moves faster. The labor difference can be $3,000 to $8,000. We always walk the access path before quoting, and the written price accounts for how the crew will actually get materials in and debris out.

How to Save on ADU Construction

Savings in ADU construction come from decisions you make before the first permit is pulled, not from cutting corners mid-build. Here’s where Jacksonville families find real money without sacrificing the parts that matter.

Start with a garage conversion if you have one. The most expensive parts of a detached ADU are the foundation, four walls, and a roof. A garage already has three of those. At $30,000 to $80,000, a conversion in neighborhoods like Murray Hill or San Marco delivers rentable square footage for roughly half the price of new construction. You give up garage storage, but many families add a shed for $2,000 to $4,000 and still come out ahead.

Keep the footprint under 600 square feet. Jacksonville’s building and zoning code changes requirements at certain square footage thresholds, and every square foot adds roughly $150 to $250 in hard costs. A 550-square-foot one-bedroom with a kitchenette and full bath meets the needs of most renters or in-laws. The difference between 550 and 800 square feet is often $35,000 to $50,000 on the final number.

Choose a mini-split over ducted HVAC. A ducted system for an ADU runs $8,000 to $14,000 by the time you account for ductwork, a handler, a condenser, and electrical. A quality mini-split from a name like Mitsubishi or Daikin runs $4,000 to $7,000 installed and handles Jacksonville’s heat and humidity well when sized correctly. For a one-bedroom unit, it’s usually the right call both up front and on the monthly JEA bill.

Pick finishes from a curated list, not à la carte. Custom tile from a designer showroom in Avondale can run $30 per square foot. Large-format porcelain from a standard line runs $6 to $10 and wears the same in a rental or a mother-in-law suite. We keep a finish library of named products, Kohler and Moen fixtures, Cambria and Silestone countertops, KraftMaid and Wellborn cabinets, so you can pick from proven options without paying for showroom markup. The written price we give you reflects those selections.

Ask about the 365-Day Done Right Promise before you sign. This doesn’t lower the price up front, but it changes what the price means. If something isn’t done right after the job is complete, we make it right. A warranty that actually gets honored is worth more than a $3,000 discount from a contractor who won’t return calls in month two. Our promise is stamped on every project, and Graham Stein, who leads Elmstead Remodeling Jacksonville, personally reviews every Done Right claim that comes through.

You can also call (904) 643-6243 for a free estimate. It costs nothing, and you’ll have a written number you can compare against any other quote in Jacksonville.

ADU Construction in Jacksonville: What the Process Looks Like

Families often ask us what happens between signing the contract and turning the key. Here’s the actual sequence, with the timelines we’re seeing in Duval County in 2026.

1. Site visit and measurements. We walk the lot, check access, test soil where needed, and look at the existing electrical panel and water service. This visit is free, and it’s how we can give you a written price instead of a guess.
2. Design and architectural drawings. If you don’t have plans, we work with a local draftsperson or architect who knows Jacksonville’s zoning and building code. Drafting costs $2,500 to $6,000 depending on complexity and whether the structure needs engineering review.
3. Permit application. We submit to the city’s Building Inspection Division. Plan review takes 3 to 8 weeks. Historic districts add time. Impact fees and permit fees are included in the written price we gave you, not billed as a surprise later.
4. Site prep and foundation. This is where soil conditions surface. We order a compaction test if the lot has been recently disturbed, and we bring in engineered fill where the soil won’t bear the weight. This phase runs 1 to 3 weeks.
5. Framing, roofing, and exterior. The structure goes up, the roof goes on, and the exterior gets house wrap and siding. You’ll see the shape of the unit in about 3 to 5 weeks.
6. Rough-in: electrical, plumbing, HVAC. Inspectors come through at this point. We schedule the inspections and handle any corrections. This phase runs 2 to 4 weeks.
7. Insulation, drywall, and finishes. Floors go in, cabinets go in, paint goes on, fixtures get set. This is the longest visible phase, usually 4 to 7 weeks.
8. Final inspection and clean-up. The city signs off, and then we do something most contractors don’t: we take a photo of the clean-up before the crew leaves. You get that photo. It’s included on every project, and it’s our proof that the home was left right.

