Yes, on most Chicago lots outside the downtown D districts. Since April 1, 2026 (Ordinance SO2024-0008918, passed 46-0 on Sept. 25, 2025) a conversion unit (a basement or attic apartment inside a building at least 20 years old) and one detached coach house are allowed by right on any RT, RM, B1-B3, C1 or C2 lot, and on RS1-RS3 lots inside the ten ADU-Allowed RS Areas in Zoning Ordinance Sec. 17-7-0574 (DOH counts 320,000-plus eligible parcels, up from 116,000 under the pilot). A coach house has no floor-area cap since the pilot's 700-square-foot limit was repealed; it is limited to 22 ft in height, must stand 15 ft behind the main house inside the rear setback area, and needs no parking (Sec. 17-9-0201-F). Getting one built takes an online Department of Housing pre-certification (chicago.gov/adu; proof of owner-occupancy in seven of the ten RS areas), a Department of Buildings permit that cost $2,525-$3,050 for coach houses in 2026 permit records plus a $522 open-space impact fee, and, for a coach house, a contractor enrolled in a federally registered apprenticeship program. Add two or more ADUs and half must rent at 60% of area median income for 30 years; short-term rentals are banned in every ADU.
In Chicago you will also hear an ADU called a coach house — Chicago's century-old name for the unit above a rear garage. The rules on this page apply either way.
Zoning & Size Requirements [1][2][3][4][5][6][7][8][9]
Yes — Chicago allows ADUs. There is no square-footage cap — size is governed by height, setbacks and lot coverage — under current Illinois and Chicago zoning rules.
See what this means for your lot — ask Chicago ADU builders for a quote →
| Allowed Zones | By right in every RT (two-flat, townhouse and multi-unit) and RM (multi-unit) district citywide and in the B1, B2, B3, C1 and C2 business and commercial districts (use tables 17-2-0207 rows 7-8 and 17-3-0207 rows 5-6). In RS1, RS2 and RS3 single-family districts only on lots inside one of the ten ADU-Allowed RS Areas defined in Sec. 17-7-0574 (as replaced by SO2026-0022453, effective April 1, 2026), which the City says cover parts of 34 of the 50 wards; an RS lot outside those areas cannot get a permit (17-9-0131(1), 17-9-0201-F(1)). Shown as not allowed in C3, and the ordinance did not amend the use tables of the downtown D or manufacturing districts. In B and C districts a coach house must sit in the rear 30 ft of the lot, and a conversion unit below the second floor is by right only if 40% of the ground-floor frontage stays commercial (B2 excepted); otherwise it needs Zoning Board of Appeals approval under 17-9-0131(7) |
| Max Size (Detached) | any size that fits the coach house bulk rules; Chicago sets no floor-area cap since the pilot's seven-hundred-square-foot dwelling-unit limit was repealed with the citywide ordinance (effective April 1; see recent changes). What sizes the building: 22 ft height limit, one dwelling unit per coach house, a 15 ft gap behind the main house, the rule that all accessory buildings together may cover no more than 60% of the required rear setback area, and a 3 ft open strip along one side. Coach houses are exempt from floor-area-ratio, lot-area-per-unit and rear-yard open-space minimums but may not eat into open space the main building needs |
| Max Size (Attached) | any size the existing building can provide; a conversion unit has no floor-area cap in the zoning code. It must be inside a principal building that has lawfully existed for at least 20 years (an attic, basement or other space, or a legalized existing unit), is exempt from lot-area-per-unit and open-space minimums, and must meet the Chicago Building Code for a dwelling unit through the DOB permit |
| Max Size (JADU) | Not allowed as a separate category: Chicago has no junior ADU. A small unit carved out of the house is a conversion unit and counts toward the 33% conversion-unit allowance |
| Max Height | 22 ft for a coach house, measured as building height under 17-17-0311, and no rooftop feature may rise above 22 ft either (17-9-0201-F(5)-(6)). Any other accessory building in a required rear setback is capped at 15 ft (17-9-0201-E). A conversion unit takes the height of the existing building |
| Max Units | one coach house per lot (one dwelling unit inside it, regardless of how many units the main building has) plus conversion units equal to 33% of the lawfully established units, rounded to the nearest whole number with a minimum of one: 1-4 existing units add 1, 5-7 add 2, 8-10 add 3, 11-13 add 4 (17-2-0303-C, 17-3-0309, DOH table). A coach house and conversion units may now share a lot. Adding two or more ADUs in any combination makes 50% of them (rounded down) affordable at 60% AMI for 30 years (2-44-106(d)). In RS Areas 3, 4, 5, 8, 9 and 10 no more than 1 (RS1), 2 (RS2) or 3 (RS3) ADUs may be pre-certified per block face plus its opposite face per calendar year |
Setback Requirements [1][2][3][4][5][6][7][8][9]
Chicago requires a rear setback of about 2 ft for a detached ADU, and no additional parking is required. Owner-occupancy is set by local rules (confirm with the city).
