An ADU builder in Chicago is a licensed contractor who designs and constructs accessory dwelling units — detached backyard units, garage conversions, attached additions, and junior ADUs (JADUs). Because an ADU is a complete second dwelling, the builder coordinates foundation, framing, plumbing, electrical, and HVAC work and pulls it through Chicago's permit process and utility connections. Not every general contractor has built one, so the right builder is one with ADU-specific experience in Illinois.
What ADU Builders Cost in Chicago [17][18][19]
Based on our Chicago cost data, expect the following ranges from local ADU builders. Quotes for the same scope typically vary 20-40% between contractors, so getting at least three bids is the single best way to control cost.
| New Detached ADU (all-in) | $150,000-$350,000 |
| Cost per Sq Ft | $200-$400 |
| Garage Conversion | $75,000-$200,000 |
| Prefab / Modular ADU (installed) | $125,000-$250,000 |
| City Permit & Plan Review | $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 |
For a full line-item breakdown, see our Chicago ADU cost guide. To confirm what you're allowed to build before you hire, review the Chicago ADU rules (max detached size: 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).
Get Free ADU Quotes in Chicago
Tell us about your project and we'll pass it to ADU builders serving Chicago. Free, no obligation — you choose who to work with. We don't have builders in every area yet; if nobody covers yours, we'll email you to say so.
1. Tell us your project
Takes about a minute.
Takes about a minute.
2. We match local pros
Up to 5 independent local ADU builders — never more, and we tell them nothing you don't submit here.
Up to 5 independent local ADU builders — never more, and we tell them nothing you don't submit here.
3. You choose
Compare quotes, verify license & insurance, hire (or don't). No spam either way.
Compare quotes, verify license & insurance, hire (or don't). No spam either way.
🔒 Your info is secure. We share it only with contractors quoting your project. No spam, no obligation.
Just browsing? Search ADU builders near you by ZIP code.
How to Vet an ADU Builder in Chicago
- License: Confirm a current contractor's license in Illinois and that it's in good standing. Ask for the license number and verify it with the state board.
- ADU-specific experience: Ask how many ADUs they've completed in or near Chicago and request addresses or photos. ADU permitting and setbacks differ from a kitchen remodel.
- Portfolio & references: Get references from recent ADU clients and, if possible, visit a finished unit.
- Insurance: Verify general liability and workers' compensation coverage. Ask for a certificate of insurance.
- Written, detailed bid: Insist on an itemized, fixed-price or clearly-scoped bid — not a verbal estimate. It should state whether permits ($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), 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), and 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) are included.
- Permit handling: Confirm they manage Chicago's permit 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", typically 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) and who is responsible if revisions are required.
- Payment schedule: Avoid large upfront payments. A reasonable schedule ties payments to completed milestones.
Questions to Ask Before You Hire
- How many ADUs have you built in Chicago in the last two years?
- Is your bid fixed-price, and what would trigger a change order?
- Are permits, plan check, and utility connection fees included?
- What's a realistic timeline, including permit review (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) and construction?
- Who is my point of contact and how are delays communicated?
- What warranty do you provide on workmanship?
- Can you share three recent Illinois ADU client references?
Finance Your ADU Project
Most ADU projects are funded through HELOCs, construction loans, or cash-out refinancing. Compare rates from top lenders.
Some links on this page are affiliate links. We may earn a commission at no extra cost to you. Learn more
Are you an ADU builder? Get Chicago leads
Homeowners on this page submit real ADU project requests in Chicago. Each one goes to up to five local builders — that is what the homeowner agrees to — so claiming never takes it from anyone and there is no bidding. In practice far fewer ever make contact, which is why the number is five rather than three. A flat $50 only on the leads you accept: no subscription, no contract, and you deal with the homeowner directly.
Get Chicago ADU Leads →Frequently Asked Questions
How much do ADU builders charge in Chicago?
ADU builders in Chicago typically quote $150,000-$350,000 for a new detached unit, or about $200-$400 per square foot, including design, permitting, and construction. A garage conversion runs $75,000-$200,000 and a prefab/modular ADU averages $125,000-$250,000. Add city permit and plan-review 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) plus impact fees of $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. Quotes for the same scope commonly vary 20-40% between builders, so collect at least three bids.
How do I find a good ADU builder in Chicago?
Look for a licensed contractor with completed ADU projects in Chicago specifically — ADUs involve local zoning, setback rules, and utility connections that general remodelers may not have handled. Verify the license, ask for an ADU-specific portfolio and references, confirm they carry liability and workers' comp insurance, and get a written fixed-price or detailed bid. Submit a request below and we'll forward it to local ADU builders serving Chicago for free quotes.
Do ADU builders in Chicago handle permits?
Most full-service ADU builders manage the permit process for you. In Chicago the approval process is "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 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. Confirm in writing whether permit fees, 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), and impact fees are included in the bid or billed separately.
How long does it take to build an ADU in Chicago?
Plan for the permit review (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 in Chicago) plus construction. Most detached ADUs take 4-8 months of construction after permits are issued; garage conversions and prefab units are often faster. Ask each builder for a realistic schedule and what could delay it.
Get Free ADU Builder Quotes in Chicago
Compare bids from experienced local Chicago ADU builders. Free, no obligation.
Get Free Quotes →