Sioux City, IA Accessory Structures: ADU Rules (2026)
ADU rules in Sioux City, IA, also called accessory dwelling unit regulations or granny flat ordinances, cover setbacks, owner-occupancy, parking, and permit requirements.
Key Facts
- ADU types allowed
- Integrated Unit; Two-Story ADU
- Minimum lot size
- 7,000 square feet
- Accessory to
- Single-family detached homes only
- Per-lot limit
- One ADU maximum
- Section
- § 25.02.260
Summary
Sioux City allows two types of accessory dwelling units, but only on single-family lots of at least 7,000 square feet in listed zoning districts, per Municipal Code § 25.02.260.
Accessory dwelling units (ADUs) are permitted only according to the standards of this Section. 2. Accessory Dwelling Unit Types. For the purposes of this Code, there are two types of ADUs permitted in the City (See Figure 25.02.260, Illustrative ADU Types):
a. Integrated Units are those units that are created within or attached to an existing principal building such that they appear to be a fully integrated part of the building; and
b. Two-Story ADU Buildings are one-and-one-half story or two-story buildings that contain an accessory dwelling unit, which is usually located above a detached garage.
Figure 25.02.260 Illustrative ADU Types Integrated Basement ADU
Integrated ADU https://online.encodeplus.com/regs/siouxcity-ia/doc-viewer.aspx#secid-963
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8/12/26, 3:47 PM
Document Viewer | Municipal Code Figure 25.02.260 Illustrative ADU Types
Detached ADU
Detached Two Story ADU
3. Permitted Locations. Accessory dwelling units are allowed as set out in Table 25.02.260, Districts and ADU Types. Accessory dwelling units are: a. Not allowed in districts that are not listed in this table. b. Not allowed on lots that are less than 7,000 square feet. c. Only allowed as an accessory to single-family detached principal buildings.
4. Conversion of Garages. Garages shall not be converted into accessory dwelling units, unless: a. If a one car garage is converted, at least one replacement parking space is provided elsewhere on the lot; or
Full Breakdown
The zoning code recognizes two ADU forms: Integrated Units built within or attached to the main house so they look like part of it, and Two-Story ADU Buildings, typically located above a detached garage. ADUs are allowed only in the districts and sub-districts listed in Table 25.02.260 (which spans Agriculture, Suburban/Urban/General Residential, Mixed Use, and the Neighborhood Conservation sub-districts), only on lots of 7,000 square feet or more, and only as an accessory to a single-family detached principal building -- with no more than one ADU per lot.
Violations & Fines
An ADU built in an unlisted district, on a lot under 7,000 square feet, as more than one per lot, or as an accessory to anything but a single-family detached home violates § 25.02.260 and is subject to zoning enforcement.
Frequently Asked Questions
What types of accessory dwelling units does Sioux City allow?
Is there a minimum lot size for an ADU in Sioux City?
Sources & Official References
Other rules in Sioux City
How Sioux City compares: Easiest Cities to Build an ADU·Compare Sioux City to another location·View the Iowa accessory structures overview
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