Cook County is the most populous county in Illinois and the second-most populous in the United States at about 5.2 million residents, home to Chicago and more than 130 other municipalities. Its Department of Building and Zoning permits and inspects only the unincorporated areas of the county and the Forest Preserves; the vast majority of Cook County residents live inside a municipality that runs its own department.
This guide covers the county’s unincorporated-area role, its own contractor registration, the Cook County code, and where municipal work goes instead.
This guide covers unincorporated Cook County. Chicago and the other municipalities each run their own permitting.
The first question in Cook County is whether the parcel is unincorporated or inside a municipality. The Department of Building and Zoning is the authority only for unincorporated areas and the Forest Preserves; work inside Chicago or any other city or village files with that municipality. Contractors must register with Cook County — a registration distinct from the City of Chicago’s — before pulling a county permit.
What requires a building permit in Cook County?
Permit required
- New commercial, multi-family and residential construction, additions and change of occupancy
- Structural alterations, load-bearing changes, foundations, decks and retaining walls
- Electrical work — services, panels, circuits, solar and EV charging — under the adopted electrical code
- Plumbing under the statewide Illinois Plumbing Code, tied to a licensed plumber
- Mechanical and HVAC change-outs, and work affecting the energy envelope
- Re-roofing above the exempt scope, pools, signs, and demolition
Often exempt
- Minor repairs and maintenance replacing materials in kind
- Small accessory structures below the local threshold, where zoning allows
- Painting, flooring, cabinetry and other finish work
- Like-for-like fixture or appliance swaps with no alteration to wiring or piping
Because the code edition and its amendments are set locally, the exempt list and thresholds differ from one jurisdiction to the next — a project waved through in one town needs a full permit set in the next. An exemption from a building permit is never an exemption from zoning, the statewide energy or plumbing codes, or an electrical or plumbing permit. Confirm scope with the Department of Building and Zoning before work starts.
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Get a free quote →The statewide layers that apply everywhere
Three Illinois codes apply statewide: the Illinois Energy Conservation Code, which applies even where a town does not actively enforce it; the Illinois Plumbing Code, from the Department of Public Health, which also licenses plumbers (a local government may adopt a stricter plumbing code, and Chicago has its own plumbing and energy codes and licenses its own plumbers); and the Illinois Accessibility Code. In unincorporated Cook County, the Department of Building and Zoning administers the Cook County building code and requires its own contractor registration; septic-served projects also need Cook County Department of Public Health approval.
Illinois leaves building codes to local government, but since 1 January 2025 any local code must regulate structural design at least as strictly as baseline editions of the International Building, Existing Building and Residential Codes, and where no code was adopted the statute sets minimums for commercial buildings and new homes (Public Act 103-0510). Illinois codes and the statewide baseline
Who handles permitting in Cook County?
The Department of Building and Zoning handles permitting and inspections only for unincorporated Cook County and the Forest Preserves; municipalities handle their own. Its offices are the George W. Dunne Cook County Office Building, 69 West Washington Street, Chicago, IL 60602 (312-603-0500), with a satellite office at 5600 Old Orchard Road, Suite 155, Skokie (847-470-3730); both are open Monday to Friday 8:30am to 4:30pm.
| Detail | Information |
|---|---|
| Authority | Cook County Department of Building and Zoning |
| Serves | Unincorporated Cook County and the Forest Preserves |
| Phone | 312-603-0500 |
| Registration | County contractor registration required (separate from Chicago) |
| Septic | Cook County Department of Public Health approval where applicable |
| Code | Cook County building code, plus statewide Illinois codes |
| Filing | Applications by email to intake.bnz@cookcountyil.gov (online e-permits for listed simple jobs); invoices payable online |
| Municipal work | Handled by the city or village, not the county |
The Department of Building and Zoning is the authority for unincorporated Cook County and the Forest Preserves. Applications go by email to the intake desk, with a deposit of $100 (residential) or $500 (non-residential); simple jobs such as decks, fences, re-roofs, sheds and window replacement can be filed as online e-permits. Contractors register with the county — explicitly not the City of Chicago — and each contractor submits a letter of intent. On septic-served sites, Cook County Department of Public Health approval is required at submission.
