ADU rules in Deadwood

Deadwood has no detached ADU use: its code defines an accessory dwelling unit as a unit 'within a single-family dwelling unit', and the 'Accessory housing' use listed in R1 and R2 follows that definition. A detached second home is possible only as a second principal building in the R2 multi-family district under 17.60.110, which requires street or alley access, a parking easement and separate utilities for each unit, underground utilities, 10 feet between buildings, and the lot area of both units combined (for example 10,000 sq ft for two single-family homes). In R1 no more than one principal building may stand on a lot unless approved as a planned unit development.

An accessory dwelling unit inside a single-family home (listed as 'Accessory housing') is a use by right in the R2 multi-family residential district but needs a conditional use permit in the R1 residential district, Deadwood's main single-family zone. Duplexes follow the same split (by right in R2, conditional use in R1). Accessory housing is not listed in the A1, PF or commercial districts.

The code sets no floor-area limit for accessory housing; the definition only requires a 'separate and complete single housekeeping unit within a single-family dwelling unit'. R1 and R2 cap principal buildings at 35 feet and accessory buildings at 25 feet. A separately listed 'efficiency living unit' (by right in R2) may not exceed 400 sq ft, but that is its own dwelling type, not an ADU. A second principal building in R2 must meet the R2 area and bulk rules on an aggregate basis.

The definition of an accessory dwelling unit states that 'the single-family dwelling unit shall be owner occupied', an ongoing condition of the use. In R1, where accessory housing needs a conditional use permit, the permit is also temporary, granted to 'a designated person who resides at a residential address', and not transferable to another person or address. The R2 second-principal-building and duplex routes carry no owner-occupancy rule. South Dakota has no state ADU statute that preempts this.

Chapter 17.64 has no ADU entry. Its general table requires two spaces per dwelling unit for one- and two-family dwellings in new construction or new uses in buildings built after 1940, and one space per unit for residential uses inside a mandatory parking district. Uses in buildings built before 1941 in planning unit 4 of the historic overlay zone need no off-street parking. A deferral is available under 17.64.020, and for an R1 conditional use permit the board can attach parking conditions.

In R2, accessory housing is a use by right handled through a building permit. In R1, it needs a conditional use permit: the Planning and Zoning Commission reviews and reports, and the Board of Adjustment holds a published, posted public hearing and decides. R1 and R2 conditional use permits are temporary, personal to a resident, reviewable annually, limited to one per lot, and expire if unused for six months or discontinued for twelve. Projects affecting a building also need Historic Preservation Commission project approval unless staff finds no effect on historic property, and a certificate of appropriateness for any exterior work in planning unit 4.

Chapter 17.53 prohibits transient commercial use of residential property (any single-family dwelling or structure in R1 or R2) for stays under thirty consecutive days. The one exception is fourteen days or less in August, from four days before the Sturgis Motorcycle Rally until three days after it. Vacation home establishments and specialty resorts are 'strictly prohibited' in R1 and R2; a bed and breakfast is possible there only by conditional use permit, at least 200 feet from another, and every short-term rental needs a conditional use permit, a city business license and short-term rental license, a state Department of Health lodging license and state tax certificates. A rented ADU still requires the owner to live in the main home.