ADU Rules in Indianapolis, IN (2026)
ADU rules, permit requirements, size limits, and fees for Indianapolis, IN. Source-cited from official municipal code.
Yes, ADUs are allowed in Indianapolis, IN.
Indianapolis, IN permits accessory dwelling units (ADUs) on residential properties. ADUs — also called granny flats, in-law units, backyard cottages, or secondary suites — are secondary housing units on a single-family or multifamily lot. State and local law governs the approval process. In Indianapolis, the Indianapolis Department of Metropolitan Development (DMD) — Building Permits handles ADU permit applications. Below you will find the current size limits, setbacks, fees, and timeline for building an ADU in Indianapolis.
ADU Size Limits
ADU Size Limits in Indianapolis: Detached ADU: up to 900 sq ft (max height: 22 feet). Attached ADU: Up to 35% of primary dwelling floor area. Indianapolis-Marion County Unified Development Ordinance (UDO). Accessory dwelling units (also called 'carriage houses' or 'garage apartments' in Indianapolis context) limited to 900 sqft for detached units. Attached/internal conversions up to 35% of primary floor area. Indianapolis does not use the California JADU terminology.
| Type | Max Size | Max Height |
|---|---|---|
| Detached ADU | 900 sq ft | 22 feet |
| Attached ADU | Up to 35% of primary dwelling floor area | Per zone height limit |
Permit Fees
ADU Permit Fees in Indianapolis: Plan check fee: $150–$700. Building permit fee: $400–$2,500 based on construction value. Impact fees: None. School fees: None or N/A. Total estimated permit cost: $700–$4,000 total fees. Indianapolis-Marion County does not impose development impact fees. Citizen Energy (gas) and AES Indiana (electric) connection fees apply for new ADU utility connections. No separate school impact fees. Indianapolis's low fee structure makes it relatively affordable for ADU development compared to western cities.
| Fee Type | Amount |
|---|---|
| Plan Check | $150–$700 |
| Building Permit | $400–$2,500 based on construction value |
| Impact Fees | None |
| School Fees | None |
| Total Estimate | $700–$4,000 total fees |
Permit Timeline
Indianapolis ADU Permit Timeline: Indianapolis-Marion County Department of Metropolitan Development (DMD) processes permits. Typical timeline: 3-6 weeks for zoning certification, 2-4 weeks for building permit. Indianapolis Access (indygo.indy.gov portal) available for online applications. Simple ADU/garage apartment projects may qualify for expedited review. Apply through the Indianapolis Department of Metropolitan Development (DMD) — Building Permits online permit portal. Phone: (317) 327-5136.
Setback Requirements
ADU Setback Requirements in Indianapolis: Front setback: follows zone standard. Side setback: 3 feet. Rear setback: 5 feet. Indianapolis-Marion County UDO. Detached ADUs require 5 ft rear setback and 3 ft side setback. Indianapolis has extensive alley network in the Old Northside, Fountain Square, Irvington, and other historic neighborhoods — rear-loaded lots allow alley-access ADU placement. Corner lots have additional street-facing setback requirements.
Parking Requirements
Parking Requirements: 1 space per ADU required. Parking may be provided in driveway, garage, or off-street pad. Indianapolis is a car-dependent city — parking requirement reflects this. IndyGo bus transit serves limited neighborhoods — parking waiver not widely available.
Restrictions & Requirements
- ADU must be on same lot as primary single-family or duplex dwelling
- Maximum one ADU per lot in D-1 through D-5 dwelling zones
- ADU cannot be separately sold or conveyed apart from primary lot
- Total impervious coverage limits apply per UDO zone requirements
- ADU must have independent entrance from primary dwelling
- Alley-access carriage houses must maintain 3 ft clearance from alley right-of-way
How Many ADUs Are Allowed?
Number of ADUs Allowed in Indianapolis: Single-family lots: 1. Multifamily properties: Per D-6, D-7, D-8 zone density allowances. Indianapolis allows one ADU per single-family lot in D-1 through D-5 zones. Higher density D zones (D-6 through D-8) allow multifamily with density based on lot area. Indianapolis has been exploring expanded ADU provisions as part of housing affordability initiatives.
Single-Family Lots
1
Multifamily Properties
Per D-6, D-7, D-8 zone density allowances
Historic District Considerations
Historic District Requirements: Indianapolis has 10 historic districts where additional design review may be required for ADU construction. Design review approval is required before obtaining a building permit for properties in historic overlay zones. Indianapolis has several locally designated historic districts and overlay zones administered by the Indianapolis Historic Preservation Commission (IHPC). Major areas include Old Northside Historic District, Lockerbie Square Historic District, Irvington Historic District, Meridian Street Preservation Commission area, and portions of Fountain Square and Massachusetts Avenue corridors. Certificate of Appropriateness (CoA) required from IHPC for exterior alterations in designated areas. Indianapolis Historic Preservation Commission holds monthly public hearings. Source: https://www.indy.gov/agency/historic-preservation-commission Look up historic district boundaries at: https://www.indy.gov/agency/historic-preservation-commission
Frequently Asked Questions
Can I build an ADU in Indianapolis?
Yes. Indianapolis, IN allows accessory dwelling units. On a single-family lot you can build 1.
How big can an ADU be in Indianapolis?
The maximum size for a detached ADU in Indianapolis is 900 square feet.
How long does it take to get an ADU permit in Indianapolis?
The typical ADU permit timeline in Indianapolis is Indianapolis-Marion County Department of Metropolitan Development (DMD) processes permits. Typical timeline: 3-6 weeks for zoning certification, 2-4 weeks for building permit. Indianapolis Access (indygo.indy.gov portal) available for online applications. Simple ADU/garage apartment projects may qualify for expedited review.. Total estimated permit fees are $700–$4,000 total fees.
Do I need extra parking for an ADU in Indianapolis?
No, Indianapolis does not require additional parking for ADUs.
Do I have to live on-site to have an ADU in Indianapolis?
No, owner-occupancy is not required for ADUs in Indianapolis.
Source: Indianapolis-Marion County Unified Development Ordinance (UDO) — Accessory Dwelling Unit Standards; Indiana Code Title 36-7. Last verified April 6, 2026. View source