Not sure this scope needs a permit?
Get a free quote →Because most of Cook County is incorporated, confirm the jurisdiction from the parcel first; a project inside a municipality files with that city or village, each of which runs its own code and counter.
Permit types
Residential permits
Unincorporated residential work is permitted and inspected by the county under the Cook County code. Re-roofs, decks, solar and EV chargers need permits, plumbing is tied to a state-licensed plumber, and contractors must hold current county registration before pulling a permit.
Commercial permits
Commercial and multi-family work in unincorporated areas is a county matter; buildings with more than four residential units must also be registered with the department each year (a rule adopted in 2015). All of it requires county-registered contractors, state-licensed plumbing, and compliance with the statewide energy and accessibility codes.
Registration, trade licences and design professionals
Practically, three credential layers appear on Illinois projects: local contractor registration with the Department of Building and Zoning; state licences for plumbing and roofing; and, on commercial and larger residential work, drawings from an Illinois-licensed design professional. Confirm what the Department of Building and Zoning requires for the specific building before filing.
Illinois licenses plumbers through the Department of Public Health and roofing contractors through the Department of Financial and Professional Regulation; there is no state general contractor or electrician licence, and many jurisdictions require local registration. Contractor credentials in Illinois
Cook County permit costs and fees
Budget the county building permit fee, separate electrical and plumbing permits, county contractor registration ($150 per trade, then $75 a year), and any Public Health septic review. Under the schedule in force since December 2020, new construction is charged by building volume ($37.50 per 1,000 cubic feet up to 50,000 cubic feet) and alterations by estimated cost (a $73.50 minimum plus $18.50 per $1,000 above $5,000); the invoice is posted to your online profile.
Rather talk it over?
Call 1-855-478-4290 →| Fee component | How it works |
|---|---|
| Building permit | Based on project valuation or square footage; set by the local schedule |
| Plan review | A percentage of the permit fee or a flat charge, at submittal |
| Trade permits | Separate electrical, plumbing and mechanical fees |
| Contractor registration | Local registration fees for the trades pulling permits |
| Zoning and impact | Local zoning review, and impact or capital fees in growth areas |
| Re-inspections and revisions | Additional fees for failed inspections, revisions and expired permits |
Illinois sets one useful certainty in law: once a permit is issued, the code requirements in effect on January 1 of the year you applied govern for the life of that permit, so a mid-project code change will not move the target. Fee schedules, though, are local and change, so a figure from a neighbouring town is not reliable — ask the Department of Building and Zoning for the schedule in force on your filing date.
Need a real number for a specific Cook County project? Send us the scope, address and valuation and we will identify the authority having jurisdiction, the code edition in force and the fee categories that will apply.
Trade permits and who may pull them
Permit required
- Service installations, panel upgrades, new circuits, solar PV and EV chargers
- New plumbing, repipes, water heater change-outs, fixtures, backflow and gas piping
- HVAC installation and change-out, ductwork, venting and commercial kitchen exhaust
- Sprinkler, standpipe and fire alarm work on commercial and multi-family structures
Typically exempt
- Replacing a fixture, switch, receptacle or light with no alteration to wiring or piping
- Clearing a stoppage without replacing or rearranging concealed piping
- Filter, thermostat and routine component service
- Like-for-like appliance repair that does not alter the connection
Plumbing follows the Illinois Plumbing Code and a licensed plumber (Chicago licenses its own plumbers); electrical and mechanical work follow the locally adopted codes and local licensing or registration. Trade credentials in Illinois
Rather not deal with the Cook County building department?
Get a free quote →How to apply for a Cook County building permit
Only unincorporated Cook and the Forest Preserves file with the county.
County registration is separate from the City of Chicago’s.
Septic-served sites need Public Health approval at submission.
Plumbing and roofing are state-licensed; other trades register locally.
Each trade submits a signed letter of intent.
Email the application to intake.bnz@cookcountyil.gov (or use an e-permit for simple jobs); the fee invoice can be paid online.
