ADU Rules in Marshalltown, Iowa

Marshalltown is the Marshall County seat with a population of about 27,000 in central Iowa. On July 19, 2018, an EF3 tornado struck the city directly, causing widespread damage to the historic downtown, the courthouse, and many residences. The city has been in an ongoing rebuilding process. Iowa has no statewide ADU preemption law — Marshalltown's local zoning governs.

Marshalltown Zoning Code

The City of Marshalltown Zoning Ordinance governs all land use. The city has been updating and rebuilding since the 2018 tornado.

Permitted ADU Types

Depending on the residential zone:

• Accessory apartments: Conversion within primary structure
• Detached accessory dwelling units: In rear yards of eligible zones

Verify current ADU provisions with Marshalltown's Planning Division.

Size Limits

Accessory dwelling units are subject to:

• Maximum floor area per zone
• Lot coverage restrictions

Verify current limits with Marshalltown Planning.

Setbacks

Per Marshalltown residential zone (typical):

• Rear: Minimum setback
• Side: Minimum setback
• Accessory structures: Per ordinance

Post-Tornado Rebuilding Context

Properties damaged in the 2018 tornado may be in various stages of repair or rebuilding. If you are working on a tornado-damaged property:

• Verify current property status and any outstanding permits or orders
• Check whether the property is in a tornado recovery program
• Contact Marshalltown's Building Division for guidance on rebuilding

Iowa River Considerations

Parts of Marshalltown near the Iowa River may be in FEMA flood zones. Verify flood map status.

Permit Process

1. Verify property status: Especially for tornado-affected properties
2. Verify zoning: Marshalltown Planning Division
3. Check flood zone status: If near the Iowa River
4. Submit plans: Marshalltown Building Division
5. Building permit and inspections
6. CO: Required before occupancy

Contact

City of Marshalltown Planning Division 11 North Center Street, Marshalltown, IA 50158 Phone: (641) 754-5725 Website: ci.marshalltown.ia.us

Disclaimer: Iowa has no statewide ADU law. Marshalltown zoning governs locally. Verify current ADU allowances and any tornado recovery considerations with the City of Marshalltown before starting any project.