ADU rules in Aberdeen

Aberdeen's zoning code (City Code Chapter 60) has no accessory dwelling unit use: quoted Municode searches for 'accessory dwelling', 'accessory dwellings', 'accessory apartment', 'guest house', 'garage apartment' and 'second dwelling' return zero hits. A backyard cottage or garage apartment with its own living facilities would be a second dwelling unit, and Sec. 60-115 allows 'Only one principal building and its customary accessory buildings' on any lot. Accessory buildings must be 'customary and clearly incidental' and serve 'exclusively the principal building or principal use' (Sec. 60-1), and the residential district lists name garages, sheds and playhouses, never living quarters. The only multi-building exception is a BZA-approved group project on a site of at least two acres (Sec. 60-155), which is not a backyard ADU route.

There is no attached or internal ADU either, but a second unit inside or attached to a house is lawful as a two-family dwelling where the district allows one. A single-family dwelling is 'a building having one dwelling unit' (Sec. 60-1), so a basement or addition with complete living facilities turns the house into a two-family dwelling. Two-family dwellings are a permitted use in R-2 (Sec. 60-54(b)(3)) and, by reference, R-3 (Sec. 60-55(b)), and in the M-AG mini-agricultural district (Sec. 60-64(b)(2)); in R-1 they need a Board of Zoning Adjustment special exception after a public hearing (Sec. 60-53(c)(3)). The lot must meet the two-family minimums in Sec. 60-91: 17,000 sq ft in R-1, 10,000 sq ft in R-2 and 4,000 sq ft in R-3.

Chapter 60 sets no size for an accessory dwelling because none exists, and it sets no floor-area cap for either unit of a two-family dwelling; the controls are the Sec. 60-91 table (minimum lot area, width, setbacks, density in families per net acre, and height of 35 ft in R-1 and 45 ft in R-2 and R-3). For scale, the residential district sections cap an accessory building's footprint at the principal building's footprint and 15 percent of the lot, require it to sit in the rear yard with an exterior compatible with the house, and send any structure with side walls higher than ten feet to the Board of Zoning Adjustment as a special exception (Secs. 60-53(b)(8), 60-54(b)(1), 60-55(b)). Those buildings may not be dwellings.

No ADU exists for an owner-occupancy rule to attach to, and the one lawful way to add a unit, a two-family dwelling, is listed in R-2, R-3 and M-AG as a permitted use with no residency condition. Quoted Municode searches for 'owner occupied' and 'owner-occupied' return zero hits in the whole City Code. South Dakota has no state ADU owner-occupancy rule either way.

Ord. 26-09-03, adopted 9-28-2026, published in the city's official newspaper (the Aberdeen Insider) on 10-1-2026 and effective 10-21-2026 with no referendum invoked, rewrote the Sec. 60-159 table to require 'Two spaces for each home or dwelling unit' for 'Single-family residential dwellings' and 'One and one-half spaces for each dwelling unit' for 'Multifamily residential dwellings' (one space per unit in the Aberdeen Commercial Historic District). It struck the old catch-all row, 'Residential dwellings, including single-family, multifamily, apartments, condominiums, townhouses and high-rises', which had required 1.5 spaces per unit for every dwelling type. Multifamily means a residence of 'three or more families' (Sec. 60-1), and the amended table has no two-family row and no rule for unlisted uses, so whether a duplex conversion needs 1.5 or 2 spaces per unit is a staff interpretation; ask the Community Development office before designing the site. Each space must now be at least 9 by 18 feet with access to a street or alley, and the planning and zoning director may grant an administrative exception for 'Parking, loading and unloading spaces' (Sec. 60-197(b)(2)d). Municode and the city's compiled code PDF still print the superseded table.

It depends on the district. In R-2, R-3 and M-AG a two-family dwelling is a permitted use, so a conversion needs the zoning permit the zoning inspector must issue when the plans conform (Secs. 60-218, 60-219, within ten days) plus a building permit. In R-1 a two-family dwelling is a special exception the Board of Zoning Adjustment decides 'in its discretion' after a public hearing on the Sec. 60-193 criteria. In A-1 and the other districts there is no route short of a rezoning, and Sec. 60-198(d)(2) bars a variance that 'will permit a use of land, building, or structure which is not permitted in the district'.

Quoted Municode searches for 'short-term rentals', 'vacation homes', 'vacation rental', 'rental license', 'rental registration', 'owner occupied' and 'tourist home' return zero hits ('short-term' finds only a kennel permit and the health care district), so the City Code has neither a short-term rental regime nor a long-term rental licensing program. Zoning defines a hotel as lodging 'open to transient guests' and lists boardinghouses in R-2 only when 'not intended as tourist accommodations' (Secs. 60-1, 60-54(b)(2)); it never addresses a whole dwelling rented by the night, so expect a zoning question for that use. Chapter 50 levies a $2.00 per night occupational tax on transient guests of listed lodging establishments in Business Improvement District No. 2 (bed and breakfasts and hotels under 25 rooms excluded). State law licenses a 'vacation home establishment' rented in its entirety on a daily or weekly basis for more than fourteen days a year (SDCL 34-18-1(17)), through the Department of Health.