ADU rules in Pierre

Pierre's zoning code has no accessory dwelling unit, guest house or second-dwelling use. In every residential district only one building for living purposes is allowed per zoning lot, and since Ord. No. 1880 (2025) the accessory-use section says outright that an accessory structure 'shall not contain features indicative or permissive of a dwelling unit', so a backyard cottage or garage apartment cannot be permitted. Any use not listed in a district is prohibited under Section 12-1-109.

There is no attached ADU use, but in the Two-Family Residential District a two-family dwelling (duplex) is a principal permitted use and an existing house 'may be converted into a Two-Family dwelling' by right, provided any exterior stairway to a second floor is at the rear. In the One-Family A, B, C and D districts only single-family dwellings (or manufactured homes in C and D) are allowed, so a second unit there needs a rezoning. The Multiple Family district allows multiple dwellings outright.

Because Pierre has no ADU category, there is no ADU floor-area limit. A unit created as half of a two-family dwelling in the Two-Family Residential District is governed by that district's space limits: 35 feet or two and one-half stories, a 6,000 square foot minimum lot, 30 percent maximum lot coverage for all buildings, and 25-foot front and rear yards with 6-foot side yards (15 feet combined). Detached accessory structures are one story with the roof peak no higher than the house, and a detached garage may not exceed 1,200 square feet plus 5 percent of lot area beyond the district minimum, but none of these may contain a dwelling unit.

No owner-occupancy requirement applies to the only second-unit route, a two-family dwelling or conversion in the Two-Family Residential District; the district rules impose none. South Dakota has no state ADU statute, so nothing preempts or adds to this. (Property-tax owner-occupied classification under SDCL 10-13-39 is a separate matter, not a zoning rule.)

Two-family dwellings need a minimum of 2.0 off-street parking spaces for each dwelling unit, with one garage space counting as one space; units with one bedroom or efficiency units need 1.0 space each. A single-family house needs two spaces, so converting a house to a duplex generally means adding spaces on the same lot. Parking in one- and two-family districts must have an all-weather surface within one year of the building permit.

Where a second unit is allowed (a two-family dwelling or conversion in the Two-Family Residential District), it is a principal permitted use approved through a building permit from the city inspector with a scaled plot plan; no conditional use hearing applies. Elsewhere it takes a rezoning to the Two-Family or Multiple Family district, or a planned unit housing development (one acre minimum, Planning Commission hearing and City Commission approval) under Article 10.

Nothing in Chapter 12 restricts long-term rental of either unit of a two-family dwelling. Pierre has no vacation-home or short-term-rental chapter in its zoning or licensing codes; hotels, motels, and rooming houses (up to five guest rooms) are separately defined uses, and a home occupation may include room or board for not more than two persons, while a 'tourist home' is expressly not a home occupation. A whole unit rented nightly for more than fourteen days a year is a state-licensed vacation home establishment under SDCL 34-18-1(17).