City Building Permits
O'Fallon, MO - 2026 Building Permit Guide
How to apply for a building permit in O'Fallon, Missouri. Permit authority, application steps, fees, and inspection requirements.
Permit Authority
Applies within the City of O'Fallon municipal limits in St. Charles County.
- Department
- City of O'Fallon Planning and Development Department
- Address
- 100 North Main St., O'Fallon, MO 63366
- Phone
- 636-379-5594
- Website
- https://www.ofallon.mo.us/
Online Permit Portal
Platform: • Account required: No • Submission: In-person only
Additional resources:
Application Process
- Verify permit type with Planning and Development and check for zoning, engineering, or right of way reviews.
- Prepare permit application, plans, and contractor information.
- Submit through the City permit process.
- City completes review and returns comments if revisions are required.
- Fees are paid after approval.
- Permit is issued and inspections are scheduled with the City.
Source: City of O'Fallon Planning and Development Department
General Requirements
New construction, additions, remodels, accessory structures, many trade permits, and other regulated work under city code.
Required Documents
- Permit form
- Plans and specifications
- Site plan or plat information as applicable
- Contractor data
- Project valuation
- Building code
- City enforces locally adopted construction codes; exact edition should be confirmed from city ordinance before application.
- Contractor requirements
- City administers contractor licensing and registration tied to permit issuance.
Fees
- Permit fee formula
- Mix of valuation-based and permit-type specific fees.
- Payment note
- Paid through the City permit process.
Fees change. Verify current amounts at the official fee schedule.
Work That Does NOT Require a Permit
Contact the City of O'Fallon Planning and Development Department to confirm whether your project requires a permit before starting work.
Inspections
How to Schedule
- City after permit issuance (phone)
Typical inspection sequence: Footing/foundation, rough framing and trades, then final inspections.
Additional Resources
- Building code: City enforces locally adopted construction codes; exact edition should be confirmed from city ordinance before application.
- Zoning information: View zoning info
- O'Fallon GIS Maps
- License lookup guide: Missouri Contractor License Requirements
- Contract template: Missouri Homeowner-Contractor Agreement
- Missouri hub: Missouri Contractor License & Permit Hub
Information on this page was last verified: March 2026. Permit rules and fees change — confirm current requirements directly with the City of O'Fallon Planning and Development Department before applying.
Frequently Asked Questions
O'Fallon Building Permit FAQ
- Do I need a building permit in O'Fallon, MO?
- New construction, additions, remodels, accessory structures, many trade permits, and other regulated work under city code.
- How much does a building permit cost in O'Fallon, MO?
- Fees are calculated as: Mix of valuation-based and permit-type specific fees..
- How do I apply for a building permit in O'Fallon, MO?
- 1. Verify permit type with Planning and Development and check for zoning, engineering, or right of way reviews. 2. Prepare permit application, plans, and contractor information. 3. Submit through the City permit process. 4. City completes review and returns comments if revisions are required. 5. Fees are paid after approval. 6. Permit is issued and inspections are scheduled with the City.
- How do I schedule a building inspection in O'Fallon, MO?
- Inspections can be scheduled via: City after permit issuance.
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