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How big a backyard home (accessory dwelling unit) can be in Columbia County, who can build one, and who to call to confirm — from the county's published rules.
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| ADUs allowed? | Yes, with conditions |
|---|---|
| Maximum ADU size | 800 sq ft or 75% of the main home, whichever is less |
| Minimum ADU size | 350 sq ft |
| Owner must live on site? | Not confirmed in our records |
| Manufactured home as an ADU? | Often allowed, subject to the county's ADU and zoning rules |
Columbia County allows one accessory dwelling unit per lot of record under its Land Development Regulations (Sec. 4.2.33). The ADU must be at least 350 sq ft and no larger than 75% of the principal dwelling's habitable floor area or 800 sq ft, whichever is less. It cannot be sold separately from the main home, and its electric service must run through the main home's meter. County seat: Lake City.
Source: Columbia County Land Development Regulations Sec. 4.2.33 (Ord. 2019-07).
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 Columbia County before you build.
Confirm with Columbia County: 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, with conditions. Columbia County allows one accessory dwelling unit per lot of record under its Land Development Regulations (Sec. 4.2.33). The ADU must be at least 350 sq ft and no larger than 75% of the principal dwelling's habitable floor area or 800 sq ft, whichever is less. It cannot be sold separately from the main home, and its electric service must run through the main home's meter. County seat: Lake City.
800 sq ft or 75% of the main home, whichever is less. The minimum ADU size is 350 sq ft.
Our records don't confirm an owner-occupancy requirement for Columbia County — ask the county zoning department before you buy.
Often yes — many Florida counties allow a manufactured or modular home as an accessory dwelling unit, subject to Columbia County's ADU size, lot, and setback rules. Confirm with the county for your parcel.
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