Lake County, IL Accessory Structures: ADU Rental Restrictions (2026)
Key Facts
- Owner occupancy
- required in house or ADU
- Governs
- unincorporated Lake County only
- Eligible districts
- AG, RE, E, R-1
- Minimum lot size
- 80,000 sq ft
- Max units per lot
- one ADU
Summary
In unincorporated Lake County, an accessory dwelling unit cannot be rented out as a separate income property while the owner lives elsewhere: the property owner must occupy either the principal house or the ADU itself, per County Code § 151.113(D)(3)(a).
The combined total number of individuals that reside in the principal and accessory dwelling units shall not exceed the number that is allowed for a single household... The owner of the real property upon which the accessory dwelling unit is located must occupy either the principal or accessory dwelling unit.
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 Unified Development Ordinance allows detached or attached accessory dwelling units on qualifying lots in the AG, RE, E and R-1 districts of at least 80,000 square feet, but ties that right to occupancy: under § 151.113(D)(3)(a), the owner of the property must occupy either the principal dwelling or the accessory dwelling unit. That bars the common investor model of renting out both units to tenants while the owner lives elsewhere. The rule applies only in unincorporated Lake County (§ 151.003). Waukegan, Highland Park, Gurnee, Libertyville and other incorporated towns set their own ADU rules.
Violations & Fines
Renting an ADU without the required owner occupancy is a zoning code violation, handled through the county's standard zoning enforcement process rather than a special ADU penalty.
Frequently Asked Questions
Can I rent out my Lake County ADU while living off-site?
Does this rule apply inside Waukegan or Highland Park?
Sources & Official References
Other rules in Lake County
Compare Lake County to another location·View the Illinois accessory structures overview
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