ADU rules in Williston

Williston's zoning ordinance (Ordinance 613, codified as Chapter Z) has no accessory dwelling unit use, and two provisions block a backyard unit. Section 25.B says no accessory building 'shall be used for dwelling purposes other than by domestic servants employed entirely on the premises', and Section 25.C allows, in any district, 'no more than one structure housing a permitted or permissible use' on a lot. City staff told the Planning and Zoning Commission on March 16, 2026 that 'the current zoning ordinance does not permit accessory dwelling units', and the commission voted 7-0 on May 18, 2026 to deny proposed Ordinance 1167, which would have allowed attached, detached and internal ADUs by special permitted use. The live-in domestic employee allowance is not an ADU: no family member or tenant may live there.

There is no attached or internal ADU either, but a second unit inside or attached to a house is lawful in some districts as a two-family dwelling. Section 31 defines a two-family dwelling to include 'a building containing two single-family dwelling units located on the same lot', and a duplex as two units 'separated horizontally or vertically, within a single building on a single lot'. So a basement apartment or addition with its own kitchen makes the house a duplex. Duplexes or two-family dwellings are permitted by right in R-2 (lot of at least 8,000 sq ft, 50 ft wide), R-3 (6,000 sq ft, 50 ft), and the manufactured-home districts R-6 and R-7 (8,000 sq ft, 60 ft). In R-1 a two-family dwelling is only a special permitted use, and A, R-1E, R-1A and R-4 have no two-family route at all.

With no ADU use there is no ADU square-foot or percent-of-house cap; on the two-family route both units are full dwellings, and the code sets floors rather than caps: R-1, R-2 and R-3 require a minimum floor area of 800 sq ft for any dwelling (R-3: 'Single-family and two-family. The minimum floor area shall be 800 square feet, excluding garage'), without saying whether that applies per unit or per building. Height is capped at 35 ft (45 ft in R-3), and building coverage at 35 percent of the lot in R-1 and R-2. Detached accessory buildings are limited by Section 25.B.9: on lots under 24,000 sq ft, at most two buildings totaling 1,200 sq ft, and on larger lots 5 percent of the lot with at most three buildings, none larger than the house, and none may be lived in except by domestic employees. The denied Ordinance 1167 would have capped ADUs at 800 sq ft and 80 percent of the house; it is not law.

There is no ADU for an owner-occupancy rule to attach to, and the one lawful way to add a unit, a two-family dwelling or duplex, carries no residency condition in any district list (R-2 simply permits 'Single-family detached, twinhomes, and duplexes'). The only owner-occupancy language in the whole zoning ordinance is the bed and breakfast inn definition. The denied Ordinance 1167 would have required the owner to live in the main house at least six months a year, but the commission rejected it on May 18, 2026. North Dakota has no statute that imposes or preempts ADU owner occupancy.

Each residential district section says 'Two spaces per dwelling', and the Section 25.H table requires 2.00 spaces per unit for single-family dwellings. Converting a house into a duplex therefore raises the requirement from 2 to 4 paved spaces. Section 25.H.1 also applies the parking rules when a building is enlarged by more than 1,000 sq ft or 10 percent of its footprint. Ordinance 1182 (adopted September 8, 2026, not yet codified) raised multifamily parking to 2.00 per unit and left the single-family ratio unchanged. The denied Ordinance 1167 would have required one extra space per ADU.

There is no ADU permit, so the process depends on the two-family route and the district. In R-2, R-3, R-6 and R-7 a duplex is a permitted use: the Building Official issues a building permit and a certificate of occupancy (Sections 26.D and 26.E), with no hearing. In R-1 a two-family dwelling is a special permitted use, which means a written application ($250 fee) and a hearing before the Planning and Zoning Commission, which may deny it or attach conditions (Section 27). In A, R-1E, R-1A and R-4 the only route is a rezoning. A detached second dwelling cannot be approved anywhere, because Section 25.B bars living in accessory buildings and the Board of Adjustments may not grant a variance 'to allow a use not permissible' in the district (Section 28.B.2.c).

The code has no rental license, rental registry or landlord program: full-code searches for rental unit, rental housing, rental property, landlord and short-term rental found nothing, so a two-family unit created lawfully may be rented long term, subject to the 'family' limit of no more than four unrelated persons per unit. Short-term lodging in a home appears only as a 'Bed and breakfast inn', defined as 'an owner-occupied house, or portion thereof, where short-term lodging rooms ... are provided for compensation' with at most seven guest rooms, and it is a special permitted use in R-1E, R-1A, R-1, R-2 and R-3. Staff told the commission on March 16, 2026 that current zoning does not permit short-term rentals under 30 days, but the code contains no such definition; the city lodging tax (Section 9-125) reaches hotel, motel and tourist court stays under 30 days. Accessory buildings cannot be rented as dwellings at all (Section 25.B).