| Rear Setback | 2 ft from the rear lot line where the lot backs onto a public alley, waived if the coach house is at least 10 ft from the alley centerline as shown on a survey (17-17-0309). A coach house is one of the few structures allowed inside the required rear setback, but all accessory buildings together may occupy no more than 60% of that setback area (17-9-0201-D). A minimum 15 ft separation is required between the rear wall of the main house and the front wall of the coach house; on lots less than 125 ft deep the Zoning Administrator can cut it to 10 ft by administrative adjustment (17-9-0201-F(8), 17-13-1003-PP) |
| Side Setback | At least 3 ft of open, unobstructed space between the coach house and one side lot line for the full length of that wall, not required where that side line abuts an alley or street (17-9-0201-F(7)). A coach house may not encroach into a required side setback (17-17-0309); the 2021 amendment (O2021-1228) limited the RS side-setback table to the principal residential building, so ask DPD zoning review how the other side is treated on your lot |
| Front Setback | N/A: a coach house is a rear accessory building and may only be built after the main house exists (17-9-0201-F(13)); it may not encroach into the front setback (17-17-0309). In B and C districts it must be within the rear 30 ft of the lot depth (17-9-0201-F(2)) |
| Parking Required | None required for a conversion unit or a coach house (17-9-0131(5), 17-9-0201-F(4)). Parking the main building must keep may be reduced or waived by administrative adjustment when a coach house is built (17-9-0201-F(3), 17-13-1003-OO), so a garage can become the coach house's ground floor or be removed |
| Owner Occupancy | Depends on the zone. Not required on RT, RM, B or C lots or in ADU-Allowed RS Areas 1, 6 and 7. Required at pre-certification when the main building is a detached house in RS Areas 2, 3, 4, 5, 8, 9 and 10 (17-7-0573(2), 17-7-0574): DOH asks for a government photo ID plus a tax bill, utility bill, deed, mortgage statement or insurance declaration for the address. Nothing in the ordinance requires owner-occupancy after the permit issues |
| Min Lot Size | none: conversion units and coach houses are exempt from the minimum-lot-area-per-unit rules of 17-2-0303-A, 17-3-0402-A and the overlay districts (17-9-0131(3), 17-9-0201-F(10)), and coach houses are also exempt from floor-area ratio (17-9-0201-F(12)). The practical limits are the 60% rear-setback coverage rule and the 15 ft separation, so a shallow lot may need the 10 ft administrative adjustment |
Permit Process & Fees [10][11][12][13][14][15][16]
An ADU permit in Chicago goes through a standard permit review. Review time: not published by DOH or DOB. City permit records (Chicago Data Portal, permits issued January-September 2026 for a coach house, conversion unit or ADU) show Standard Plan Review permits issuing a median 120 days after the application date (middle half 78-183 days) and Self-Certification permits a median 58 days (35-98 days); DOB says self-certified applications typically issue within 10 business days after zoning approval. Add the DOH pre-certification review before either. Fees range from $2,525-$3,050 for a new coach house in 2026 permit records (DOB building permit fee minimum $2,450 for new residential construction in Table 14A-12-1204.3(3), plus a $75 zoning review fee on most permits; a few paid $1,500 zoning fees). $1,875-$3,150 for a conversion unit (minimum $1,800 for a permit that adds a dwelling unit, Table 14A-12-1204.3(4), plus zoning). The formula is construction factor x review factor x floor area (14A-4-412.2.2.1; $0.44 per sq ft x 0.75 for a wood-frame Group R coach house), so the minimums govern any ADU-sized project. A $300 deposit is paid at application (14A-12-1204.1). DOH lists no pre-certification fee; an affordable ADU costs $500 to register.
