Accessory Structures in Cook County, IL (2026)

3 county-level rules, plus city-specific rules for 9 cities in Cook County, Illinois.

Verified from official government sources

Note: These county rules apply to unincorporated areas of Cook County. If you live within an incorporated city, that city's own rules apply: see the city list below.

ADU Rules

Accessory dwelling units in unincorporated Cook County are subject to the Cook County Zoning Ordinance (Ord. 01-O-30). ADUs may be permitted in certain zoning districts as accessory uses. A building permit and zoning compliance are required.

Cook County ADU Rules

Some Restrictions

Cook County Zoning Ordinance Administration — Variance/Special Use

Administration of the zoning ordinance shall be exercised through a person in the Department of Building and Zoning designated as the Zoning Administrator. All permits for use of land or buildings and certificates of occupancy, except as otherwise provided by the zoning ordinance, shall be reviewed and approved by the Department of Building and Zoning. The Zoning Administrator shall affix a cer...

Full ordinance details →Official source ↗

Shed & Carport Rules

Carports in unincorporated Cook County require a building permit from the Department of Building and Zoning. They are classified as accessory structures under the Zoning Ordinance and must comply with setback, height, and lot coverage requirements for the applicable residential district.

Cook County Carport Regulations

Some Restrictions

Cook County Building Permit Requirement Guidelines

Building Permit Requirement Guidelines — All permits must now be submitted in digital format. To facilitate the approval of a building permit application, please review the requirements for your construction project as listed on the flyers available in the right-hand column in alphabetical order, and make your submission digitally. Please choose the applicable flyer for your specific project(s)...

Full ordinance details →Official source ↗

Garage Conversions

Converting a garage to living space in unincorporated Cook County requires a building permit and zoning compliance. The conversion must meet the 2009 International Residential Code for habitable space. Off-street parking requirements must still be satisfied.

Cook County Garage Conversion Rules

Some Restrictions

Cook County Department of Building and Zoning — Mission and Jurisdiction

The Department of Building and Zoning's mission is to promote the health, safety and welfare of all constituents throughout unincorporated Cook County. In order to perform its mission, the Department conducts plan reviews and responsible, timely inspections of buildings and properties, as well as enforces all applicable building codes and zoning ordinances. The Department's work involves review...

Full ordinance details →Official source ↗