Total timeline for a detached ADU in Jacksonville: 4 to 8 months from contract to final inspection. Garage conversions run 2 to 4 months. If you’re planning around a lease end or a family member’s move date, build that window into your calendar.

Jacksonville-Specific Factors Other Guides Don’t Mention

Most ADU cost guides are written for a national audience and miss the things that actually move the number in Duval County. Here are the ones we deal with every month.

Flood zones and elevation certificates

Parts of Jacksonville sit in FEMA flood zones, particularly along the St. Johns River, the Ortega River drainage, and some older neighborhoods in the urban core. If your lot is in a flood zone, the ADU’s finished floor may need to be elevated, which adds $6,000 to $18,000 depending on how high and whether you need fill, piers, or a raised foundation. We check FEMA maps before quoting, and if you need an elevation certificate or floodproofing design, that’s in the written price, not an add-on.

Impact-resistant windows and wind load

Jacksonville sits on the edge of the hurricane zone, and the building code requires wind-rated openings. Standard impact windows for an ADU run $2,500 to $7,000 installed. If you’re replacing windows elsewhere in the home, window replacement costs in Jacksonville run $4,500 to $15,000, and impact window installation runs $8,000 to $25,000 for a whole home. For the ADU itself, we spec windows rated for the wind zone without charging custom-order premiums.

Termite treatment and soil treatment

Florida’s termite pressure is real, and any new foundation needs a termite barrier. That’s $800 to $2,500 depending on the treatment type and the size of the slab. We include it on every ADU foundation, because the state building code requires it and because skipping it is a false economy in this climate. If you’re building in an older part of town where termite damage has been documented on the block, we might recommend a more aggressive treatment, and that’s in the written price too.

JEA service and separate meter requirements

If the ADU has its own meter, JEA charges a service connection fee and may require a new drop from the pole or a separate water tap. Those utility fees run $2,000 to $6,000. If you keep the ADU on the main panel, you skip that cost but you’ll need load calculations to prove the existing panel can handle it. Homes built before 1980 in neighborhoods like Lakewood or Riverside sometimes have 100-amp panels that need a $2,500 to $5,000 upgrade before the city will sign off.

ADU Construction vs. Other Project Types

If you’re weighing an ADU against other ways to add space, here’s how the numbers compare in Jacksonville.

• Home addition: $45,000 to $130,000. An attached addition costs less per square foot than a detached ADU because it shares a wall and utilities with the existing house. But it doesn’t give you separate rental income.
• Garage conversion: $30,000 to $80,000. The cheapest path to a rentable unit, assuming your garage is in good structural shape. We inspect the slab, walls, and roof before quoting, because some older Jacksonville garages have slab cracks or termite damage that change the number.
• Kitchen remodel: $14,000 to $45,000, with small kitchens at $9,000 to $20,000. If the ADU includes a kitchenette, cabinet installation runs $4,000 to $13,000 and countertop installation runs $2,000 to $6,500.
• Bathroom remodel: $9,000 to $28,000. The ADU’s bathroom will feel a lot like a small bathroom remodel, which runs $5,000 to $12,000 in this market, though the plumbing rough-in before drywall is a separate cost in new construction.
• Roof replacement: $8,000 to $20,000. If you’re adding a detached ADU, the roof is part of the ADU budget. If you’re converting a garage, the existing roof might need replacement at the same time, and that’s a separate line item we’ll show you in writing.

Is an ADU a Good Investment in Jacksonville in 2026?

That depends on your lot, your zoning, and your reason for building. Here’s the honest version we give every family that asks.

For rental income: A one-bedroom ADU in a desirable neighborhood near San Marco, Riverside, or the beaches rents for $1,200 to $1,800 per month in 2026. At a $160,000 build cost, that’s a 9% to 13% gross annual return, before property taxes and utilities go up. If you finance with a HELOC or construction loan, the payment on a $160,000 loan at 7% is roughly $1,100 per month, so the rent covers the note in most in-town neighborhoods. In further out parts of the Westside or Northside, rents run $800 to $1,200, which changes the math.

