Accessory Structures in Hamilton County, TN (2026)
5 county-level rules, plus city-specific rules for 1 city in Hamilton County, Tennessee.
Verified from official government sources
ADU Rules
Hamilton County allows one accessory dwelling unit per single-family lot in unincorporated areas under Resolution No. 924-23, adopted September 18, 2024. A detached ADU tops out at 24 feet and 800 square feet; an attached ADU matches the principal structure's height limit. ADUs are barred in the A-1 Agricultural District and require a lot on public sanitary sewer, not a septic tank.
Hamilton County ADU Zoning and Size Rules
Some RestrictionsHamilton County Resolution No. 924-23 (Sept. 18, 2024), Zoning Regulations Art. V § 306
306 - Height and Area Regulations 1) Height: (a) Detached ADU: Twenty-four (24) feet or two (2) stories maximum and cannot exceed height of the principal dwelling unit if it is lower than twenty-four feet. (b) Attached ADU: Must meet the maximum height of the zone district and cannot exceed the height of the principal dwelling unit. ... 4) Size/Massing: a) Detached: The maximum size of an ADU s...
ADU Owner Occupancy
Hamilton County requires the property owner to live on site before adding an accessory dwelling unit. Section 304 of Resolution No. 924-23 ties ADU ownership to the principal home and requires the owner to occupy one of the two units as a permanent residence, closing off pure rental-investment ADUs in unincorporated areas.
Hamilton County ADU Owner-Occupancy Rule
Some RestrictionsHamilton County Resolution No. 924-23 (Sept. 18, 2024), Zoning Regulations Art. V § 304
304 - Ownership 1) The ADU shall be owned by the same property owner(s) as the principal dwelling unit and cannot be subdivided or otherwise separated in ownership such that the ADU is located on a different lot than the principal dwelling unit. Under no circumstances shall the ADU be converted to a horizontal ownership regime or a fee simple condo. 2) The property owner(s) must occupy one of t...
ADU Rental Restrictions
Hamilton County flatly prohibits renting an accessory dwelling unit as a short-term vacation rental. Section 305 of Resolution No. 924-23 bars both detached and attached ADUs from STVR use, closing off the most common workaround for turning a new accessory unit into an investment listing rather than housing.
Hamilton County Bars ADU Short-Term Rentals
Significant RestrictionsHamilton County Resolution No. 924-23 (Sept. 18, 2024), Zoning Regulations Art. V § 305
305 - Short Term Vacation Rentals 1) The detached or attached ADU cannot be used or rented for the use of a Short-Term Vacation Rental.
Shed & Carport Rules
In unincorporated Hamilton County, a detached shed or accessory building cannot cover more than a third of the rear yard and must stay at least five feet off the side and rear lot lines. Zoning Regulations Section 103.E gives small 12-by-12-foot storage buildings looser eave-height and setback rules, but anything larger, or built after the house, needs its own permit from the Building Commissioner.
Hamilton County Accessory Building Setbacks
Some RestrictionsHamilton County Zoning Regulations, Art. VI, § 103.E (Location of Accessory Buildings on a Lot)
E. Location of Accessory Buildings on a Lot (1) A detached accessory building shall not occupy more than 1/3 of the area of a rear yard. ... (5) No detached accessory building shall be erected, altered or moved so as to be within five feet of the side line of the front half of an adjacent lot. ... (8) Small storage buildings, not larger than twelve feet by twelve feet (12' x 12') and with a max...
Garage Conversions
Hamilton County lets homeowners legally convert an existing garage into an accessory dwelling unit under Resolution No. 924-23. Section 308 defines both attached and detached ADUs to include converted garage space, but the resulting unit must still meet the same 800-square-foot cap, permanent-foundation, and separate-entrance standards as new construction.
Hamilton County Garage-to-ADU Conversion Rules
Some RestrictionsHamilton County Resolution No. 924-23 (Sept. 18, 2024), Zoning Regulations Art. V § 308
308 - Definitions 1) Attached Accessory Dwelling Unit: An additional subordinate dwelling unit located on the same lot as a principal dwelling unit which is joined to another dwelling at one (1) or more sides by a wall and contained entirely within the footprint of the principal dwelling unit. Examples include converted living space, attached garages, basements or attics; additions; or a combin...
Accessory Structures by City in Hamilton County
1 cities in Hamilton County have their own accessory structures rules. Each link goes to that city's dedicated page with code citations.
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