The Chicago Zoning Ordinance and related zoning laws are complex and often confusing. As with much of Chicago governance, the system is part rule of law and part political tradition.

It is important to understand the principle of “Aldermanic prerogative”. Under this often unwritten practice, the city council members (Alderman) can unilaterally initiate or block city government actions that impact their wards.  According to Encyclopedia of Chicago, since the mid-19th century, alderman have had the right of first approval over street improvements, liquor licenses, and zoning matters.  Specifically, as it applies to zoning, a developer must seek and receive support for his project from the Alderman before the administrative process begins.

After receiving this support, the developer submits a zoning amendment application to the zoning committee, along with notice of the change by regular mail to parties within 250 feet of the property line.  The alderman at his discretion may elect to have a public meeting.  The zoning committee meets every 30 days and must approve the change before submission to the full city council.  Both the zoning committee and the city council adhere closely to the alderman’s prerogative and will generally approve the change.  Both bodies are required to hear public testimony if offered.  Upon passage by the city council, the zoning change becomes law.

Zoning Glossary 

AS-OF-RIGHT:  What is allowed under current zoning 

AFFORDABLE HOUSING ORDINANCE:  or Affordable Requirements Ordinance (ARO)

The ARO is designed to economically blend rental or owner-occupied market rate developments to allow for occupancy by qualified individuals or families at an affordable rate.  It impacts new or existing residential developments which add 10 or more units and require new zoning, city land purchase or city financial assistance.

The Avondale Zoning Committee supports the ARO pilot program where the unit obligation would go from 10 percent to 15 percent (or 20 percent if the developer builds offsite). At the same time, the number of households eligible would also climb, to include those who earn up to 80 percent of area median income ($50,600 for a two-person household).

ALDERMANIC PREROGATIVE  Deference by the full city departments, committees, and the full council to aldermen on city government actions within their wards, including zoning

DENSITY:   The maximum number of dwelling units permitted on a zoning lot, which combines an estimate of the average unit size and allowances for common areas;  also expressed as floor area ratio (FAR) and minimum lot area (MLA).

FAR (FLOOR AREA RATIO): The ratio of the total square footage of buildings built on a lot divided by the total square footage of the lot. This is essentially how many square feet a developer may build per square foot of land he owns. For example, a 3,125 SF lot (standard 25’ x 125’ Chicago lot) zoned RS-3 allows a FAR of 0.9. This means the developer may construct a building up to 2,812 SF (3,125 x 0.9) under that zoning.

LANDMARK: A special designation that protects the historic features of a building from demolition or modification. Landmark designation also carries a significant property tax freeze to reward the owner for protecting their landmark.  

LANDMARK DISTRICT: A zoning overlay that protects all or many buildings in a specific area from demolition or modification. Buildings deemed to be “contributing” to the district are protected. The only Landmark District currently in Avondale is the Milwaukee/Diversey/Kimball district which protects the variety of excellent historic commercial buildings at that corner.

LETTER OF SUPPORT: A letter from the Alderman publicly supporting a proposed zoning change that is almost always required before the City Council will approve the proposed change.

MLA (MINIMUM LOT AREA): The minimum SF of land per unit allowed on a lot. This is the ratio between the total number of units allowed on a lot and the lot’s area. For example, if you have a 3,125 SF lot that is zoned with a district that has an MLA of 1,000, then you would only be allowed to build 3 units (3,125 / 1,000 rounded down) on that lot maximum.

ORANGE RATED: Another zoning overlay that protects a building from being demolished without warning. Many buildings that are not landmarks, but still historically significant or fine examples of their historical style are listed as Orange Rated. An owner of an Orange Rated building will not be issued permits for demolition for 90 days to give preservationists time to respond and save the structure. Orange Rated status was determined by the Chicago Historical Resources survey which canvassed the entire city identifying historic buildings.

PD (PLANNED DEVELOPMENT): A special zoning process that allows developers to tailor individualized construction to a particular lot, essentially for projects that are too big or too complex to fit within any of the existing zoning districts. These are also rare because it is an expensive process that creates a short ordinance describing the special traits the project requires. Typically PD’s are used downtown for projects like the Trump Tower or the entirety of the Lakeshore East neighborhood.

An example of an Avondale project requiring a PD is the “The Fields” redevelopment of the massive Marshall Fields/Olsen Rug building at Pulaski and Diversey.  

P-STREET (PEDESTRIAN STREET):  A zoning overlay meant to protect streets that are heavily trafficked by pedestrians. This prevents new curb cuts (i.e. driveways) from being added and many other minor special requirements.  

SETBACK: The distance from a lot line a property must maintain in order to comply with the specifics of an underlying zoning district. Most zoning districts require some sort of setback whether from the front, rear, or side of the lot, especially if adjacent to low-density residential districts.  

TOD (TRANSIT ORIENTED DEVELOPMENT): A development constructed near transit with greater density and less parking. Chicago recently passed a special ordinance giving bonus density and reducing parking requirements within approximately a ½ mile of train stations.  

ZONING AMENDMENT APPLICATION: A form which must be submitted to the city describing a proposed zoning change. Link to Form on City Website


R – Residential
B – Business
C – Commercial
D – Downtown
M – Manufacturing
PMD – Planned Manufacturing Districts
PD – Planned Development
T – Transportation
POS – Parks and Open Space

A property would be classified as A-B, where A is the zoning district using the codes above, and B is a number that determines such criteria such as floor area ratio, lot area per unit maximum building height, among others.  For example, RS-2 is a single family home district with floor area ratio of .65, a maximum height of 30 feet. and a minimum lot area of 5000 square feet.

For specific zoning district and related size criteria see: www.secondcityzoning

ZONING OVERLAY:  An overlay may refer to any of a number of special districts or protection under the Ordinance. A few examples are landmark districts, the lakefront protection district, TIF districts, and Pedestrian Streets. Any property that falls under one of these special overlays is subject to specific rules for that district regardless of what the underlying zoning is.

Alderman info

30th Ward, Alderman Ariel Reboyras
3559 N. Milwaukee
Chicago, IL 60641
Carlos Cintron, Chief of Staff

31st Ward, Alderman Milly Santiago
2521 N. Pulaski
Chicago, IL 60639
Kevin Lamm, Chief of Staff

32nd Ward, Alderman Scott Waguespack
2657 N Clybourn
Chicago, IL 60614
Elizabeth Gomez, Director of Outreach

33rd Ward, Alderman Deb Mell
3001 W. Irving Park Road
Chicago, IL 60618
Jason Hernandez, Chief of Staff
Zoning and Development Site

35th Ward, Alderman Carlos Ramirez-Rosa
2710 N. Sawyer
Chicago, IL 60647
William Drew, Legislative and Policy Director
Zoning and Development Site