ADU Rules in Indianapolis, Indiana

Indianapolis is the Indiana state capital and the consolidated Indianapolis-Marion County seat ("Unigov"), with a population of about 880,000 — the 16th largest US city. The 1970 Unigov consolidation merged city and county governments, creating the Indianapolis-Marion County Unified Development Code (UDC) for all of Marion County. Indiana has no statewide ADU preemption law — the Indianapolis-Marion County UDC governs.

Indianapolis-Marion County Unified Development Code

The UDC (Chapter 744 of the Revised Code) governs all land use in Indianapolis-Marion County. The city has been expanding ADU allowances in recent years as part of housing affordability efforts.

Permitted ADU Types

Per the Indianapolis-Marion County UDC:

• Accessory dwelling units: Allowed in residential districts (verify current districts)
• Detached ADUs: In rear yards of eligible zones
• Attached ADUs: Additions with separate entrance
• Interior conversions: Converting existing space within primary structure

Indianapolis has been working to simplify ADU approval — verify current standards with the Department of Metropolitan Development.

Size Limits

Per the UDC:

• ADU size limits apply — verify current maximum floor area
• Must be smaller than the primary dwelling in most zones

Setbacks

Per Indianapolis-Marion County residential zone (typical):

• Rear: Minimum setback (varies by zone)
• Side: Minimum setback (varies by zone)
• Detached ADUs: Per accessory structure standards in UDC

Parking

Parking requirements for ADUs in Indianapolis — verify current standards, particularly if near IndyGo transit routes where parking requirements may be reduced.

Fall Creek and White River Floodplains

Parts of Indianapolis near the White River, Fall Creek, and other waterways are in FEMA flood zones. Verify FEMA flood map status before planning in riverside areas.

Historic Districts

Indianapolis has designated historic districts and historic overlay zones including Irvington, Lockerbie Square, and others. Properties in historic overlay zones require additional review.

Permit Process

1. Verify zoning: Indianapolis Department of Metropolitan Development (DMD)
2. Check historic overlay: If applicable
3. Check flood zone: If near waterways
4. Submit plans: Indianapolis-Marion County Building Services
5. Zoning review and building permit
6. Inspections and CO: Required before occupancy

Contact

Indianapolis Department of Metropolitan Development 1200 Madison Avenue, Suite 100, Indianapolis, IN 46225 Phone: (317) 327-3600 Website: indy.gov/activity/metropolitan-development

Disclaimer: Indiana has no statewide ADU law. Indianapolis-Marion County UDC governs locally. ADU policies have been evolving. Verify current standards with the Department of Metropolitan Development before starting any project.