| Approval Process | Two steps, both administrative with no hearing. 1) Department of Housing ADU pre-certification through the online portal at chicago.gov/adu: check the eligibility map, enter the number of existing legal units, the building's age and the ADUs proposed, upload owner-occupancy proof if your RS area requires it and the recorded affordability covenant if you are adding two or more units; the portal emails your alderperson automatically (2-44-106(g)); coach-house applicants must commit that the general contractor and every subcontractor participate in a U.S. Department of Labor Registered Apprenticeship Program; a $500 administrative adjustment through DPD is added in RS Areas 2, 8 and 9. 2) Department of Buildings permit through E-Plan with the pre-certification letter attached: DPD zoning review first, then Standard Plan Review (drawings sealed by an Illinois-licensed architect, a DOB project manager coordinates the technical reviews) or the Self-Certification program (a registered architect or structural engineer certifies code compliance). The Express Permit program does not cover ADUs. Separate electrical, plumbing, water-service and sewer permits follow as needed |
| Review Timeline | not published by DOH or DOB. City permit records (Chicago Data Portal, permits issued January-September 2026 for a coach house, conversion unit or ADU) show Standard Plan Review permits issuing a median 120 days after the application date (middle half 78-183 days) and Self-Certification permits a median 58 days (35-98 days); DOB says self-certified applications typically issue within 10 business days after zoning approval. Add the DOH pre-certification review before either |
| Permit Fees | $2,525-$3,050 for a new coach house in 2026 permit records (DOB building permit fee minimum $2,450 for new residential construction in Table 14A-12-1204.3(3), plus a $75 zoning review fee on most permits; a few paid $1,500 zoning fees). $1,875-$3,150 for a conversion unit (minimum $1,800 for a permit that adds a dwelling unit, Table 14A-12-1204.3(4), plus zoning). The formula is construction factor x review factor x floor area (14A-4-412.2.2.1; $0.44 per sq ft x 0.75 for a wood-frame Group R coach house), so the minimums govern any ADU-sized project. A $300 deposit is paid at application (14A-12-1204.1). DOH lists no pre-certification fee; an affordable ADU costs $500 to register |
| Impact Fees | $522 per new dwelling unit under 800 sq ft in 2026, $1,044 for 800-1,599 sq ft, under the Open Space Impact Fee (Chapter 16-18 as amended in 2024: 87 sq ft of open space per person x $20 per sq ft x a 30% developer share x an estimated household size of 1 under 800 sq ft or 2 for 800-1,599 sq ft); it rises to $626 and $1,253 on Jan. 1, 2027 and a registered affordable ADU pays a flat $100. Both conversion units and coach houses are expressly subject to Chapter 16-18 (17-9-0131(2), 17-9-0201-F(11)). Chicago charges no other development impact fee; water and sewer connection fees are billed separately by the Department of Water Management |
| Plan Check | DPD zoning review comes first on every application; DOB then routes the drawings to its technical reviewers (building, structural, electrical, plumbing, mechanical, fire) through ProjectDox, with the balance of the permit fee due when the permit is ready. Plans must show the DOH pre-certification letter, the coach house height (22 ft), the 15 ft separation, the 60% rear-setback coverage calculation and the alley setback. Chicago has no ADU-specific plan checklist; the Standard Plan Review flowchart and the Self-Cert program pages are the published guidance |
| Pre-Approved Plans | Not available. Chicago has no pre-approved coach house or conversion-unit plan program as of September 2026; DOH's resources page lists guides (the NHS Better Basement Units Guide and a ULI video series) rather than plan sets, so budget for custom architectural drawings |
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Construction Costs [17][18][19]
Building an ADU in Chicago typically costs $150,000-$350,000 ($200-$400 per sq ft); a garage conversion runs $75,000-$200,000.
