Chicago ADU Permitting Guide
Your quick reference to Chicago’s Building & Safety Division processes, requirements, and timelines for accessory dwelling units.
Building Code
Contact AHJ
Climate Zone
Varies
Permit Time
Varies
AHJ
Local Authority
The Chicago Department of Buildings, part of the Building & Safety Division, serves as the Authority Having Jurisdiction for all ADU projects in the city. Under Chicago Ordinance 13-215 and the 2021 International Residential Code, homeowners and contractors must meet specific setbacks, parking, and fire‑rating standards before construction can begin. The Division reviews plans for compliance with these local amendments and issues permits that are ready for construction, ensuring each ADU aligns with city safety and zoning goals.
What Your ADU Permit Needs
To start, submit a complete set of construction drawings that show site layout, floor plans, and structural details. The drawings must reference the 2021 International Residential Code and include any Chicago-specific amendments, such as the required 10‑foot side yard setback and the mandatory fire‑rated exterior wall assembly for units attached to existing structures.
In addition to the drawings, provide a site plan with utility locations, a completed zoning verification form, and proof of ownership or landlord consent. All documents are reviewed for compliance with the city's energy code, accessibility guidelines, and storm‑water management requirements before the permit is issued.
Common Project Types
Detached ADU
Standalone accessory dwelling unit built on a separate footprint on your lot.
Attached ADU
Unit sharing a wall with the primary residence, meeting fire‑rating rules.
Garage Conversion
Transform an existing garage into a legal ADU while preserving structural integrity.
Basement ADU
Create a below‑grade living space that complies with egress and moisture standards.
Building Department
- Authority
- Chicago Department of Buildings
- Address
- 121 N LaSalle St, Chicago, IL
- Permit Portal
- Chicago Permit Portal
- Fees
- Permit fees are based on project size and scope; consult the portal for the fee schedule.
Frequently Asked Questions
How long does the first review take for an ADU permit?
The Building & Safety Division typically completes the initial plan‑check review within five business days, provided all required documents are submitted correctly.
Can I submit my ADU plans online?
Yes, you can upload complete construction drawings, site plans, and supporting forms through the Chicago Permit Portal. Online submissions are processed the same way as in‑person filings.
What local amendment should I watch for when designing an ADU?
Chicago requires a minimum 10‑foot side yard setback and a fire‑rated exterior wall assembly for attached units. Review the city’s latest amendment sheet on the portal to ensure compliance.
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