Lake County, IL Accessory Structures: Shed & Carport Rules (2026)
Shed permit rules in Lake County, IL, also referred to as storage shed, backyard shed, or accessory building regulations, set size limits, setbacks, and when a building permit is required.
Key Facts
- Permit required
- Yes, no size exemption for sheds
- Exempt structures
- Only playhouses under 120 sq ft
- Permit voids if
- Work not started within 6 months
- Completion deadline
- 6 months (sheds up to 400 sq ft)
- Applies to
- Unincorporated Lake County only
Summary
In unincorporated Lake County, sheds have no size exemption from building permits. Only playhouses and similar structures under 120 square feet skip the permit requirement, so any shed needs a Planning, Building and Development Department permit before construction begins.
Amend item 1, delete with no substitution item #2, 3, and 10. ... Item #1 "Playhouses and similar structures, provided the floor area does not exceed 120 square feet" ... 8. Permits for fences, re-siding, re-roofing, decks, electrical up grade, sheds, detached garages, screen porches and any minor alteration to an existing building that does not exceed 400 square feet are not completed and if applicable, a certificate of occupancy is not issued within six months from the date of issuance.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: 2026 S-15: Supplement contains: Local legislation current through Ord. 26-0618, passed 6-9-2026 | State legislation current through ILCS Pamphlet 2025 #5).
Full Breakdown
The county's 2024 IRC amendments rewrote the work-exempt-from-permit list at IRC § R105.2: item 1 now covers only playhouses and similar structures under 120 square feet, and items 2, 3 and 10 (fences, retaining walls, small decks) were deleted with no substitute. Sheds were never on the exempt list, so a permit is required regardless of size. Under the amended § R105.5 permit time-limits, a shed permit becomes void if construction is not substantially started within six months of issuance, and, for sheds up to 400 square feet, void again if a certificate of occupancy is not issued within six months; larger accessory buildings get one year. This chapter governs unincorporated Lake County only; Waukegan, Highland Park, Gurnee, Libertyville and other incorporated cities enforce their own building codes.
Violations & Fines
Unpermitted sheds are enforced by the Planning, Building and Development Department, which can require after-the-fact permitting, inspection, and correction before issuing a certificate of occupancy; a void permit must be reapplied for before work resumes.
Frequently Asked Questions
Do I need a permit for a small storage shed in unincorporated Lake County?
What happens if I don't finish my shed after getting a permit?
Sources & Official References
Other rules in Lake County
How Lake County compares: Shed Permit Requirements by City·Compare Lake County to another location·View the Illinois accessory structures overview
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