Review, corrections and what actually causes delay
In Illinois, the first cause of delay is uncertainty over jurisdiction and the applicable code edition — filing under the wrong amendments, or with the county when a municipality should have it. After that come missing local contractor registrations, a plumbing scope not tied to a state-licensed plumber, energy-code documentation, and a submittal that did not match what the Department of Building and Zoning requires. Build the review time into the schedule and confirm the checklist before filing.
A building permit carries a validity period set by Cook County; confirm the expiry on phased or delayed work before it passes. Permit validity in Illinois
Inspections in Cook County
Where a permit is required, standard checkpoints include footing and foundation, framing, rough-in electrical, plumbing and mechanical, insulation and energy, fire systems on commercial work, and final, with a certificate of occupancy before use. On issuance the county provides the field inspectors and the construction stages that must be inspected.
Illinois is tightening inspector qualifications: from January 1, 2027, those who perform building inspections must hold International Code Council certification, with a grace period after hire. Confirm the notice the Department of Building and Zoning needs and schedule around its inspection windows.
Want this handled start to finish?
Get a free quote →Do not cover work before the required inspection has been approved. Keep the issued permit, the approved plans, product listings, energy documentation and your correction responses available on site.
Cook County permit search and official resources
Permit records in Illinois sit with the local authority that issued them. Where the Cook County Department of Building and Zoning is the authority for unincorporated Cook County, it holds the building permit, the inspection history and the certificate of occupancy. If you are buying, refinancing or renovating, confirm that past work was permitted rather than assuming it was — and confirm the code edition that was in force.
Confirm the authority having jurisdiction and the code edition first. Illinois’s local-adoption structure — with the statewide baseline now under it — means the applicable code and amendments vary by parcel. Confirm current requirements, fees and review turnaround for your filing date.
These are the primary sources behind this guide. Codes, fee schedules and procedures change — confirm the position for your filing date.
- Cook County Department of Building and Zoning
- Illinois Capital Development Board (statewide codes)
- Illinois Plumbing Code (IDPH)
- Illinois DFPR (roofing and professional licensing)
- Illinois Office of the State Fire Marshal
Frequently asked questions
Who issues building permits in Cook County?
The Department of Building and Zoning issues permits only for unincorporated Cook County and the Forest Preserves; Chicago and the other municipalities run their own departments.
Inspections are where schedules slip.
Get a free quote →Do I register with the county or with Chicago?
With Cook County. County contractor registration is explicitly separate from the City of Chicago’s; a county permit requires county registration.
How do I know if my parcel is unincorporated?
Confirm with the Department of Building and Zoning; most of Cook County is incorporated, so many parcels file with a municipality instead.
Does the county handle plumbing permits?
Yes. In unincorporated areas the county issues plumbing permits (filed with a supplemental plumbing application), reviews plumbing and requires plumbing contractors to register with it. The plumber must hold a State of Illinois or Chicago plumber licence.
Do I need septic approval?
On septic-served sites, yes — Cook County Department of Public Health approval is required at submission.
How do I run a Cook County permit search?
The Department of Building and Zoning holds permit and inspection records for unincorporated areas; municipal records sit with each city or village.
Simplify Cook County permitting with Alliance Permitting
Cook County turns on one threshold question — unincorporated or municipal — and then on county registration and the Cook County code. Getting that settled up front is most of the battle in the nation’s second-largest county.
Trusted by leading builders, developers, and national contractors — 21+ years of filing in the jurisdictions we write about.
Contractors and builders choose Alliance for Cook County because the work is done by people who have stood at the counter:
- We confirm whether the parcel is unincorporated or municipal.
- We register the trades with Cook County, separate from Chicago.
- We clear Public Health septic review where it applies.
- We confirm state plumbing and roofing licences.
- We file with the county intake desk, with letters of intent, and track issuance.
Alliance Permitting is a permit documentation and submission company in Illinois. We prepare your paperwork, file it correctly and coordinate with the permitting authority through issuance. We are not a contractor and we do not perform licensed plan review or inspections; that work stays with your licensed team and the jurisdiction.
Ready to break ground in Cook County sooner?
Let Alliance prepare, file, and track your Cook County permits while your crew stays on the job.
More Illinois permitting guides
This guide is provided by Alliance Permitting for general information about Cook County permitting. Requirements, fees, and procedures change; confirm details with the permitting authority before relying on them.