Chicago ADU Permit: Rules, Costs & Wait Times

Short Answer

Yes, two steps

Chicago allows coach houses and conversion units only where its Additional Dwelling Units Ordinance permits them: by right in multi-unit and some business and commercial districts, and in RS-1, RS-2 and RS-3 districts only inside an ADU-Allowed RS Area. Every ADU first needs a pre-certification from the Department of Housing, then a plan-based building permit from the Department of Buildings.

Source: City of Chicago: Additional Dwelling Units Ordinance Requirements (linked under Sources below)

Chicago ADU Permits at a Glance

ADU permits, last 12 months: 67
Median application to issue: 96 days
Slowest quarter took at least: 155 days
New detached ADUs: 17

Of the 7 cities we track for ADUs, Chicago ranks 2 of 7 by median wait. The median declared job value on these permits was $147,500.

Who Can Apply and Do the Work

Plans for the building permit must be prepared by an Illinois-licensed architect or structural engineer. Construction of a coach house must use Registered Apprenticeship Programs. Some lots need an administrative adjustment from the Department of Planning and Development, which carries a $500 fee.

What You Need Before the Permit Is Issued

Check whether the lot is in an ADU-Allowed RS Area if it is zoned RS-1, RS-2 or RS-3.
Know the annual block caps in RS districts: 1 pre-certification per block per year in RS-1, 2 in RS-2 and 3 in RS-3.
Check whether owner occupancy is required in your area.
Only one coach house is allowed per lot, and it can only be built after the principal building.
Coach houses built after 2021 cannot be used as short-term rentals; no extra parking is required.

What Else to Know in Chicago

Repairing, remodeling or adding to a legally established coach house does not need a DOH pre-certification. The ordinance treats conversion units (inside the existing building, often a basement or attic) and coach houses (detached) under different rules, so confirm which one you are building before you apply.

Chicago ADU Permit Costs

Item	Official figure
Administrative adjustment from DPD, where required	$500

From the official page cited in the Short Answer, checked October 30, 2026.

What Chicago's ADU Permit Data Shows

Type of ADU	Permits	Share
Conversion of a garage, basement or other existing space	46	69%
New detached ADU	17	25%
Attached ADU	0	0%
Junior ADU	0	0%
Not specified in the description	4	6%

ADU Permits Issued per Month

Chicago ADU permits issued per month, Nov 2025 to Oct 2026. Lighter bar = current month to date.

Types are classified from each permit's description. Building permits whose description mentions an ADU, coach house or additional dwelling unit. Data from Chicago Building Permits, October 30, 2025 to October 30, 2026.

Where ADUs Are Being Permitted

Community area	Permits (12 mo)
Community area 22	14
Community area 4	8
Community area 24	7
Community area 6	6
Community area 77	5
Community area 5	5

Recent ADU Permits

Issued	Work as described by the city
2026-10-26	SPR 2019 CBC: INTERIOR RENOVATION OF EXISTING 3-STORY, TYPE 3A CONSTRUCTION, 3 DWELLING-UNIT MULTI-FAMILY RESI
2026-10-22	CONVERSION FROM 2 DU TO 3 DU, INTERIOR RENOVATIONS TO EXISTING BASEMENT FOR NEW ADU CONVERSION UNIT IN AN EXIS
2026-10-22	CONSTRUCT A DETACHED TYPE VA 2-STORY ADU IN REAR YARD WITH 2-CAR GARAGE.
2026-10-16	SPR 2019 CRBC; EXIST. 2 STORY BRICK 2 DU RESIDENTIAL UNIT. ADD NEW ADDITIONAL DWELLING UNIT (ADU) IN BASEMENT.
2026-10-16	SPR 2019 CBC: FULL BUILDING PERMIT FOR THE CONSTRUCTION OF A NEW 2-STORY DETACHED ADU CONSISTING OF ONE (1) NE
2026-10-14	SPR 2019 CBRC CONSTRUCT A 2 STORY REAR TYPE VA FRAME ADU COACH HOUSE WITH A 2 CAR GARAGE. NO WORK TO THE EXIST

How to Get an ADU Permit in Chicago

Confirm what your lot allows. Zoning, existing unit count, hillside, fire and historic status decide which ADU types and how many you can add.
Choose the program and plans. Decide between the State program and the Local program; they cannot be combined.
Complete the prerequisites listed above before you file.
File the building permit through PermitSF, over the counter or for in-house review.
Build, pass inspections and get final sign-off before anyone moves in.

Frequently Asked Questions

Do I need a permit to build an ADU in Chicago?

How long does an ADU permit take in Chicago?

For the 67 ADU permits issued between October 30, 2025 and October 30, 2026 with both dates published, the median time from application to issue was 96 days, and a quarter took 155 days or longer, according to the city's open data.

How many ADU permits does Chicago issue?

67 in the 12 months to October 30, 2026. About 69% converted existing space such as a garage, 25% were new detached units, 0% were attached and 0% were junior ADUs, based on the permit descriptions.

Can I build a coach house anywhere in Chicago?

No. In RS-1, RS-2 and RS-3 districts the lot must be in an ADU-Allowed RS Area, and annual per-block caps apply; multi-unit and some business and commercial districts allow ADUs by right.

Do I need a permit to renovate an existing Chicago coach house?

You need the usual building permit, but repairing, remodeling or adding to a legally established coach house does not need a Department of Housing pre-certification.

Written and maintained by the Home Permit Guide Editorial Team

Last updated October 30, 2026

Every rule on this page links to the official source it was checked against. Read our Editorial Policy.

Sources

Official sources checked on October 30, 2026. Rules change; confirm with the department before you start work.

City of Chicago: Additional Dwelling Units Ordinance Requirements (chicago.gov)
City of Chicago: ADU Process (chicago.gov)
Chicago Building Permits (data.cityofchicago.org)