Chicago Accessory Dwelling Unit Guide
Data version: Q2 2026 · Last updated 2026-05-13
Buildability City Score™: C+ (Middle 52%) · Median permit time: 96 days
TL;DR. Find out if your Chicago property qualifies for an accessory dwelling unit. Buildability™ checks the local ADU ordinance, Illinois state law, your zoning district, lot size, setbacks, parking requirements, and owner-occupancy rules in about 20 seconds. Free for your first check.
Chicago ADU rules at a glance
Chicago follows local ordinances layered on top of Illinois state ADU law. Typical restrictions cover maximum size (often 800–1,200 sqft), height (16–25 feet), side setbacks (4 feet minimum in most jurisdictions), parking (often waived near transit), and owner-occupancy. Buildability™ reads Chicago's specific code against your exact lot.
Why this matters
Most Chicago homeowners don't discover their ADU is infeasible until they've spent $3,000+ on preliminary design. Buildability™ catches the blockers first — easements, overlays, wetland proximity, utility extension costs — so you don't waste soft costs on a dead-end project.
How Buildability™ checks your Chicago property
Enter any Chicago address. Buildability™ pulls zoning, lot dimensions, easements, environmental overlays, utility access, and current Illinois state ADU law. Results include your Buildability Score™, setback envelope, maximum ADU size, parking waiver eligibility, and an estimated permit timeline — in about 20 seconds. Free for your first check.
Help us keep this accurate
Buildability™ translates Chicago's ADU rules in plain language. Rules change and overlays are sometimes missed — if you spot an error on this page, email team@buildability.us with the URL and what's off. We verify with the Chicago planning department and update within 48 hours of a confirmed correction. Chicago planning staff: the same email works if you'd like to flag corrections or set up a direct verification channel.
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