State building permit guide
Illinois building permits — complete guide (2026)
Illinois permitting is dominated by the Chicago metro, which has its own unique building code and permitting system. Suburban Cook County and downstate Illinois have significantly simpler, faster requirements.
Avg cost: $200–$800
Processing: 2–8 weeks
~55,000 permits/year
102 counties
$200–$800Average permit cost
2–8 weeksProcessing time
~55,000Permits issued/year
No — Chicago is restrictiveADU-friendly
Chicago has its own building code — the Chicago Building Code — which differs significantly from the International Building Code used by the rest of Illinois. Chicago permits often require licensed architects and engineers to file applications. Suburban and downstate Illinois permits are much more straightforward and affordable.
Permit costs by type — Illinois
| Permit type | Fee range | Processing time | Notes |
|---|---|---|---|
| Electrical | $120–$350 | 2–7 days | Chicago: licensed electrician must pull permit |
| Plumbing | $100–$300 | 2–7 days | Chicago: licensed plumber required |
| HVAC / Mechanical | $120–$350 | 2–7 days | Chicago: licensed mechanical contractor |
| Roofing | $150–$450 | 2–7 days | Chicago: licensed roofing contractor required |
| Room Addition | $500–$1,500 | 4–10 weeks | Chicago: architect required for most additions |
| New Construction | $1,000–$3,500 | 4–12 weeks | Chicago: extensive plan review process |
| Garage Conversion | $300–$800 | 2–6 weeks | Suburban IL — simpler process |
| Deck / Patio | $150–$500 | 2–5 weeks | Frost-line footings required (42 inches) |
| Fence | $75–$200 | 1–5 days | HOA rules common in suburban IL |
| Solar | $120–$350 | 2–7 days | Illinois Future Energy Jobs Act supports solar |
How to get a building permit in Illinois
1
Determine Chicago vs. suburban or downstate process
If you are in Chicago city limits, all permits go through the City of Chicago Department of Buildings. The process differs significantly from suburban Cook County, DuPage, Lake, and other collar counties.
2
Chicago: access the city permit portal
Chicago's permit portal handles most applications. Simple work permits can be obtained online. Complex projects require a licensed design professional to file.
3
Chicago: understand trade license requirements
Chicago requires licensed contractors to pull permits for all electrical, plumbing, HVAC, and roofing work. Homeowners cannot self-perform permitted trade work in Chicago.
4
Suburban and downstate: contact your local building department
Outside Chicago, permits are handled by city or village building departments. Many suburbs have streamlined systems with shorter timelines and lower fees than Chicago.
5
Inspections
Chicago has a dedicated inspection division with online scheduling. Wait times can be significant during busy seasons. Suburban municipalities generally have faster turnaround.
Permit costs by county — top Illinois counties
Cook (Chicago) County
$300–$1,500
4–12 weeks
Cook (suburban) County
$200–$650
2–6 weeks
DuPage (Naperville) County
$175–$550
2–5 weeks
Lake (Waukegan) County
$175–$550
2–5 weeks
Will (Joliet) County
$150–$450
2–5 weeks
Kane (Aurora) County
$150–$450
2–4 weeks
Winnebago (Rockford) County
$125–$375
1–4 weeks
Sangamon (Springfield) County
$125–$375
1–4 weeks
Frequently asked questions — Illinois permits
Why does Chicago have its own building code?
Chicago adopted its own building code in the 1800s and has maintained it independently ever since. It is one of the few major US cities not using the International Building Code, making it unique in the country.
Can I do my own electrical work in Chicago?
No. Chicago requires a licensed electrical contractor to pull and perform all permitted electrical work. Homeowners cannot self-perform electrical work in the City of Chicago.
How is permitting different in suburban Illinois vs. Chicago?
Suburban Illinois cities use the IBC/IRC and generally allow homeowners more flexibility, faster processing, and lower fees than Chicago. Many suburban municipalities allow owner-builders.
Does Illinois have an ADU law?
Illinois does not have a statewide ADU law. Chicago has historically been restrictive on ADUs. Suburban municipalities vary widely — check your local zoning ordinance.
Data sources: US Census Bureau BPS 2024 · Illinois Illinois Department of Commerce and Economic Opportunity · Shovels.ai permit aggregator