Sioux City, IA Accessory Structures: ADU Permits (2026)

The two-track permitting process for a Sioux City ADU works as follows. Zoning Track: The applicant first verifies that an ADU is permitted in the underlying district under Title 25. If permitted by right, a zoning permit issues from Inspection Services upon a showing of compliance with dimensional standards. If permitted by special exception or conditional use, the application goes to the Sioux City Board of Adjustment (established under Iowa Code §414.7) or the Planning and Zoning Commission for a public hearing with notice required by Iowa Code §414.4. If a variance is needed, the application goes to the Board of Adjustment under §414.12; the Iowa variance standard generally requires unique physical conditions, hardship not self-created, and consistency with the spirit of the ordinance. Building Track: After zoning approval, the applicant submits construction documents to the Building Official under the locally adopted IRC. Plan review confirms structural, electrical, plumbing, mechanical, and energy provisions for one- and two-family dwellings. Inspections occur at footing, foundation, framing, rough-in, insulation, and final stages. A Certificate of Occupancy is issued before the ADU may be occupied. Sioux City typically requires separate utility metering or affidavits for ADUs with kitchens. Properties in the FEMA Special Flood Hazard Area along the Missouri or Floyd Rivers face additional floodplain permit review under Iowa Code §455B.275.