Do I need a permit for addition or structural alteration in Unincorporated Lake County?
Yes. In Illinois, addition or structural alteration generally requires a permit, and Unincorporated Lake County is no exception.
Additions and structural alterations require a permit in essentially all Illinois jurisdictions. Illinois has no statewide residential building code for this work, so the permit threshold is set by your municipality or county. The statewide codes that took effect on 1 January 2025 apply to commercial, public and state-funded buildings. Many local codes require zoning review for lot coverage and setbacks, and properties in a mapped flood zone face additional elevation requirements. In Lake County, permits outside the cities are handled by the Lake County Planning, Building and Development Department, reachable on 847-377-2600 at https://www.lakecountyil.gov/740/Building-Permits. This office permits the unincorporated parts of Lake County. If your address sits inside a municipality, that municipality issues the permit instead. An addition means a full plan review, so confirm submittal requirements and current review times before you commission drawings.
Documents you may need
- Plat of survey / site plan showing setbacksrequired
- Construction drawings (floor plan, elevations)required
- Structural details or engineered plansLikely required
- Contractor license and insurance informationSometimes required
Possible inspections
- Footing/foundation inspection
- Framing inspection
- Rough electrical/plumbing/mechanical inspection
- Final inspection
Frequently asked questions
- Do I need a permit for addition or structural alteration in Unincorporated Lake County?
- Yes. In Illinois, addition or structural alteration generally requires a permit, and Unincorporated Lake County is no exception. Additions and structural alterations require a permit in essentially all Illinois jurisdictions. Illinois has no statewide residential building code for this work, so the permit threshold is set by your municipality or county. The statewide codes that took effect on 1 January 2025 apply to commercial, public and state-funded buildings. Many local codes require zoning review for lot coverage and setbacks, and properties in a mapped flood zone face additional elevation requirements. In Lake County, permits outside the cities are handled by the Lake County Planning, Building and Development Department, reachable on 847-377-2600 at https://www.lakecountyil.gov/740/Building-Permits. This office permits the unincorporated parts of Lake County. If your address sits inside a municipality, that municipality issues the permit instead. An addition means a full plan review, so confirm submittal requirements and current review times before you commission drawings.
- Who issues the permit in Unincorporated Lake County?
- The local building department for Unincorporated Lake County handles permitting. This page lists its contact details and online portal. Your mailing city is not always the permitting authority, so confirm the jurisdiction before you apply.
- How do I find out the exact requirements for my project?
- Run the free PermitRoadmap check for your specific project and answers. It returns the likely permits, documents, inspections, and next steps, each linked to its official source.
PermitRoadmap is an independent informational service and is not affiliated with any city, county, state agency, or permitting authority. Results are informational and do not replace confirming requirements with the local permitting authority.