Accessory Dwelling Unit/Accessory Conversion Unit Issue Summary


An Accessory Dwelling Unit (ADU) is a legal and regulatory term for a secondary house or apartment that shares the building lot of a larger, primary house. An ADU can be a tiny house in the backyard, a coach house, a granny flat, a build-out space in the basement of a multi-unit or space above a garage.

In 1957, ADUs were deemed illegal in Chicago, but on December 16, 2020, ADUs were made legal. In Chicago, ADUs will be referred to as Accessory Conversion Units (ACUs). The ordinance is effective now, but the Department of Buildings will not issue permits until May 2021.

The current ordinance allows for ACUs in pilot zones. The ordinance does not allow building throughout Chicago under the authority of this ordinance, however, an ACU may be pursued as a zoning variance in areas outside of the pilot zones.

Highlights of the Ordinance

  • The initial registration fee is $500 per unit.
  • An ACU is barred from being listed on any short-term rental platform.
  • An ACU is only eligible for primary structures that are 20 years old or older.
  • If two or more ACUs are erected/created, an Affordable Housing standard is imposed.
  • To comply with the Affordable Housing Average Median Income (AMI) requirements, a two-person occupancy income cannot exceed $43,680 (60% of AMI).
  • ACUs created in the West, South and Southeast zones have an owner-occupancy requirement.
  • While the ordinance does not call for aldermanic approval, applicants must provide written notice to abutting property owners and the alderman. However, the ordinance does not address objections made by the alderman or neighbors.
  • The Department of Housing Commissioner has rulemaking authority.
  • The building of an ACU will require engagement with both the Departments of Building and Housing.

Legislative History

The matter was heard in the City Council in a joint committee, Joint Committee of Housing and Real Estate; Zoning, Landmarks and Building Standards. The first committee meeting occurred on July 10, 2020. The initial proposal was met with much pushback from the committee members. The subsequent meeting scheduled for July 21, 2020 was canceled. Due to the City Council’s focus turning towards the City’s budget, there was no further discussion until December.

The ordinance was re-written, addressing many of the objections raised in July, was re-heard on December 15 and passed the Joint Committee. The ordinance was adopted by the Chicago City Council the next day. One of the biggest changes was the creation of pilot zones, as the initial draft called for as of right building city-wide. The revision created pilot zones.

17-7-0572 Boundaries. Additional Dwelling Unit-Allowed Areas are defined and identified, as follows:

  • North Zone is bounded by Devon, the lakefront, Lawrence, Clarendon, Halsted, Diversey, Lincoln, Belmont, the North Branch of the Chicago River, the North Shore Channel, Peterson, California, Granville, and Seeley.
  • Northwest Zone is bounded by the Eisenhower Expressway, Sacramento, Fulton, Damen, Chicago, Western, Hirsch, Rockwell, North, Sacramento, Bloomingdale, Kedzie, Palmer, Kostner, Fullerton, Central Park, Belle Plaine, Lawndale, Montrose, Harding, Lawrence, Kedzie, Elston, California, Fullerton, Western, North, and Ashland.
  • West Zone is bounded by the Eisenhower Expressway, Homan, the South Branch of the Chicago River, and 4600 West.
  • South Zone is bounded by Cicero, 7500 South, Kedzie, 71st St., Halsted, 63rd St., 600 West, 47th St., King, 60th St., Dorchester, 65th St., Cottage Grove, 67th St., the Dan Ryan Expressway, 95th St., Ashland, and 87th St.
  • Southeast Zone is bounded by 8300 South, the city limits, Torrence, 95th St., Commercial, 83rd Pl., and Houston.

The ordinance is effective now but the Department of Buildings will not issue permits until May 2021.

Our Stance

Accessory Dwelling Units help increase the housing supply, and REALTORS® firmly support policies that encourage building and construction.