See what this means for your lot — ask Chicago ADU builders for a quote →
| Average Build Cost | $150,000-$350,000 |
| Cost per Sq Ft | $200-$400 |
| Garage Conversion | $75,000-$200,000 |
| Prefab ADU (Installed) | $125,000-$250,000 |
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Rental Income Potential [20][21][22]
A 2-bedroom ADU in Chicago rents for around $1,800-$2,600/mo, an estimated 8-12% gross rental yield on a $175,000-$300,000 coach house renting at $1,600-$2,200/mo, before taxes, vacancy, insurance and financing; a $65,000-$150,000 basement conversion renting at $1,400-$1,900/mo returns 12-25% g.
| Avg Rent (1 Bedroom) | $1,500-$2,200/mo |
| Avg Rent (2 Bedroom) | $1,800-$2,600/mo |
| Short-Term Rental | No. A conversion unit, or a coach house established after May 1, 2021, may not be rented, leased or offered for transient occupancy as defined in Sec. |
| Est. Annual ROI | 8-12% gross rental yield on a $175,000-$300,000 coach house renting at $1,600-$2,200/mo, before taxes, vacancy, insurance and financing; a $65,000-$150,000 basement conversion renting at $1,400-$1,900/mo returns 12-25% g. |
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Recent Law Changes
What's Changed Recently
- April 1, 2026: Ordinance SO2024-0008918 (Ald. Lawson; passed 46-0 on Sept. 25, 2025) took effect. Conversion units and coach houses are allowed by right in every RT, RM, B1-B3, C1 and C2 district citywide and in ADU-Allowed RS Areas (Sec. 17-7-0570), replacing the five pilot zones of 2021. Repealed: the 700-square-foot coach house cap, the four-unit limit on buildings that can add a coach house, the ban on a coach house and a conversion unit sharing a lot, and the neighbor-notice affidavit. Conversion-unit density is 33% of existing units (minimum one); the 2021 allowance to build a coach house before the main house was reversed
- April 1, 2026: SO2025-0020513 (Dec. 10, 2025) and SO2026-0022453 (Feb. 18, 2026) rewrote the 17-7-0574 table to ten ADU-Allowed RS Areas. Areas 1 (the largest, running along the lakefront and across the Northwest Side), 6 and 7 carry no limitations; Areas 3, 4, 5 and 10 have the annual block cap (1 per block in RS1, 2 in RS2, 3 in RS3) and owner-occupancy; Area 2 owner-occupancy plus a $500 administrative adjustment; Areas 8 and 9 all three. DOH's April 1 launch counted 320,000-plus eligible parcels in 34 of 50 wards, up from 116,000
- April 1, 2026: coach-house labor rule. Under 2-44-106(g)(4) DOH will not pre-certify a coach house unless the owner commits to obligate the general contractor and all subcontractors to U.S. Department of Labor Registered Apprenticeship Programs for the trades on the permit; conversion units are not covered
- Jan. 1-6, 2026: the Open Space Impact Fee on a new unit under 800 sq ft rose to $522 ($1,044 for 800-1,599 sq ft) under the 2024 rewrite of 16-18-040, and DOB's 2026 permit fee tables (amended Jan. 6, 2026) set a $2,450 minimum for new residential construction and $1,800 for adding a dwelling unit. City permit data through September 2026 show 55 coach-house, conversion-unit or ADU permits issued since the expansion took effect
- State: Illinois still has no statewide ADU law. Gov. Pritzker's BUILD package (SB 4071 / HB 5626), which would have required every municipality to allow ADUs by right from Jan. 1, 2027, did not advance before the spring session ended June 1, 2026; Chicago's rules remain entirely local
- Pending: O2026-0026329 (Ald. Martin, introduced June 17, 2026, in the Zoning Committee) would let RS3 lots inside ADU-Allowed RS Areas use the reduced lot-area exemption to build a two-flat; it does not change the ADU standards above
Tips for Building an ADU in Chicago
- Start at the eligibility map on chicago.gov/adu. It tells you whether your lot is RT/RM/B/C (by right citywide), inside one of the ten ADU-Allowed RS Areas, and which of the three RS limitations apply: an annual block cap, owner-occupancy proof, or a $500 administrative adjustment with 10-day written notice to abutting owners and the alderperson (17-13-0107-A). An RS lot outside every area cannot be pre-certified; only an ordinance sponsored by your alderperson adding at least a block face and its opposite face (17-7-0575) changes that
