What's Required in Indianapolis
- Secondary dwelling unit allowed as an accessory use only in D-A, D-S, D-1 through D-5II, D-8, MU-2 and MU-3 (Table 743-1)
- One unit per lot with a single-family detached dwelling; maximum 720 sq ft; owner must occupy one of the two units as permanent residence
- One additional off-street parking space; separate entrance (attached: different side, or materials or a 3 ft change in plane; detached: visible from the street)
- Detached unit counts toward accessory-building area unless above an existing accessory building; must be lower and smaller than the house and 5 ft from the rear lot line
- New detached unit: ILP ($32 + $108), structural accessory permit ($40 + $150 + $300), plumbing $185, electrical $202, combined HVAC $185
- Conversion within the existing house: structural remodel ($40 + $150 + $200), plumbing $153, electrical $169, heating $153; no ILP
- Sewer lateral permit from Citizens Energy Group for a new secondary residence; septic permit if a bedroom is added on septic
- Plans: site plan at 1 in = 30 ft, floor plan with legend and egress windows, wall section, foundation plan, truss specs, energy code pathway
- Craft permits pulled by licensed plumbing, electrical and HVAC contractors (owner-occupants need board approval for electrical and HVAC)
Can You Build an ADU in Indianapolis?
Yes, in most single-family districts, and the zoning ordinance calls it a secondary dwelling unit: a dwelling unit that is subordinate and accessory to a single-family detached dwelling. Table 743-1 lists it as an accessory use in the D-A, D-S, D-1 through D-5II and D-8 dwelling districts and the MU-2 and MU-3 districts; not in D-6 through D-7 or D-9 through D-11. The use-specific standards (Sec. 743-306) set the limits: one unit per lot per single-family detached dwelling; a maximum size of 720 square feet; the owner must occupy either the primary or the secondary unit as their permanent residence; one additional off-street parking space; and a separate entrance, which for an attached unit must be on a different side of the house or distinguished by materials or a 3 foot change in plane, and for a detached unit must be visible from a right-of-way. A detached unit counts toward the lot's allowable accessory-building area unless it sits above an existing detached accessory building, and in the Compact Context Area a detached unit may only be inside a permitted accessory building.
Indianapolis ADU Permit Rules by Scenario
| What you are doing | City filing | Rule |
|---|---|---|
| New detached unit in the backyard, up to 720 sq ft | ILP ($140) + structural ($490) + plumbing ($185) + electrical ($202) + HVAC ($185) = $1,202 | 2026 fee schedule; Citizens Energy sewer lateral permit |
| Unit above an existing detached garage | ILP ($140) + structural accessory remodel/addition ($390) + trade permits | Does not count against accessory-building area |
| Basement, attic or garage conversion inside the existing footprint | Structural remodel ($390) + plumbing ($153) + electrical ($169) + HVAC ($153) = $865 | No ILP: enclosure of a building that already has a foundation and roof |
| Attached addition for the unit, with remodel of the house | ILP ($140) + structural ($590) + trade permits | Addition and simultaneous remodel of a primary Class 2 structure |
| Second unit on a lot that already has one, or a unit over 720 sq ft | Not allowed without a variance ($550 + $29 per standard) | Sec. 743-306 secondary dwelling unit standards |
| Owner lives elsewhere and rents both units | Not allowed | Owner must occupy one unit as permanent residence |
| Lot in D-6, D-7, D-9, D-10 or D-11 | Not a listed accessory use; variance of use needed | Table 743-1 |
How Much Does an ADU Permit Cost in Indianapolis?
Every Department of Business and Neighborhood Services (DBNS) permit is a flat fee under the January 5, 2026 schedule, and the unit needs five of them. A detached new unit: Improvement Location Permit for a single-family accessory building, $32 application plus $108 ($140); structural permit for construction of an accessory Class 2 structure, $40 application, $150 plan review and $300 issuance for 200 to 1,000 square feet ($490); plumbing permit for a new residential structure, $185; electrical permit for a new structure, $202; combined heating and cooling permit, $185. That is $1,202. A conversion inside the existing house needs no ILP, and uses the remodel lines: structural remodel $40 + $150 + $200 ($390), plumbing alteration $153, electrical repair or alteration $169, heating or cooling $153 (combined system $185), for $865 to $897. Outside DBNS, a new secondary residence needs a sewer lateral permit from Citizens Energy Group, and a new bedroom on a septic lot a county septic permit. No impact fee appears on the DBNS schedule.
What Has to Be in the Application?
The ILP comes first and the structural permit issues after it. The ILP needs a site plan at 1 inch = 30 feet showing the unit, its distance to every lot line (at least 5 feet from the rear line and inside the district's front and side setbacks), the parking space and the entrance. The structural permit needs a floor plan with a legend, room uses, smoke detectors and egress windows labeled in bedrooms; a complete wall section; a foundation plan; framing details; sealed truss specs if used; and a declared Indiana Residential Energy Code pathway (prescriptive, Total UA with a REScheck report, or performance), reviewed to the 2020 Indiana Residential Code. Owners pull the structural permit for their own work with a Statement of Intent; otherwise a listed contractor applies. Plumbing permits go to a state-licensed plumber registered with the city, and electrical and HVAC permits to city-licensed contractors unless the owner-occupant has the board's written approval.
Inspections and Closing Out
Foundation before the pour, each craft's rough-in before concealment, a frame inspection before drywall, and finals requested with the Completion Card within 14 days of finishing. Indianapolis issues no certificate of occupancy; the Completion Card is the close-out.
How to Get a ADU Permit in Indianapolis
Confirm the district and the lot
Check MapIndy for D-A, D-S, D-1 to D-5II, D-8, MU-2 or MU-3; confirm you will live on the lot and that the unit fits 720 sq ft, the parking space and the accessory-area limits.
Get the sewer lateral permit
Apply to Citizens Energy Group before the structural permit; add a county septic permit if the lot is on septic and gains a bedroom.
File the ILP in Accela Citizens Access
Site plan with setbacks, the parking space and the entrance; pay $32 plus $108. The structural permit cannot issue until the ILP does.
File the structural permit and have the trades file theirs
Full plan set with energy pathway, $40 application plus $150 review; licensed plumber, electrician and HVAC contractor pull the $185, $202 and $185 craft permits.
Inspect through to the Completion Card
Foundation, rough-ins, framing and finals; return the Completion Card within 14 days of finishing. No certificate of occupancy is issued.