Wilmington, NC Accessory Structures: ADU Rules (2026)

Attached accessory apartments, Sec. 18-247, are permitted in the R-7, R-10, R-15, R-20 and PD Districts if the unit adds two off-street parking spaces, has a separate entrance screened from the public right-of-way, makes no exterior change to the principal structure visible from the right-of-way, and is submitted on a site plan approved by the city manager. Size is capped at a minimum of 200 square feet and a maximum of the lesser of 35 percent of the principal structure's gross floor area or 800 square feet.

Detached accessory apartments, Sec. 18-248, reach further into the R-5, R-3, MF-L, MF-M, MF-MH, MF-H, HD, HD-R and HD-MU Districts, but the host lot must exceed the district's minimum lot area by the lesser of 50 percent or 5,000 square feet, and the detached unit is capped at the lesser of 35 percent of the principal dwelling's heated square footage or 1,200 square feet (800 square feet if built over an existing detached garage). Detached units need two additional parking spaces, must sit entirely behind the rear facade plane of the principal structure, and follow Sec.

18-249's accessory building rules except for a relaxed side and rear setback of 15 feet or the district's principal-structure setback, whichever is less, never below 5 feet. Only one accessory apartment, attached or detached, is allowed per lot under both sections, and in the MF-L, MF-M and MF-H multifamily districts an accessory apartment is permitted only alongside a single-family detached development within that district.