Lake County, IL Building Safety: Building Permits (2026)
Key Facts
- Permit-exempt deck size
- 200 sq ft or less
- Permit-exempt deck height
- 16 inches above grade max
- Attached decks/patios
- Always require a permit
- Max fine
- $500 per offense (§ 150.99)
- Jurisdiction
- Unincorporated Lake County only
Summary
In unincorporated Lake County, decks need a building permit unless they stay under 200 square feet, sit no more than 16 inches above grade, are freestanding, and don't serve as a required exit or pool barrier.
Item #10 "Decks not exceeding 200 square feet in area, that are not more than 16 inches above grade at any point, are not attached to a dwelling, are not part of a pool barrier, and do not serve the exit door required by section R311.4."
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
Lake County's amended residential code (§ 150.17, amending IRC § R105.2) exempts only small, low, freestanding decks from a building permit: no more than 200 square feet, no more than 16 inches above grade at any point, not attached to the dwelling, not part of a required pool barrier, and not serving a required exit door. A deck or patio structure exceeding any of those limits, or attached to the house, needs a permit from the Planning, Building & Development Department before work starts. This applies only in unincorporated Lake County under 55 ILCS 5/5-6002 through 5-6006; Waukegan, Highland Park, Gurnee, Libertyville and other incorporated towns issue permits under their own building codes.
Violations & Fines
Building without a required permit is a fine up to $500 per offense under § 150.99, with each week of continued violation counted separately; the county may also seek an injunction to stop work.
Frequently Asked Questions
Do I need a permit for a small deck in unincorporated Lake County?
Where do I apply for a deck or patio permit?
Sources & Official References
Other rules in Lake County
Compare Lake County to another location·View the Illinois building safety overview
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