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

Sioux Falls' Shape Places Zoning Ordinance (Title 16) permits ADUs as a subordinate residential use to a principal single-family dwelling under Article 15.20. Both attached ADUs (integrated into the principal dwelling, including basement and above-garage units) and detached ADUs (separate accessory structure on the lot) are allowed in residential zoning districts such as RS (Residential Single-Family), RT (Residential Two-Family), and RM (Residential Multi-Family). Key Article 15.20 standards: (1) the ADU must be clearly subordinate in size to the principal dwelling, typically not exceeding a defined percentage of the primary dwelling's gross floor area; (2) the property must retain the appearance of a single-family residence from the street; (3) the ADU cannot be sold separately from the principal dwelling (no separate platting or condominium conversion); (4) the lot must meet minimum size and setback requirements for the zoning district; (5) off-street parking sufficient for both units is required under Article 15.04 parking standards. Building permits are issued by Planning and Development Services and trigger plan review under Sioux Falls Code Chapter 150 Building Regulations, which adopts the 2018 International Residential Code (IRC) and 2018 International Building Code (IBC) consistent with SDCL Chapter 11-10 statewide building code mandates. Floodplain review under Code Chapter 154 applies if the lot intersects the Big Sioux River, Skunk Creek, or other mapped FEMA Special Flood Hazard Areas. Frost-depth foundations to approximately 42 inches below grade are required for South Dakota's freeze-thaw climate. South Dakota does not have a statewide ADU preemption statute analogous to California SB 9 or Oregon HB 2001 — Sioux Falls' rules govern.