- Size a coach house from the lot, not from a square-footage table: with the 700-square-foot cap gone, the building is set by 22 ft of height, the 15 ft gap behind the house (10 ft by adjustment on lots under 125 ft deep), the 3 ft open strip on one side, 2 ft off an alley and the rule that accessory buildings cover no more than 60% of the required rear setback. Two stories over a garage is the common form; ask your architect to run the 60% calculation from your district's required rear setback (17-2-0306) before you buy plans
- Cost basis: two Chicago design-build guides (January and March 2026) put a new coach house at $150,000-$350,000, typically $175,000-$250,000 for 450-600 sq ft, at $200-$400 per sq ft; converting an existing garage runs $150-$300 per sq ft and a basement or attic conversion $65,000-$150,000; a prefab coach house shell is quoted at $125,000-$200,000 before foundation and utilities ($15,000-$40,000 for separate meters). Construction values declared on 2025-26 coach-house permits (City data) had a median of $150,000, which excludes design and permit costs
- Plan for the affordability covenant before you add a second ADU: with two or more, half (rounded down) must rent at or below the 60% AMI limits ($1,367 for a one-bedroom, $1,641 for a two-bedroom in 2026, landlord paying utilities), be registered with DOH for $500 each, carry a recorded covenant with the Cook County Clerk and file an affidavit every year for 30 years. Many owners of 2-4 flats add exactly one unit for that reason
- Choose a coach-house builder by apprenticeship status first: DOH will not pre-certify a coach house unless the general contractor and every subcontractor are in a U.S. Department of Labor Registered Apprenticeship Program, so ask each bidder which program they and their electrical, plumbing and carpentry subs are registered in before you sign. Conversion units have no such rule
- A conversion unit is a Standard Plan Review or Self-Cert job with an Illinois-licensed architect, not an Express Permit; if you are 65 or older, have owned and lived in your 1-3 unit building for ten years and earn 80% of area median income or less, DOB must waive the permit and zoning fees for the alteration (14A-4-412.5.1). A new coach house does not qualify for the waiver
- An existing coach house that was lawfully established does not need a new pre-certification to be repaired, remodeled or extended (DOH requirements page), and a coach house built before May 1, 2021 is outside the short-term-rental ban; every newer ADU may only be rented on an ordinary residential lease, with fines of $1,500-$3,000 per day for offering it as a vacation rental or shared-housing stay
- Cost basis (2026-09-20 re-verification): short term allowed: No. A conversion unit, or a coach house established after May 1, 2021, may not be rented, leased or offered for transient occupancy as defined in Sec. 4-6-290 (vacation-rental and shared-housing stays) to anyone outside the household; each day is a separate offense with a $1,500-$3,000 fine (17-9-0131(8), 17-9-0201-F(17)). DOH: no short-term leases or vacation rentals such as Airbnb in any ADU. Ordinary residential leases are fine | roi estimate: 8-12% gross rental yield on a $175,000-$300,000 coach house renting at $1,600-$2,200/mo, before taxes, vacancy, insurance and financing; a $65,000-$150,000 basement conversion renting at $1,400-$1,900/mo returns 12-25% gross. An affordable-restricted ADU is capped at $1,367 (1BR) or $1,641 (2BR) gross rent in 2026
ADU Builders in Chicago
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Sources & References
All data on this page is sourced from official government records and verified market data. View our full methodology.
- Substitute Ordinance SO2024-0008918 as passed Sept. 25, 2025 (effective April 1, 2026): 2-44-065(10), 2-44-106, 17-2-0207, 17-2-0303-C, 17-3-0207, 17-3-0309, 17-7-0570 to 0575, 17-9-0131, 17-9-0201-C, -E, -F, 17-13-0107-A, 17-13-1003-OO/PP/QQ, 17-17-0309 | Chicago City Clerk eLMS Municipal Code — Accessed 2026-09-20
- SO2026-0022453 as passed Feb. 18, 2026 (effective April 1, 2026): Sec. 17-7-0574 ADU-Allowed RS Areas table, ten zones with limitations | Chicago City Clerk eLMS Municipal Code — Accessed 2026-09-20
- SO2025-0020513 as passed Dec. 10, 2025: first replacement of the 17-7-0574 table (twelve zones, superseded Feb. 2026) | Chicago City Clerk eLMS Municipal Code — Accessed 2026-09-20
- SO2020-2850 ADU pilot ordinance, passed Dec. 16, 2020: 17-9-0201-F(4)-(7) coach house parking, 22 ft height, rooftop features, 3 ft side open space (unchanged since) | Chicago City Clerk eLMS Municipal Code — Accessed 2026-09-20
