Building permits in Cook County, Illinois
Find the right authority before you build. Cook County permitting follows Illinois law — here is exactly who issues the permit and where to start.
County + cities (mixed)
Cook County Department of Building & Zoning (unincorporated areas); City of Chicago issues its own permits
The Cook County Department of Building & Zoning issues building permits only for unincorporated Cook County. The City of Chicago and all other incorporated municipalities (suburban cities and villages) issue their own permits; the county does not process permits for properties inside incorporated boundaries.
Permit cheat-sheet (Illinois rules)
| Project | Permit? | Authority | Typical fee | Timeline | Go / No-Go | Key notes |
|---|---|---|---|---|---|---|
| 🏠 Accessory Dwelling Unit (ADU) | Permit required | city | No flat statewide fee; Chicago calculates fees from construction type, occupancy, square footage, and scope via its online calculator. Other municipalities set their own fees. | — | Case by case | Illinois has no statewide building code; most municipalities use the IRC while Chicago enforces the 2019 Chicago Building Code. ADUs require a building permit plus local zoning approval — Chicago and other cities regulate ADUs through zoning. Verify with your municipality. |
| 🪵 Deck / Porch | Permit required | city | Chicago fees via online calculator; other municipalities set their own. | — | Generally allowed | Decks and porches require a permit (Chicago requires permits for decks/porches). Chicago offers an Express Permit for eligible deck work; most other IL towns follow IRC R105. |
| 🧱 Fence / Wall | Conditional | city | — | — | Generally allowed | Chicago requires a permit for fences (handled via the Express Permit Program). Other Illinois municipalities often exempt fences at or below 6 ft. Verify locally. |
| 🛖 Shed / Outbuilding | Conditional | city | — | — | Generally allowed | Larger sheds and any shed with utilities require a permit. Confirm the threshold with your local building department. Exempt: Under ~120 sq ft typically exempt under the IRC; varies by municipality. |
| 🪜 Basement Finish | Permit required | city | Municipal building permit fee; varies with scope. | — | Generally allowed | Finishing a basement into habitable space requires permits for egress, framing, electrical, plumbing, and mechanical work. Sleeping rooms need code-compliant egress. |
| 🚗 Garage / Carport | Permit required | city | Municipal building permit fee. | — | Generally allowed | A new garage requires a permit. Chicago’s Easy/Express Permit covers private (detached frame) garages; elsewhere a standard building permit applies. |
| ☀️ Rooftop Solar PV | Permit required | city | Electrical/structural permit fee set by municipality. | — | Generally allowed | Rooftop solar PV requires an electrical and structural permit. Chicago’s Express Permit covers small-scale residential solar PV; other municipalities issue a solar/electrical permit. |
| 🌡️ HVAC Replacement | Permit required | city | Mechanical permit fee set by municipality. | — | Generally allowed | Furnace, AC, or heat-pump replacement requires a mechanical (HVAC) permit and inspection. Chicago requires a city-licensed mechanical contractor. |
| 🍳 Kitchen Remodel | Permit required | city | Building permit fee; trade permits billed separately. | — | Generally allowed | A permit is required when relocating plumbing/electrical, moving walls, or changing fixtures. Cosmetic-only work may be exempt. |
| 🛁 Bathroom Remodel | Permit required | city | Building permit fee; trade permits billed separately. | — | Generally allowed | A permit is required when relocating plumbing/electrical, moving walls, or changing fixtures. Cosmetic-only updates may be exempt. |
| 🏗️ Room Addition | Permit required | city | Building permit fee based on valuation; zoning and plan review apply. | — | Generally allowed | Room additions change the footprint and require a full building permit and zoning approval. Chicago uses the 2019 Chicago Building Code for plan review. |
| 🪟 Window / Door Replacement | Conditional | city | — | — | Generally allowed | Swapping windows or exterior doors in the same opening is usually permitted via an expedited process; enlarging openings requires a full permit. |
| 🏘️ Roof Replacement | Permit required | city | Roof-covering permit fee set by municipality. | — | Generally allowed | Re-roofing is covered by Chicago’s Express Permit; elsewhere a roofing permit is required. Minor repairs may be exempt. |
| 🅿️ Driveway / Parking Pad | Conditional | city | — | — | Generally allowed | A permit may be required where the driveway connects to the street/right-of-way or triggers an excavation/erosion permit. Verify locally. |
| 🏊 Swimming Pool / Spa | Permit required | city | Building permit fee; barrier fencing required by code. | — | Generally allowed | Pools require a permit and barrier. Chicago processes pools via its Express/specialty permit programs; other municipalities issue a standard permit. |
| 🧱 Retaining Wall | Conditional | city | — | — | Generally allowed | Height and whether the wall supports a surcharge (driveway, structure, or slope above) determine the permit threshold. Verify with your municipality. |
Sources: Cook County Department of Building & Zoning — Building Permits · ICC — Illinois Codes (no statewide code; local adoption) · Illinois Capital Development Board — Building Codes · City of Chicago — Guide to Building Permits (2019 Chicago Building Code) · City of Chicago Dept. of Buildings — Permits