Hendersonville, TN Accessory Structures: ADU Rules (2026)

Hendersonville's accessory-dwelling framework is one of the more restrictive in Middle Tennessee, codified in Zoning Ordinance Chapter 10.4 and detailed in the city's Accessory Dwellings Information Packet (updated 6/22/2022). Tennessee state law does NOT preempt local ADU rules — there is no statewide ADU-allow statute like Colorado HB24-1152 — so Hendersonville's rules apply in full. General conditions (apply to both attached and detached): owner must reside FULL-TIME on the property (≥75% of the calendar year); occupants must be parents, grandparents, great-grandparents, children, stepchildren, in-laws, nieces/nephews, or domestic employees and their families; one driveway; at least 4 off-street parking spaces (garage/carport not counted); one utility meter per utility type; one mailbox/address; recorded COVENANT with Sumner County Register of Deeds; zoning permits before construction; utility-capacity verification; only one attached apartment OR one detached dwelling per lot. ATTACHED Accessory Apartment standards: heated area ≤ 40% of total heated area (dwelling + apartment combined); accessible from interior of the house via door or stairs (NOT via breezeway or enclosed hallway); attachment must be by common wall or roofline (a room at least 7' x 10'); one front door per street frontage; not permitted if restrictive covenants prohibit; NO variance available. DETACHED Accessory Dwelling standards: lot must be at least 30,000 square feet; located in the rear yard behind the rear plane of the principal dwelling; at least 20 feet from side and rear property lines (may be above a detached garage or connected via breezeway/hallway); design must be architecturally consistent with the principal dwelling; front door (if visible from street) must appear clearly secondary; CONDITIONAL USE PERMIT from the Board of Zoning Appeals is REQUIRED ($250 nonrefundable fee); not permitted if restrictive covenants prohibit; periodic inspections allowed. Size caps tied to lot size (whichever is less of 50% of principal dwelling OR): lots <15,000 sq ft — detached NOT allowed; 15,001-30,000 sq ft — detached NOT allowed; 30,001-43,559 sq ft — detached allowed via CUP, max 1,200 sq ft (no variance); 1-3 acres — max 1,500 sq ft (no variance); 3+ acres — max 1,800 sq ft (no variance). Height: not to exceed the existing house or 35 feet, whichever is less; for single-story houses, 1.5× the existing house height.