- O2021-1228, passed April 21, 2021: 17-9-0201-D (60% of required rear setback for all accessory buildings), 17-2-0309-A side setbacks limited to principal residential buildings, 17-17-0309 coach house encroachment row and 2 ft alley setback | Chicago City Clerk eLMS Municipal Code — Accessed 2026-09-20
- Additional Dwelling Units Ordinance: Requirements (RS area limitations, owner-occupancy proof, $500 administrative adjustment, conversion-unit and coach-house counts, labor requirement) | Chicago Department of Housing Planning Department — Accessed 2026-09-20
- ADU Allowance by Zoning District chart (RS, RT, RM, B1-B3, C1-C2) | Chicago Department of Housing Planning Department — Accessed 2026-09-20
- Additional Dwelling Units Ordinance: Eligibility and interactive eligibility map | Chicago Department of Housing Planning Department — Accessed 2026-09-20
- Mayor Johnson, Ald. Lawson Celebrate Launch of ADU Expansion Ordinance, April 1, 2026 (320,000 parcels, 34 wards, follow-on ordinances) | City of Chicago Planning Department — Accessed 2026-09-20
- Additional Dwelling Units Ordinance: How to Apply for an ADU (pre-certification portal, alderperson notice, DOB permit) | Chicago Department of Housing Planning Department — Accessed 2026-09-20
- Additional Dwelling Units Ordinance: Affordability ($500 registration, covenant, 60% AMI) and Resources (no plan sets) | Chicago Department of Housing Planning Department — Accessed 2026-09-20
- 2026 Amended Building Permit Fee Tables, effective Jan. 6, 2026 (Tables 14A-12-1204.3(1), (3), (4): construction factors, $2,450 and $1,800 minimums) | Chicago Department of Buildings Planning Department — Accessed 2026-09-20
- Chicago Construction Codes permit fee excerpts: 14A-4-412.2.2.1 fee formula, 14A-4-412.3 additional fees, 14A-4-412.5.1 senior waiver, Table 14A-12-1204.1 deposit | Chicago Department of Buildings Planning Department — Accessed 2026-09-20
- Standard Plan Review Permit Program and Self-Certified Permit Application Program (zoning approval first; self-cert issues in about 10 business days) | Chicago Department of Buildings Planning Department — Accessed 2026-09-20
- Open Space Impact Fee worksheet, Jan. 1-Dec. 31, 2026 ($522 per unit under 800 sq ft) and 2024 substitute ordinance amending 16-18-040 | Chicago Department of Planning and Development Planning Department — Accessed 2026-09-20
- Building Permits dataset (ydr8-5enu): processing days, fees paid and reported cost for permits describing a coach house, conversion unit or ADU, issued Jan. 2025-Sept. 2026 | Chicago Data Portal Government Data — Accessed 2026-09-20
- Chicago Coach House Conversion Cost 2026 ($150K-$350K coach house, $200-$400/sq ft, prefab $125K-$200K, utilities $15K-$40K), Jan. 4, 2026 | Assembly Service IL (industry) industry — Accessed 2026-09-20
- Chicago ADU Rules for Homeowners 2026 (coach house $150K-$350K+, basement conversion $65K-$120K+, $130-$250/sq ft), March 26, 2026 | Bofran Builders (industry) industry — Accessed 2026-09-20
- Convert Your Garage to a Legal Coach House with the 2026 Chicago ADU Ordinance ($200-$400/sq ft) | Arete Renovators (industry) industry — Accessed 2026-09-20
- 2026 Income and Rent Limits, effective May 1 / June 1, 2026: 60% AMI gross rents $1,367 (1BR) and $1,641 (2BR); HUD Fair Market Rents $1,581 and $1,781 | Chicago Department of Housing Government Data — Accessed 2026-09-20
- FY2026 Fair Market Rents, Chicago-Joliet-Naperville, IL HUD Metro FMR Area: 0BR $1,480, 1BR $1,581, 2BR $1,781, 3BR $2,294 | HUD User Government Data — Accessed 2026-09-20
- Chicago, IL rent research, September 2026: median 1BR $2,195, 2BR $2,535; Rogers Park $1,600 to Near North Side $2,903 | Zumper (market data) Market Data — Accessed 2026-09-20
- Chicago ADU Portal (background, Sec. 2-44-106, process, ADU@cityofchicago.org) | Chicago Department of Housing Planning Department — Accessed 2026-09-20
- Despite BUILD's failure, housing advocates celebrate legislative wins, June 12, 2026 (BUILD package with statewide ADU mandate did not advance by June 1) | Capitol News Illinois News Source — Accessed 2026-09-20
- City Clerk eLMS records SO2024-0008918, SO2025-0020513, SO2026-0022453 (votes, dates) and O2026-0026329 (pending) | Chicago City Clerk Government Data — Accessed 2026-09-20
Frequently Asked Questions
Can I build an ADU in Chicago?