For family use: The return isn’t financial, but the cost compares well against assisted living. A modest assisted living facility in Jacksonville runs $4,000 to $6,500 per month in 2026. A $150,000 ADU with no monthly facility fee pays for itself in about three years, and the family member stays on your property. Whether that’s the right arrangement is a family decision, but the numbers are worth looking at.

For resale value: ADUs are still uncommon enough in Jacksonville that comps are tricky. An appraiser will look at the added square footage and give you credit, but an ADU doesn’t add $200,000 in market value just because it cost $200,000 to build. Plan for the ADU to recoup 60% to 80% of its cost in resale value today. That number should improve as more Jacksonville families build them and comps become more common.

Common ADU Construction Cost Questions, Answered

How much does a 600-square-foot ADU cost in Jacksonville?

A 600-square-foot detached ADU in Jacksonville runs $110,000 to $175,000 in 2026, including permits, foundation, framing, utilities, kitchenette, bathroom, and finishes. The variance comes from soil conditions, finish level, and whether the unit has a separate meter. Start from that range and refine with a site visit. Our estimates are free, and the written price you get from (904) 643-6243 is the number you’ll pay, not a starting point.

Is it cheaper to build an ADU or convert a garage in Jacksonville?

A garage conversion is almost always cheaper: $30,000 to $80,000 versus $90,000 to $220,000 for a detached ADU. The savings come from reusing the foundation, walls, and roof. A conversion might not be viable if the existing garage has termite damage, a cracked slab, or is too small for a legal dwelling unit, so we’d inspect it before recommending either path. Call (904) 643-6243 and we’ll walk the garage with you.

Does Jacksonville allow ADUs in residential neighborhoods?

Yes, but with zoning conditions. Jacksonville allows ADUs, described in the zoning code as “accessory dwelling units,” in most residential zones, subject to setbacks, height limits, and sometimes owner-occupancy requirements. Some neighborhoods with historic overlays add design review. We check your property’s zoning and overlays before quoting, and if your lot can’t legally support an ADU, we’ll tell you before you spend a dollar. That’s part of the job, and it doesn’t cost you anything to ask.

How long does ADU construction take in Jacksonville?

Plan on 4 to 8 months for a detached ADU and 2 to 4 months for a garage conversion. The biggest variables are city permit review time (3 to 8 weeks currently) and weather, because July and August thunderstorms slow exterior work. We give you a written schedule alongside the written price, and we protect floors and finished surfaces with drop cloths and shoe covers throughout, so the daily disruption to your family stays minimal even while the crew is on site.

Does an ADU increase property taxes in Jacksonville?

Yes. The Duval County Property Appraiser will reassess your property after the ADU is permitted and completed, and your taxable value will rise by roughly the market value the ADU adds, typically 60% to 80% of the construction cost. On a $160,000 ADU, expect your annual property tax bill to rise by roughly $1,500 to $2,500 depending on your millage rate and exemptions. If the ADU is for a qualifying senior family member, ask your tax advisor whether any exemption applies to your situation.

Why Jacksonville Families Build ADUs With Elmstead Remodeling

We’re a Cedarwell company, and every Elmstead Remodeling Jacksonville project, including ADU construction, follows the Cedarwell Care Promise. That promise is not a slogan on a website. It’s a list of behaviors the crew follows on your property.

The crew puts shoe covers on before entering your home. Drop cloths go down on any floor surface that a ladder, tool bag, or material cart might touch. Quiet tools come out during nap hours and school hours when possible, which matters when you have a sleeping toddler and an ADU going up in the backyard. Pet-safe product choices are made where there is a choice, because the family’s dog doesn’t know to avoid a wet floor or a drying surface. We ask before moving anything, which means your patio furniture, your hose reel, and your kids’ toys don’t get relocated without a conversation.

