# Build an ADU in Chicago Chicago's accessory dwelling unit (ADU) ordinance took effect in five pilot areas on May 1, 2021, permitting additional dwelling units in existing houses and the construction of coach houses in backyards. On April 1, 2026, that pilot program was converted to a permanent one and the eligibility expanded from about 12 percent to 60 percent of the city. **  *Katherine Darnstadt talks about the coach house in the background that her firm, Latent Design, designed for a Lakeview resident's mother.* ## Start here 1. [Read our ADU FAQ](https://chicagocityscape.com/blog/chicago-will-allow-adus-starting-in-may-read-our-faq-c44b989ccb) 2. **Look it up**: Check your property's ADU eligibility by using the [Property Report](https://www.chicagocityscape.com/address.php?src=adu_portal) (this works for previous code as well as the current code that took effect April 1, 2026) 3. **Talk to an architect**: Contact an [ADU designer](https://www.chicagocityscape.com/adu/serviceproviders.php) to discuss building an ADU at your residentially-zoned property 4. [Review guidance](https://www.chicago.gov/city/en/sites/additional-dwelling-units-ordinance/home.html) by the City of Chicago, where you will also find the intake form to obtain pre-approval prior to filing a building permit application Tip: [Not eligible? Here's how to build an ADU outside a pilot area](https://help.chicagocityscape.com/unusedzoningcapacity) by taking advantage of #UnusedZoningCapacity ## Chicago zoning code After reading our FAQ, refer to the Chicago Zoning Ordinance ("zoning code") to learn all of the standards for compliance. - [Code section on coach houses (17-9-0201-F)](https://codelibrary.amlegal.com/codes/chicago/latest/chicago_il/0-0-0-2529351) - [Code section on conversion units (17-9-0131)](https://codelibrary.amlegal.com/codes/chicago/latest/chicago_il/0-0-0-2529351) Starting April 1, 2026, about 60% of the city's ADU-eligible land area allows ADUs — either by right in RT, RM, B, and C zoning districts, or in RS-zoned areas that are within an aldermanic opt-in area. [[ADU coverage analysis|See how we calculated this]]. ## Additional resources Alternatively, find eligibility and additional information on [ADU Checker](https://aduchecker.com), a third-party website. ### Design - Measure your basement or backyard space: basement units need at least 7 feet of clearance between the finished floor and finished ceiling. See [[ADU ceiling height|Minimum ceiling heights for basement ADUs]]. - [Review the "Better Basement Units" manual](https://nhsbasementmanual.azurewebsites.net/) created by Neighborhood Housing Services (NHS) - [[Zoning worksheet for coach houses]] learn how to determine how big of a coach house you can build ### News and updates - The Illinois legislature is considering two bills to legalize ADUs statewide in 2026: [SB 4071](https://www.ilga.gov/Legislation/BillStatus?DocNum=4071&GAID=18&DocTypeID=SB&SessionID=114&GA=104) and [HB 5626](https://www.ilga.gov/Legislation/BillStatus?DocNum=5626&GAID=18&DocTypeID=HB&SessionID=114&GA=104) ([read more](https://yimbyaction.org/blog/illinois-build-plan/)). Abundant Housing Illinois is supporting both bills. - Tour a new construction coach house ([video from November 2023](https://www.chicagocityscape.com/blog/video-tour-a-new-construction-coach-house-in-lakeview-8d529d4af4)) - Designers, lenders, and city staff gather to discuss current, future ADU policy ([read the report about this event in April 2023](https://www.chicagocityscape.com/blog/designers-lenders-and-city-staff-gather-to-discuss-current-future-adu-policy-9c0690e94e)) - In August 2022 we [toured three ADUs](https://twitter.com/ChiBuildings/status/1563593603242676224) of various types and degrees of completion in Evanston - A Zillow survey found [71% of respondents in Chicago](https://www.zillow.com/research/modest-densification-zhar-30934/) supported allowing ADUs in residential areas. - [Preservation professionals are overwhelmingly in favor of ADUs](https://www.placeeconomics.com/results-of-adu-prespoll/) #### Data and maps - [Refer to our ADU Data page](https://www.chicagocityscape.com/adu/data.php) which has statistics about the number of ADUs permitted across the city, in Wards, and in State House and State Senate districts. - [View a map of the 5 pilot areas](https://www.chicagocityscape.com/maps/index.php#/?places_type=chicagoadupilotarea) - [Show ADU permits across Chicago](https://www.chicagocityscape.com/permits.php#/?mode=adu) ## Eligible areas (outside Chicago) - [Evanston guide (PDF)](https://www.cityofevanston.org/home/showpublisheddocument/63574/637551285506370000) - [Oak Park guide (PDF)](https://www.oak-park.us/sites/default/files/Housing/2022-03-11-vop-accessory-dwelling-unit-guide.pdf) - [See where else ADUs are allowed in Chicagoland](https://www.cmap.illinois.gov/updates/all/-/asset_publisher/UIMfSLnFfMB6/content/communities-accessory-dwelling-units) ## Related articles - [[Fund & finance an ADU]] - [[Information about accessibility in buildings]]