ADU rules in Brookings

Brookings's zoning code has no accessory dwelling use, and a backyard cottage has no route on a residential lot. The definition of accessory building says it "does not include dwelling units or living quarters," Sec. 94-365(a) limits accessory buildings in every residential district to garages, sheds, gazebos, greenhouses, pet shelters, pools and courts and similar incidental uses, and Sec. 94-392 (as amended by Ord. No. 25-002, 2-11-2025) allows more than one main building on a lot only where the lot is used for a business, commercial, civic or industrial purpose. A second detached house therefore needs its own lot meeting the district's full lot standards.

There is no attached or internal ADU use, but a second unit inside or attached to a house is possible as a two-family dwelling (a building "designed or used exclusively for occupancy by two families"). Two-family dwellings are permitted by right in the R-2, R-3, R-3A and RMH districts and need a conditional use permit in the single-family R-1B, R-1C and R-1D districts, where Sec. 94-304 also requires one frontage on an arterial or collector street. They are not allowed at all in the R-1 rural estate or R-1A districts. The lot must meet the two-family minimums (for example 9,900 sq ft and 65 ft wide in R-2).

Because Brookings has no ADU use, no unit-size cap applies; a second unit is a full dwelling unit in a two-family building governed by the district's density, lot-area, yard and 35 ft height rules. The per-unit density in R-2 is 4,950 sq ft (9,900 sq ft lot, 65 ft width); in R-1B 6,200 per unit (12,400 sq ft lot, 90 ft width); in R-1C 5,625 per unit (11,250 sq ft lot, 75 ft width); and in R-1D 4,500 per unit (9,000 sq ft lot, 75 ft width). Sec. 94-365(a)(6) caps all accessory buildings on a residential lot at 25 percent of the rear yard or 1,000 sq ft, whichever is less (more on lots of one acre or larger), but those buildings cannot contain a dwelling unit.

No section of Chapter 94 or the rental-dwelling article requires an owner to live in either unit of a two-family dwelling, and the conditional use standard for two-family dwellings (Sec. 94-304) adds only the street-frontage rule. The only owner-presence rules in the zoning code apply to bed and breakfast establishments, whose meals "shall be prepared in the owner's kitchen." South Dakota has no statewide owner-occupancy rule either way. The city council may attach conditions when it grants a conditional use permit in R-1B, R-1C or R-1D.

Sec. 94-433(c)(1) requires two spaces for each single-family dwelling unit and, for a two-family dwelling, one space for each bedroom, with each garage stall counted as one space. Converting a house to two units is a change in occupancy type that triggers the requirement for sufficient off-street parking under Sec. 94-433(a). Only the B-1 Central Business District is exempt from off-street parking.

Where a two-family dwelling is a permitted use (R-2, R-3, R-3A, RMH), the route is administrative: a zoning and use registration permit from the community development director under Sec. 94-50 plus a building permit. In R-1B, R-1C and R-1D it is a conditional use, which requires a published and posted public hearing before the planning commission and then a city council hearing and decision (Secs. 94-221 to 94-227). In R-1 and R-1A no second unit is possible without rezoning.

Sec. 22-401 makes it unlawful to rent any dwelling unit without first obtaining a dwelling unit rental license, and the city's Building Services staff inspect and license rental units for up to four years. Sec. 22-374 limits each dwelling unit to one family, defined to allow no more than three adults unrelated by blood or law, which matters in this college town. Chapter 94 does not define or regulate short-term or vacation rentals; a dwelling is defined as being for permanent habitation and excludes structures used primarily for transient residents, and the bed and breakfast use (conditional in R-1B, R-1C, R-2 and the R-3 districts) is limited to a single-family dwelling, two guestrooms and stays of no more than 14 days in any 120-day period. Whole-unit nightly rental would also need a state vacation home establishment license (SDCL 34-18-1(17)); confirm with the city before short-term renting.