Minnehaha County, SD Accessory Structures: ADU Rules (2026)

Before April 22, 2025, the 1990 Revised Zoning Ordinance recognized ADUs only narrowly. The MC16-183-25 amendment expanded ADU eligibility countywide in the four residential and ag districts identified above and added Article 12.20 as a stand-alone use regulation. The ordinance defines an ADU as a subordinate dwelling on the same parcel as a larger primary single-family dwelling, providing complete independent living facilities for one family. Three forms are allowed: (a) internal — within the principal dwelling; (b) attached — part of an accessory structure such as a detached garage that shares a wall with another building; or (c) detached — a free-standing structure. Detached ADUs may not exceed 50 percent of the primary dwelling's heated floor area, must observe 7-foot side and rear yard setbacks, and must meet the same front-yard setback as the principal structure. All ADUs are subject to the 2021 IRC adopted by Minnehaha County (Ordinance adopted April 19, 2022), the county on-site wastewater treatment regulations (most unincorporated lots are on septic, not municipal sewer), and a conditional use permit issued by the Minnehaha County Planning Commission after a public hearing. Sioux Falls, Brandon, Hartford, Dell Rapids, and the county's other incorporated cities each regulate ADUs under their own municipal codes — the joint Sioux Falls/Minnehaha zoning ordinance places ADUs under Article 15.20 in the joint-jurisdiction area. South Dakota has NO statewide ADU preemption (contrast California, Colorado, Maine), so the county's conditional-use approach is fully lawful under SDCL Chapter 11-2 county zoning authority.