Accessory Dwelling Units

Look up your address in the search field above to check if it's in one of the 5 pilot areas and it's within a RS-2, RS-3, RT, or RM zoning district.

Accessory dwelling units (ADUs) are now legal in Chicago from Steven Vance on Vimeo.

Basic info

The City of Chicago adopted an ordinance re-legalizing accessory dwelling units on Wednesday, December 16, 2020. It allows a backyard house or interior ADU at properties in one of the 5 pilot areas and also within a RS-2, RS-3, RT, or RM zoning district. Properties with 5 or more units can have 2 or more interior ADUs, but no backyard house.

A triptych of three renderings of a backyard house on a vacant lot (by Booth Hanse); two additional basement units by Civic Projects; and a backyard house on an improved lot by LEVEL.

Get building

The first permits can be applied for and issued on May 1, 2021.

  1. Look up an address to check eligibility
  2. Directory of ADU designers & builders
  3. Chicago's official info Find the intake form here
  4. Watch past webinars

See More resources below

More resources

Understanding the law

Read our FAQ about the adopted ordinance

Read the ordinance: SO2020-2850

Eligible areas

View a map of the 5 pilot areas

Not eligible? Here's how to build an ADU outside a pilot area

Live in Evanston? Read this guide (PDF)

Design ideas

Review the "Better Basement Units" manual from NHS

Zoning worksheet to calculate how large a backyard house can be

Read about the first publicized design for a Chicagoan

News

Preservation professionals are overwhelmingly in favor of ADUs

Data Notes

Where are the most eligible properties?

There are five pilot areas: Southeast, South, West, Northwest, and North. Based on our estimation there are 92,322 eligible properties*. Use the Property Finder tool within each Place Snapshot (linked below) to map and download a list of these properties. They are spread across the pilot areas like so:

Pilot area Quantity
Southeast 10,030
South 37,279
West 9,509
Northwest 15,348
North 20,156

Data notes

A plurality of these properties (49.2%) are in RS-3 zoning districts; 31.1% are in RS-2, and 15.1% are in RT-4. The remaining ~4.6% are in the 7 other "R" zoning districts.

* For our analysis, we included only these property classes (defined by the Cook County Assessor) that have a residential component: 2-11, 2-12, 2-13, 2-25, 3-13, 3-14, 3-15, 3-18, 3-91, 3-96, 4-18, 9-00, 9-13, 9-14, 9-15, 9-18, 9-91, 9-96, 9-97, 2-02, 2-03, 2-04, 2-05, 2-06, 2-07, 2-08, 2-09, 2-34, 2-78.

We also excluded condo buildings. Condo associations are allowed to participate, but the legalities and likelihood of doing so is up to each association and their rules. Vacant lots were excluded, too; a backyard house is allowed to be built first on a vacant lot in only the North (203 vacant lots) and Northwest (593 vacant lots) pilot areas.