Complete 2026 cost breakdown: construction, permits, financing, and expected rental ROI.
Calculate your Jacksonville ADU cost →Building an ADU in Jacksonville costs between $150,000-$300,000 for new construction, with per-square-foot costs averaging $150-$360. These figures include design, permitting, site preparation, and construction. The most affordable option is a garage conversion at $65,000-$130,000, while prefab/modular ADUs fall in between at $125,000-$200,000.
| Cost Category | Estimated Range |
|---|---|
| Architectural Plans | $3,000 – $15,000 |
| Permits & Fees | Building permit fees are set by Ordinance Code Chapter 320 on the gross floor area under roof, plus separate electrical, plumbing and mechanical permit fees; the city publishes no ADU-specific figure, so price it in JaxEPICS or with the Building Inspection Division (904-255-8500). |
| Impact Fees | Jacksonville's transportation Mobility Fee (Ordinance Code Ch. 655) is charged on new development that adds trips and must be paid before the vertical building permit issues; exemptions are listed in Sec. 655.109 and de minimis uses in Sec. 655.108. Ask the Concurrency and Mobility Management System Office (CMMSO@coj.net) whether a single ADU is exempt or de minimis before budgeting, and ask JEA about connection charges if the unit gets its own water or sewer service. |
| Site Prep & Foundation | $10,000 – $35,000 |
| Framing & Structure | $15,000 – $45,000 |
| Plumbing | $8,000 – $20,000 |
| Electrical | $5,000 – $15,000 |
| HVAC | $3,000 – $8,000 |
| Interior Finishes | $15,000 – $40,000 |
Quotes for the same ADU commonly vary 20–40% between builders. We pass your request to up to 5 local builders serving Jacksonville, where we have them — free, no obligation.
Get Jacksonville builder quotes →Permit fees in Jacksonville are Building permit fees are set by Ordinance Code Chapter 320 on the gross floor area under roof, plus separate electrical, plumbing and mechanical permit fees; the city publishes no ADU-specific figure, so price it in JaxEPICS or with the Building Inspection Division (904-255-8500).. The review timeline is The city publishes no review clock for residential plan review; JaxEPICS returns comments once every discipline has reviewed the set. A permit expires after 180 days without work (Building Inspection Division FAQ)., with plan check: Electronic plan review in JaxEPICS by every discipline, including the fire marshal; the Florida Building Code 8th Edition (2023) and NEC 2020 apply. Lots in a FEMA flood zone are also reviewed by Development Services' Review Group.. Impact fees are Jacksonville's transportation Mobility Fee (Ordinance Code Ch. 655) is charged on new development that adds trips and must be paid before the vertical building permit issues; exemptions are listed in Sec. 655.109 and de minimis uses in Sec. 655.108. Ask the Concurrency and Mobility Management System Office (CMMSO@coj.net) whether a single ADU is exempt or de minimis before budgeting, and ask JEA about connection charges if the unit gets its own water or sewer service.. Pre-approved plans: None offered by the city..
| 1-Bedroom Rent | $1,000-$1,350/month |
| 2-Bedroom Rent | $1,350-$1,600/month |
| Annual Rental Income (est.) | $14,100/year |
| Payback Period (est.) | 16.0 years |
| Short-Term Rental | Not addressed in Sec. 656.403(g). Because the lot must keep its homestead exemption, the property has to remain the owner's permanent residence; confirm with the Zoning Section before planning a short-term rental. |
| Overall ROI Estimate | 4-8% annual return (about $12,000-$16,000 a year in rent on a $150,000-$300,000 unit, before taxes, insurance, vacancy and upkeep) |
A typical ADU in Jacksonville generates approximately $14,100 per year in rental income based on average 1-bedroom rents. At an average construction cost of $225,000, the estimated payback period is 16.0 years — before accounting for the resale value the ADU adds, which an appraiser determines from comparable sales in Jacksonville and varies by market (often less than build cost).
1. Garage conversions save 40-60% vs new construction since the shell already exists. Average cost in Jacksonville: $65,000-$130,000.
2. Prefab/modular ADUs offer predictable pricing and faster timelines. Average: $125,000-$200,000.
3. Pre-approved plans — Jacksonville does not offer a pre-approved/standard ADU plan program yet, so budget for custom architectural plans (typically $3,000-$15,000). See which cities offer pre-approved ADU plans.
4. State grants — California's CalHFA ADU grant (up to $40K) is currently paused; check calhfa.ca.gov/adu for status and your state for active programs.
5. Get multiple bids — ADU contractor pricing varies 20-40% for the same project. We recommend getting at least 3 quotes.
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