5 county-level rules, plus city-specific rules for 1 city in Hamilton County, Tennessee.
Verified from official government sources
In Chattanooga (Hamilton County's seat), one accessory dwelling unit is allowed per single-unit detached lot, capped at 800 square feet, on a permanent foundation and same owner. Detached ADUs go in the rear or interior side yard only.
Chattanooga City Code § 38-43(b)
Only one ADU is permitted per lot per single-unit detached dwelling... The maximum size of a detached ADU cannot exceed a gross square footage of 800 square feet... Shipping containers and recreational vehicles are prohibited as an ADU.
In Chattanooga, a detached shed or accessory structure must sit at least five feet from interior side and rear lot lines, stay out of front and corner side yards, top out at 24 feet, and never exceed the height or footprint of the main house.
Chattanooga City Code § 38-50
Detached accessory structures must be setback as follows... A minimum of five feet from any interior side or rear lot line... The maximum height of any detached accessory structure is 24 feet... however, no accessory structure may exceed the height of the principal building.
Chattanooga zoning lets an existing detached garage be legally converted into an accessory dwelling unit. Once approved as an ADU, it may add cooking facilities and must meet the 800-square-foot ADU standards; otherwise garages cannot contain kitchens above parking.
Chattanooga City Code § 38-45 (Detached ADU definition)
This can include an existing garage or other accessory structure detached from the principal dwelling unit that is legally converted (fully or partially) to an accessory dwelling unit.
A detached carport in Chattanooga may not sit closer than five feet to any lot line, is banned from required front and corner side setbacks, and cannot exceed 24 feet wide, 22 feet long, and 15 feet high.
Chattanooga City Code § 38-51(c)
A carport may not be erected closer than five feet from any lot line... No carport is permitted in a required front setback or corner side setback... A carport cannot exceed 24 feet in width, 22 feet in length, and 15 feet in height.
Chattanooga has no separate tiny-home ordinance; a backyard tiny house is regulated as an accessory dwelling unit. It must sit on a permanent foundation, stay under 800 square feet, and cannot be a shipping container or recreational vehicle.
Chattanooga City Code § 38-43(b)(15)
Shipping containers and recreational vehicles are prohibited as an ADU... The ADU must have a permanent foundation either through digging and pouring a footer or being attached to an existing permanent structure.
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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