Sioux Falls, SD Accessory Structures: ADU Rules (2026)

Sioux Falls regulates ADUs as an accessory use under Sioux Falls Code § 160.093 (Accessory Uses), within Chapter 160 (Zoning) of the Shape Places ordinance. Only one additional single-family dwelling unit is permitted on a lot already containing a principal single-family dwelling, and at least one of the two units must be owner-occupied. A detached ADU may not exceed 40% of the floor area of the main structure. Additional off-street parking is required as if the ADU were an additional single-family dwelling, governed by §§ 160.550 et seq. (Parking, Loading, and Stacking Regulations). ADUs must comply with the Sioux Falls residential building code (2021 IRC as adopted, Title 50) including snow-load and frost-line requirements typical of South Dakota's cold climate. Because Sioux Falls operates under a home-rule charter (SDCL Chapter 6-12 and SD Constitution Article IX § 2), ADU rules are entirely a product of local zoning policy — there is no statewide ADU preemption in South Dakota (contrast California, Colorado, Maine). Properties on the city fringe may instead fall under the Joint Zoning Ordinance with Minnehaha or Lincoln County (§ 159.305), which uses a 75%/50% sizing rule and requires a conditional use permit.