County Building Permits
Williamson County, IL - 2026 Building Permit Guide
How to apply for a building permit in unincorporated Williamson County, Illinois. Permit authority, application steps, fees, and inspection requirements.
Permit Authority
unincorporated Williamson County parcels and county review workflows shown on the county site.
- Department
- Address
- Williamson County Administration Building, 407 N Monroe Street, Suite 205, Marion, IL 62959
- Phone
- (618) 998-2189
Online Permit Portal
Platform: county website PDF/application workflow; no modern self-service portal was found. • Account required: No • Submission: In-person only
Application Process
General Requirements
Required Documents
- zoning certificate, building permit application, storm water guidelines form, site plan, building plans.
- Contractor requirements
- county checklist references workers compensation insurance and contractor license.
Fees
- Plan check fee
- one-half of the building permit fee per the manual.
- Permit fee formula
- the administrative manual fee table shows valuation-based building permit fees, and plan checking fees equal one-half of the building permit fee when plan review is required.
Work That Does NOT Require a Permit
- The county manual references an agricultural exemption application in its appendices.
Inspections
How to Schedule
Typical inspection sequence: county manual indicates plan review and required approvals before permit issuance, but detailed inspection windows were not clearly published on the county page.
double fee for starting work before a permit is issued.
Additional Resources
- County home
- Supervisor of Assessments
- County phone directory
- License lookup guide: Illinois Contractor License Requirements
- Contract template: Illinois Homeowner-Contractor Agreement
- Illinois hub: Illinois Contractor License & Permit Hub
Information on this page was last verified: March 2026. Permit rules and fees change — confirm current requirements directly with the before applying.
Frequently Asked Questions
Williamson County Building Permit FAQ
- How much does a building permit cost in unincorporated Williamson County, IL?
- Fees are calculated as: the administrative manual fee table shows valuation-based building permit fees, and plan checking fees equal one-half of the building permit fee when plan review is required.. Plan check fee: one-half of the building permit fee per the manual..
- What work is exempt from building permits in unincorporated Williamson County, IL?
- The following work is generally exempt: The county manual references an agricultural exemption application in its appendices..
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