Permit Required? Required
Typical Fee Range $1,800–$3,650 (Base Permit) Base fee of $1,800 applies for adding a dwelling unit per the 2026 fee table amendment.
Fee Method Project-based
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What's Required in Chicago

  • ADUs are permitted by-right in all multi-unit and some business districts (April 2026 ordinance).
  • Must be located on a lot with an existing residential structure (Conversion or Coach House).
  • Maximum of two units allowed per ADU project depending on ward and lot density.
  • Projects with two or more ADUs must reserve 50% as legally affordable (60% AMI or less).
  • Coach houses cannot exceed 700 sq ft of total floor area.
  • Parking requirements for ADU units are waived citywide under the new ordinance.

How Much Does an ADU Permit Cost in Chicago?

Budget $1,800–$3,650 (Base Permit) for the Chicago permit itself (project-based), issued by the Chicago Department of Buildings — but treat that as the entry fee, not the total. ADUs are full dwelling units, so the permit stack usually includes building, electrical, plumbing, and mechanical trade permits, plus plan review. One local note: base fee of $1,800 applies for adding a dwelling unit per the 2026 fee table amendment. Get an itemized fee estimate from the department before finalizing your budget; the spread between a simple conversion and a new detached build is wide.

ADU Size Limits and Zoning Rules in Chicago

Before drawing plans, check the two gates that sink most ADU projects: size and zoning. Size ceilings vary by lot and ADU type (attached, detached, or conversion), so confirm your specific configuration. Other recorded conditions: must be located on a lot with an existing residential structure (Conversion or Coach House); parking requirements for ADU units are waived citywide under the new ordinance. Setbacks, height limits, and utility connections layer on top of those rules. The Chicago Department of Buildings can confirm what your specific lot allows — worth doing before you pay for architectural drawings rather than after.

How to Get a ADU Permit in Chicago

1

Step 1: Check Eligibility Map

Verify your ward is included in the expanded 34-ward zone (as of April 2026).

2

Step 2: Hire Architect

Full architectural and MEP plans are required for all newly established dwelling units.

3

Step 3: Plan Review Submission

Submit through the Standard Plan Review process via ProjectDox.

4

Step 4: Fee Payment

Pay the $600 deposit followed by the $1,800 minimum unit-creation fee.

5

Step 5: Final Certificate

Obtain final inspections and a new Certificate of Occupancy for the ADU.

Frequently Asked Questions

Yes, under the April 2026 expansion, coach houses are allowed by-right in eligible residential zones.
The base permit fee starts at $1,800, but total costs including plans and trades often exceed $5,000.
No, the 2026 ordinance specifically waives parking requirements for ADUs.