Increasing Affordable Housing Stock: Accessory Dwelling Unit Ordinance Introduced

Posted By: Tom Benedetto Advocacy News,

ADUs in Chicago: Unlocking More Affordable Units

Accessory Dwelling Units (ADUs) Ordinance as introduced by Mayor Lightfoot on May 20, 2020 (O2020-2850)


“The City needs to be creative and realistic about how and where we can increase affordable housing opportunities for renters while also helping property owners deal with the financial demands of their buildings. With this sustainable and cost-effective approach, we are providing residents with more equitable access to affordable housing options citywide.”

Mayor Lori Lightfoot on the proposed ADU ordinance.


The ordinance legalizing these units was referred to a joint-committee on Housing, Zoning, and Buildings. The legislation was sponsored by:

  • Mayor Lori E. Lightfoot
  • Harry Osterman (48) who chairs the Housing and Real Estate Committee
  • Tom Tunney(44), who chairs the zoning committee
  • Walter Burnett(27)
  • Matt Martin (47)
  • Maria Hadden(49)

Zoning: ADUs cannot be added “by right” or “as of right” (without zoning permission). While property owners in “R” zones can choose to add either one or more conversion units or a coach house, landlords who want to do so in RS-1 or RS-2 zones require a special-use zoning permit. Properties that are either vacant or have a single-family house, 2-flat, 3-flat, or 4-flat would be able to add one coach house as long as there is no conversion unit on the lot.

Density: Designated parking spaces are not required for conversion units or coach houses. The ordinance would reduce the required parking for single-family houses in the RS districts from two spaces to one space, allowing the removal of a space in order to flexibly situate a new coach house on a lot. Coach houses can be built as part of new construction, and in vacant lots.

Affordability: Another section of the ordinance would require that any property owner who adds multiple accessory dwelling units to their property would have to charge reduced rents on at least half of the new units, rounding down. If two or more conversion units are being added to a residential building (that has five or more units), either at the same time, or at different times, 50 percent of them (rounding down) have to be rented at an “affordable” price for 30 years. The affordable units must be targeted at renters who make less than 60 percent of area median income (AMI), or about $53,000 for a family of four in Chicago.

For more information on this ordinance, please contact Tom Benedetto (