Asheville, NC Accessory Structures: ADU Rules (2026)

Sec. 7-14-1(b)(3) allows accessory dwelling units as a permitted use across the city's residential zoning districts, except Urban Residential, to allow the efficient use of existing housing stock, parcels of land and community infrastructure. The general provisions in subsection (a) restrict an ADU to a residential lot containing exactly one single-family detached structure, cap the count at one accessory dwelling unit per single-family detached dwelling, and state that an ADU does not count as an additional dwelling unit for calculating minimum lot size or maximum density, meaning adding one does not require subdividing or upzoning the lot.

An ADU can occupy a conforming accessory structure, a lawfully created nonconforming accessory structure, or even a lawfully nonconforming primary structure. Size and height are governed separately by structure type in subsection (b): a detached accessory dwelling unit cannot exceed the lesser of 70 percent of the primary dwelling's gross floor area or 800 square feet, with covered decks, patios, and porches excluded from that floor-area count, and its height is capped at 25 feet. An attached accessory dwelling unit, meaning one sharing a foundation, exterior walls, and roof with the primary home, gets a larger area cap of the lesser of 70 percent of the primary dwelling's gross floor area or 1,000 square feet, and its height follows whatever height limit applies to the residential structure generally rather than a separate ADU-specific number.

Parking is addressed in subsection (c): parking for the primary dwelling must stay in place or be replaced on site, and the ADU itself needs one parking space if off-street parking is otherwise required for the primary unit, located to the side or rear of the primary residence and outside the front setback.