Yes. ADUs are allowed in By right in every RT (two-flat, townhouse and multi-unit) and RM (multi-unit) district citywide and in the B1, B2, B3, C1 and C2 business and commercial districts (use tables 17-2-0207 rows 7-8 and 17-3-0207 rows 5-6). In RS1, RS2 and RS3 single-family districts only on lots inside one of the ten ADU-Allowed RS Areas defined in Sec. 17-7-0574 (as replaced by SO2026-0022453, effective April 1, 2026), which the City says cover parts of 34 of the 50 wards; an RS lot outside those areas cannot get a permit (17-9-0131(1), 17-9-0201-F(1)). Shown as not allowed in C3, and the ordinance did not amend the use tables of the downtown D or manufacturing districts. In B and C districts a coach house must sit in the rear 30 ft of the lot, and a conversion unit below the second floor is by right only if 40% of the ground-floor frontage stays commercial (B2 excepted); otherwise it needs Zoning Board of Appeals approval under 17-9-0131(7) in Chicago. The maximum size for a detached ADU is any size that fits the coach house bulk rules; Chicago sets no floor-area cap since the pilot's seven-hundred-square-foot dwelling-unit limit was repealed with the citywide ordinance (effective April 1; see recent changes). What sizes the building: 22 ft height limit, one dwelling unit per coach house, a 15 ft gap behind the main house, the rule that all accessory buildings together may cover no more than 60% of the required rear setback area, and a 3 ft open strip along one side. Coach houses are exempt from floor-area-ratio, lot-area-per-unit and rear-yard open-space minimums but may not eat into open space the main building needs. Owner-occupancy: Depends on the zone. Not required on RT, RM, B or C lots or in ADU-Allowed RS Areas 1, 6 and 7. Required at pre-certification when the main building is a detached house in RS Areas 2, 3, 4, 5, 8, 9 and 10 (17-7-0573(2), 17-7-0574): DOH asks for a government photo ID plus a tax bill, utility bill, deed, mortgage statement or insurance declaration for the address. Nothing in the ordinance requires owner-occupancy after the permit issues.
How much does an ADU cost in Chicago?
ADU construction in Chicago typically costs $150,000-$350,000. Garage conversions run $75,000-$200,000, and prefab ADUs cost $125,000-$250,000.
How much can I rent an ADU for in Chicago?
Average ADU rents in Chicago are $1,500-$2,200/mo for a 1-bedroom and $1,800-$2,600/mo for a 2-bedroom unit.
Do I need parking for an ADU in Chicago?
None required for a conversion unit or a coach house (17-9-0131(5), 17-9-0201-F(4)). Parking the main building must keep may be reduced or waived by administrative adjustment when a coach house is built (17-9-0201-F(3), 17-13-1003-OO), so a garage can become the coach house's ground floor or be removed. Check with Chicago planning department for the latest Illinois ADU parking rules, as many states have relaxed requirements in recent years.
How long does it take to get an ADU permit in Chicago?
Chicago does not publish a standard ADU review timeline. City permit records (Chicago Data Portal, permits issued January-September 2026 for a coach house, conversion unit or ADU) show Standard Plan Review permits issuing a median 120 days after the application date (middle half 78-183 days) and Self-Certification permits a median 58 days (35-98 days); DOB says self-certified applications typically issue within 10 business days after zoning approval. Add the DOH pre-certification review before either. Fees range from $2,525-$3,050 for a new coach house in 2026 permit records (DOB building permit fee minimum $2,450 for new residential construction in Table 14A-12-1204.3(3), plus a $75 zoning review fee on most permits; a few paid $1,500 zoning fees). $1,875-$3,150 for a conversion unit (minimum $1,800 for a permit that adds a dwelling unit, Table 14A-12-1204.3(4), plus zoning). The formula is construction factor x review factor x floor area (14A-4-412.2.2.1; $0.44 per sq ft x 0.75 for a wood-frame Group R coach house), so the minimums govern any ADU-sized project. A $300 deposit is paid at application (14A-12-1204.1). DOH lists no pre-certification fee; an affordable ADU costs $500 to register.
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