Chapel Hill, NC Accessory Structures: ADU Rules (2026)

Chapel Hill's Land Use Management Ordinance authorizes a 'Single-Family Dwelling Unit with Accessory Apartment' under Sec. 6.19.1, covering both attached apartments built into or added onto the main house and detached accessory apartments sited on the same zoning lot or on a sublot. The base floor area limit is 1,000 square feet, but the Planning Director may grant an exception to that cap when three conditions are all met: the apartment is within an existing structure and does not increase that structure's footprint, whether the structure is the principal dwelling, a garage, or another existing standalone building; the apartment is contained on a single floor except for necessary access points; and the apartment's floor area does not exceed one-third of the primary dwelling unit's floor area.

Height is separately capped: a detached accessory structure in an R-zoning district cannot exceed 29 feet, or the height of the primary structure, whichever is less, so a homeowner cannot build a taller garage apartment than the house it accompanies. The ordinance limits each single-family zoning lot to one accessory apartment, meaning a property cannot add both an attached apartment and a separate detached unit. Because Chapel Hill treats the accessory apartment as part of a broader 'Two-Family Dwelling Unit' framework in Article 6, homeowners pursuing an ADU should also check the shared driveway, utilities, and tree-canopy standards in Sec.

6.19.4 that apply to the underlying lot. A zoning compliance permit from the Town Manager's office, issued under LUMO Sec. 8.6, is required before construction begins, and town staff can inspect the property to confirm the finished apartment matches the approved plans.