The C.A.R.E. values are how we keep that promise: Clean up like it is our own home, Ask before we move or touch anything, Respect the family’s time and quiet hours, and Explain the price before the work. That last one is the one families mention most. A written price before any work starts means you’ll never get a call halfway through the foundation saying the number went up.

Our cabinet partners include KraftMaid and Wellborn. Countertops come from Cambria, Silestone, and Caesarstone. Fixtures come from Kohler, Moen, and Grohe. Exteriors use James Hardie and GAF products. Those are brands you can research by name, and their manufacturer warranties travel with the finished project. If you ever need to make a claim, you have a paper trail that starts with a real brand and ends with a real phone number.

And when the job is done, the 365-Day Done Right Promise takes over. If it’s not done right, we make it right. That’s the longest-standing post-project commitment in our service area, and Graham Stein, who leads Elmstead Remodeling Jacksonville, stands behind it personally on every project we complete.

Phones are answered by a live person 24/7 at (904) 643-6243. Not a voicemail box. Not an automated system. If you call at 11 p.m. to ask about ADU cost per square foot, a person answers. If you call during nap time, the same person answers and can schedule around your family’s rhythm.

FAQs – ADU Construction Cost

What is the cheapest ADU option in Jacksonville?

The cheapest legal ADU option in Jacksonville is a garage conversion at $30,000 to $80,000, followed by a small attached addition at $45,000 to $90,000. A detached ADU starts around $90,000. The cheapest option that still qualifies as a dwelling unit, with a bathroom and kitchenette, is typically a 400 to 500-square-foot conversion. Call (904) 643-6243 for a free estimate on your specific garage or lot.

How much does ADU plumbing cost in Jacksonville?

ADU plumbing, including rough-in, fixtures, a water heater, and connection to the main line or a new tap, runs $5,000 to $13,000 in Jacksonville. A separate water meter from JEA adds $2,000 to $4,000. If the ADU bathroom includes a walk-in shower, that’s $4,500 to $12,000 as part of a remodel, though in new construction the shower is part of the rough-in and finish plumbing budget. Estimates are free at (904) 643-6243.

What is the return on an ADU in Jacksonville?

A detached ADU in Jacksonville typically recoups 60% to 80% of its construction cost in immediate resale value, and if rented, generates a gross annual return of 9% to 13% based on 2026 rents of $1,200 to $1,800 per month in in-town neighborhoods. The financial picture depends on your neighborhood, your property taxes, and whether you’re financing. We can’t give financial advice, but we can give you the construction number that feeds your own calculations.

Can you build an ADU on a small Jacksonville lot?

Sometimes. Jacksonville’s zoning code sets minimum lot size, setback, and lot coverage rules that vary by zone. A narrow lot in Springfield or Riverside may not support a detached ADU but could support a garage conversion or a second-story addition. We check your lot’s zoning, setbacks, and overlay district before quoting. The written price you get reflects what’s actually buildable on your property, not a generic number.

Do you need a permit for an ADU in Jacksonville?

Yes. ADUs require building permits, and depending on the scope, electrical, plumbing, mechanical, and sometimes stormwater permits from the city of Jacksonville’s Building Inspection Division. Plan review runs 3 to 8 weeks and costs $2,500 to $8,000 including impact fees. Building without a permit can result in fines, a stop-work order, and a structure that can’t be insured or rented. We handle the permit package as part of the written price.

Ready to Get a Written Price for Your Jacksonville ADU?

A free estimate from Elmstead Remodeling Jacksonville means we walk your lot, check your zoning, look at the soil and the access path, and then hand you a written price before any work starts. Not a range. Not a starting point. The number.

Call (904) 643-6243 to schedule a site visit. A live person answers 24/7, and the visit is free. If you’re still in the research phase, start with our home page to see how we work across Jacksonville, or the ADU Construction in Jacksonville service page for more detail on the build process itself.

Written by Graham Stein, Owner at Elmstead Remodeling Jacksonville, serving Jacksonville since 2005.

Pricing reflects the Jacksonville market as of 2026. Elmstead Remodeling Jacksonville offers free estimates – call (904) 643-6243.