ADU rules in Bismarck

Since the Land Development Code took effect on October 1, 2026, an ADU in a detached accessory building is a permitted use (P*) in every district that allows single-family homes except Downtown: RRE, RR, RS, RU, RX and A. One ADU is allowed per single-family or two-family dwelling, and the building must stay out of the front setback and meet accessory-building setbacks (5 ft from side and rear lines in RS, RU and RX, reducible to 3 ft with fire-rated walls; 15 ft side and 50 ft rear in RRE and RR). The only lot gate is narrow: on a lot smaller than its district's minimum lot size (4,000 sq ft in RS, 2,000 sq ft in RU and RX) the ADU must be inside the principal building.

A single-family dwelling may contain an ADU within or attached to the house (basement, attic or attached addition), permitted by right in RRE, RR, RS, RU, RX and A under the same use-table entry as detached units. Internal units are also the only option on lots that do not meet the district's minimum lot size. One ADU per single-family or two-family dwelling; the LDC dropped the old one-bedroom cap, so a unit needs at least one bedroom, a kitchen, a bathroom and its own exterior entrance.

For an ADU in an accessory building the floor area may not be greater than 800 sq ft or less than 300 sq ft on any lot of five acres or less, and may be up to 1,200 sq ft on a lot greater than five acres; the measurement covers only the living unit and excludes garage or storage space used by the principal dwelling. An ADU inside the principal structure may not exceed 40 percent of the principal structure's gross floor area, excluding an attached garage and storage or utility areas used by the main home; the old 300 to 800 sq ft window for internal units was dropped. Accessory buildings are capped at 25 ft in height in every ADU district, accessory-building footprint is capped at 1,200 sq ft in RS and RU (4% of lot area in RRE, RR and A), and lot coverage is 40% in RS and RU and 60% in RX.

The Land Development Code contains no owner-occupancy requirement for ADUs or principal dwellings. The repealed Title 14 rule (former §14-03-08(4)(y)(3)(c)) required the owner to occupy the principal or accessory unit as a legal residence for more than six months a year, barred corporate ownership, and ended the special use permit if the owner moved out; the LDC drafting notes record that the rewrite was made more permissive 'such as removing the occupancy requirement and allowing ADUs by-right'. The city's ADU guide (revised 9-3-2026) says 'ADUs may be owner-occupied or rented to a tenant', though one of its bullets still repeats the repealed owner-occupancy termination clause. North Dakota has no ADU statute, so nothing at the state level adds or preempts such a rule.

Table 14-13-1 sets a minimum of 1 parking space per ADU with no maximum, in addition to the single-family minimum of 1 space per dwelling unit. Under the new code required spaces may be met on-street: each 25 uninterrupted linear feet of available on-street parking directly adjacent to the parcel counts as one required space (driveways, no-parking zones and sight triangles excluded). The baseline can also be reduced administratively through a parking adjustment under §14-13-08.

ADUs are a 'P' use, 'permitted by right in the zoning districts in which they are listed', so no special use permit or public hearing is needed; the Building Official reviews the building permit for compliance with the LDC's use-specific standards and issues a certificate of occupancy after final inspection. This replaced the repealed Title 14 process, under which every ADU needed a special use permit from the Planning and Zoning Commission after a published-notice public hearing. Applications filed between adoption (5-26-2026) and the effective date could elect either code; complete applications follow the code in effect at submittal.

The LDC has no occupancy or tenancy limit on ADUs, and the city guide states ADUs 'may be owner-occupied or rented to a tenant'. Short-term rental is a permitted use with standards in every district that allows ADUs (and in RM, RMH, OX, CX, IX and Downtown), and §14-10-04.4.c.ii(5) says 'A short-term rental may be allowed in an accessory dwelling unit', subject to one household at a time, no parties, no exterior signage, residential noise limits and parking available for the full stay. No city STR license or registration appears in Title 5 (Business Regulations) or Title 4, whose Chapter 4-11 rental housing habitability standards exclude transient lodging. The code requires the ADU to be on the same lot as the principal dwelling and says nothing about condominium or separate sale.