Home › ADU Rules by County › Duval County
How big a backyard home (accessory dwelling unit) can be in Duval County, who can build one, and who to call to confirm — from the county's published rules.
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| ADUs allowed? | Yes |
|---|---|
| Maximum ADU size | 750 sq ft or 25% of the main home, whichever is less |
| Owner must live on site? | Yes — in the main home or the ADU |
| Manufactured home as an ADU? | Often allowed, subject to the county's ADU and zoning rules |
Jacksonville (consolidated with Duval) allows ADUs in most low-density single-family zones (Ord. 2022-0448-E). Owner must live in the primary home OR the ADU — not rent out both. ADU cannot be taller than the primary home. not permitted under city rules in the Beaches (Atlantic Beach, Neptune Beach, Jacksonville Beach) or Baldwin, which self-govern.
Source: City of Jacksonville Zoning Code Sec. 656.403; verified Jul 2026.
Before You Build
ADU rules are set by each county and city — Florida law (Fla. Stat. 163.31771) lets local governments allow ADUs but doesn't require it — and they can change, so always confirm the current rule with Duval County before you build.
Confirm with Duval County: 904-255-7800 · zoning department website ↗
Zoning is set locally and changes often. Answers are guidance only, not a permit guarantee. Always confirm with the local building/zoning department before purchase.
Common Questions
Yes. Jacksonville (consolidated with Duval) allows ADUs in most low-density single-family zones (Ord. 2022-0448-E). Owner must live in the primary home OR the ADU — not rent out both. ADU cannot be taller than the primary home. not permitted under city rules in the Beaches (Atlantic Beach, Neptune Beach, Jacksonville Beach) or Baldwin, which self-govern.
750 sq ft or 25% of the main home, whichever is less.
Yes. Duval County requires the owner to live on the property, in either the main home or the ADU.
Often yes — many Florida counties allow a manufactured or modular home as an accessory dwelling unit, subject to Duval County's ADU size, lot, and setback rules. Confirm with the county for your parcel.
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