Accessory Dwelling Units

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.

4-minute ADU explainer video

Get building

1. Check your address

Look up an address to check eligibility

2. Review city guidance

Chicago's official info

Find the intake form here

3. Contact an architect or builder

Directory of ADU designers & builders

More resources


10 ADU permits have been issued as of November 8, 2021

Construction & consultation grants are open (Nov. 9, 2021)

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.