Who issues your permit
Suburban Cook County's 120 or so cities, villages and towns each issue their own permits and set their own shed size limits, so a garage in Tinley Park or Mount Prospect is permitted there. Only unincorporated land is permitted by the County's Department of Building and Zoning. Check which applies in CookViewer with the "Unincorporated Area" layer. The rules below are the County's.
What the County asks for
The County's building permits page says "All work in unincorporated Cook County, other than ordinary repairs" needs a permit, and its detached shed or garage checklist (for structures under 625 square feet, read 24 October 2026) lists:
- The application with your PIN and whether the house is on well and septic or water and sewer.
- Full construction details: stud size and spacing, rafter size and spacing, foundation and slab, roofing, ridge and header sizes. The floor must slope to a drain or toward the overhead door.
- A plat of survey by an Illinois registered surveyor, not more than five years old, showing well and septic if you have them.
- A site plan with the structure's distance from every lot line and from other buildings.
- Maximum height: 15 feet for detached residential accessory structures.
The wiring rule
The same checklist sets the electrical part, which covers gazebos too:
| Rule | What it means |
|---|---|
| Sheds or gazebos over 144 sq ft, and all detached garages, "require electric" | A small shed can be unwired; a garage cannot |
| At least one switch and light, and at least one receptacle, all GFCI | Garages also need a switched light near the service door |
| Fed from the residence; "NO SEPARATE METER ALLOWED" | The circuit runs underground from your panel |
| Inspection of the in-ground conduit before the trench is filled | Book it after the permit is issued and before backfill |
The wiring needs a letter of intent from a registered electrical contractor, signed by the supervising electrician, and floor plans showing every light, switch, receptacle and subpanel.
Who can pull it
Contractors register with Building and Zoning ($150 per trade, then $75 a year). A homeowner can build it, if registered (General registration is free), living in the house, insured for at least $1,000,000 of liability naming Cook County Building and Zoning, and listed on the permit (Contractor Registration). The electrical work still needs a registered electrical contractor.
What it costs
From the fee schedule amendment effective 1 December 2020:
| Fee | Amount |
|---|---|
| Private garages and sheds, building permit | $73.50 minimum |
| Electrical, single-family garage | $150.00 |
| Deposit at application (residential), credited to the fee | $100 |
| Permit extension (one allowed, six months) | 10% of the original fee, or $25 if greater |
What 6,035 suburban garage and shed permits show
From the Assessor's copy of the suburbs' permits (garages, sheds and shade structures):
| Measure | Suburban Cook County garages, sheds and shade structures |
|---|---|
| Permits issued, Jan 2024 to Dec 2025 | 6,035, about 3,018 a year |
| Last 12 months on file (Jan to Dec 2025) | 2,807, 13% fewer than the 3,228 the year before |
| Usual declared value | $4,689 (middle half $2,000 to $11,200) |
| Busiest month / quietest month | May (index 154) / February (33) |
| Filed as "Garage Carports Barns" | 3,704, 61% |
Another 15% were filed under the suburbs' "Driveways - Patios - Wood Deck" type. April through July run 37% to 54% above an average month. National garage figures are in detached garage cost; other cities' rules are in do I need a permit to build a garage and do I need a permit for a shed.
Checking the work
Permits already on your address are covered in Cook County building permit search, and Illinois licence lookups in how to check a contractor's license in Illinois. The year and month breakdown is on permit statistics, and individual rows on browse permits.
What this does not tell you
The Assessor's file holds only the permits a suburb reported, names no contractor, has no ZIP code we can publish and no final inspection dates. Garages of 625 square feet or more fall outside the County's short checklist, and village rules differ from the County's.
How we know this
The unincorporated rules are from Cook County Building and Zoning's detached shed or garage checklist, building permits page and Contractor Registration page, and fees from its fee schedule amendment effective 1 December 2020, all read 24 October 2026. Our counts are the Cook County Assessor's Assessor - Permits file, read 20 October 2026: suburban permits issued January 2024 to December 2025, Chicago excluded.
Numbers come from public permit records in 57 cities, data through October 20, 2026. Nobody paid to be on this page and nobody can.
Questions
- Do I need a permit for a shed in unincorporated Cook County?
Yes. The County says all work in unincorporated Cook County needs a permit apart from ordinary repairs, and it publishes a permit checklist for detached sheds and garages under 625 square feet. In a village, the village's building department decides.
- How tall can a shed or garage be in unincorporated Cook County?
15 feet. The County's checklist says the maximum height of detached residential accessory structures is 15 feet, and the plans must show the distance to every lot line and to other buildings.
- Does a detached garage need electricity in Cook County?
In unincorporated Cook County, yes: all detached garages, and sheds or gazebos over 144 square feet, require electric, with at least one switched light and one GFCI receptacle, fed from the house with no separate meter. A registered electrical contractor signs the letter of intent.
- How much is a garage permit in unincorporated Cook County?
The County's fee schedule (effective 1 December 2020) lists private garages and sheds at a $73.50 minimum; the electrical fee schedule lists $150 for a single-family garage. A $100 residential deposit is paid when you apply and credited to the fee.
- How many garage and shed permits do Cook County suburbs issue?
6,035 garage, shed and shade structure permits were reported to the Cook County Assessor from January 2024 to December 2025, with May the busiest month. The usual one declared $4,689.
Build your own list
Pick your city and the kind of work. Every firm with a permit on record, sorted by what you value.
Related guides
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- Do I need a plumbing permit in New Orleans? The master-plumber rule, the Sewerage and Water Board, and 7,492 permits
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- Detached Shed or Garage (less than 625 sq. ft.) Permit Requirements — Cook County Department of Building and Zoning (2026-10-24)
- Building and Zoning Building Permits — Cook County (2026-10-24)
- Building and Zoning Contractor Registration — Cook County (2026-10-24)
- Fee Schedule Amendment, effective 12/1/2020 — Cook County Department of Building and Zoning (2026-10-24)
- Assessor - Permits (6yjf-dfxs) — Cook County Open Data (2026-10-20)