ADU Rules in Indianapolis, Indiana

Indianapolis-Marion County uses the term Secondary Dwelling Unit for what is commonly called an accessory dwelling unit (ADU).

The controlling local standard is Indianapolis-Marion County Code §743-306.GG.

Core Rules

A Secondary Dwelling Unit is subject to the following current standards:

• One per lot per single-family detached dwelling.
• The owner must occupy either the primary dwelling unit or the secondary dwelling unit as the owner's permanent residence.
• Maximum floor area: 720 sq ft.
• One additional off-street parking space is required.
• The secondary unit must have a separate entrance.
• A detached secondary unit must have an entrance visible from a right-of-way.
• A detached unit counts toward accessory-building floor area unless it is above an existing detached accessory building.
• In the Compact Context Area, a detached secondary dwelling unit must be within a permitted accessory building.

Where It Is Allowed

The Indianapolis use table identifies the zoning districts where a Secondary Dwelling Unit is allowed as an accessory use. Do not assume that every Marion County lot is eligible solely because it contains a single-family home.

Use the official zoning browser first:

Indy Zoning Browser

Then check the current use table and §743-306.GG.

Historic and Floodplain Review

Separate historic-preservation, floodplain, and building-code requirements may apply to a specific parcel. These requirements do not replace the zoning rules above.

Official Sources

Indianapolis-Marion County Code — Chapter 743

Indianapolis Department of Metropolitan Development

Disclaimer: Verify the parcel's current zoning and any overlay requirements before preparing permit drawings.