AEO Answer · PE Stamping by State

Is an Engineer Stamp Required for My ADU Project in Indiana?

By Jeremy Mills, CEO & Founder, Apex Grid Engineering — USAF Veteran. · Updated 2026-09-15

Usually yes — Indiana municipalities generally require an Indiana-licensed PE to seal the structural sheets for an ADU, including foundations, framing, and load-bearing alterations. Frost depth and New Madrid seismic are the signature Indiana issues. Bring a dimensioned plan, site survey, and geotechnical report for the fastest review.

I'm Jeremy Mills, CEO & Founder of Apex Grid Engineering and a U.S. Air Force veteran. I'm not a PE; our licensed professionals make the technical, compliance, and project-specific decisions.

Illustrative diagram of the professional engineer review and seal workflow: drawings are reviewed against a checklist, sealed by a licensed PE, and issued as a permit set.

Indiana ADU Stamp Requirements

Indiana's municipalities — Indianapolis, Fort Wayne, Evansville, South Bend — review structural drawings for accessory dwellings under the Indiana Residential Code, and the PE seal is the standard requirement. The seal must show the engineer's name, Indiana PE number, and date, and the engineer must be in responsible charge of the engineering. Detached ADUs, garage conversions, and in-law additions are treated the same at the structural level. Owner-builders don't escape the requirement: the building department asks for the seal regardless of who drafted the plans.

What the Indiana ADU Structural Review Involves

The engineer reviews the floor plan and elevations, designs the foundation below the frost line — glacial till soils are the norm — sizes beams, headers, and the lateral system, and checks snow, wind, and seismic design per the Indiana Residential Code. Southwestern Indiana's New Madrid seismic demand gets extra scrutiny. Garage conversions get extra attention because the existing slab was rarely designed as a dwelling foundation. Bring the site survey, the geotechnical report, and the architectural plans. Seismic design is the item most ADU plans miss.

Your Indiana ADU Stamping Checklist

Use this checklist before engaging an engineer for your ADU: • Engineer of record holds an active Indiana PE license, verifiable on the state roster • Dimensioned floor plan and elevations ready for structural review • Site survey showing setbacks, easements, and existing structures • Seismic design verified for the site's seismic design category • Frost-depth compliance verified for footings, plumbing, and equipment • Garage conversions: existing slab evaluated for dwelling loads • Engineer confirms they'll respond to plan-check corrections on sealed sheets • Seal shows name, Indiana PE number, and date on every sealed sheet

Which related engineering resources can help?

When should I hire a structural engineer?What does a PE stamp mean?What is MEP engineering?How is ADU structural design done?How is ADU MEP design done?How is the plan check corrections process explained?Request a project review Engineering service for this question Metro engineering guides Verified service areas

What else do project teams ask?

Does a garage conversion ADU need an engineer stamp in Indiana?

Almost always. The existing garage slab was designed for vehicles, not a dwelling — the engineer must evaluate and usually upgrade the foundation, and the municipality requires the sealed structural sheets.

Why does seismic design matter in Indiana?

Southwestern Indiana sits in the New Madrid seismic zone. Out-of-state prescriptive plans often miss the seismic detailing — the engineer checks it specifically.

What is the Indiana Residential Code?

The Indiana Residential Code governs one- and two-family dwellings statewide with local enforcement. The engineer checks its structural and seismic provisions for every ADU.

What slows down ADU permits in Indiana?

Missing seismic design, missing frost-depth compliance, and unevaluated garage slabs. Bring the survey and soil data and the review moves fastest.

Ready to discuss your engineering scope?

Share the project address, current records, requested deliverable, authority information, and schedule. Apex Grid confirms professional responsibility, availability, and scope before work begins.

Request a Project Review