How much does a building permit cost in unincorporated Warren County, MO?

The minimum permit fee is No charge for improvements/additions of 120 sq ft or less; otherwise structure permit fees start at $60 depending on scope. Fees are calculated as: Mostly flat by project type and size; some items are flat fees, and commercial buildings are charged a flat base plus 5 cents per sq ft. Plan check fee: Not shown as a separate plan check line item in the public fee schedule.

How long does it take to get a building permit in unincorporated Warren County, MO?

Typical processing time is Not stated publicly.

What work is exempt from building permits in unincorporated Warren County, MO?

The following work is generally exempt: No comprehensive public exempt-work list was found for the county structure permit process; The fee schedule does show a no-charge tier for improvements/additions 120 sq ft or less, but the structure packet still says all structures in unincorporated Warren County require a permit.

How do I schedule a building inspection in unincorporated Warren County, MO?

Inspections can be scheduled via: Coordinate with Planning and Zoning and the Sanitarian; the packet suggests calling before coming in so staff will be available.

County Building Permits

Warren County, MO - 2026 Building Permit Guide

How to apply for a building permit in unincorporated Warren County, Missouri. Permit authority, application steps, fees, and inspection requirements.

Missouri Updated March 2026

Permit Authority

County zoning and structure permits cover unincorporated Warren County. The county states that unincorporated areas do not currently require a Certificate of Occupancy. Floodplain review is handled through the county, and electric stickers are also issued through this process. Warrenton and Wright City fire districts add separate fire-permit requirements in their service areas

Department: Warren County Planning and Zoning
Address: 101 Mockingbird Ln, Suite 201, Warrenton, MO 63383
Phone: 636-456-3044
Email: broemer@warrencountymo.org
Website: https://warrencountymo.org/planning-and-zoning/

Online Permit Portal

Open No online county permit portal located in public sources; applications are handled by forms and in-person or email submission

Platform: None found • Account required: No • Submission: In-person only

Additional resources:

Application Process

Confirm the parcel is in unincorporated Warren County and not inside a city district
If the project will use septic, obtain a soil evaluation and septic permit first
If the parcel is in a floodplain, complete floodplain review and required documentation
Submit the structure permit application, plans or home layout, deed or title documentation if needed, photo ID, address assignment, and any notarized authorization if applying for someone else
Pay the permit fee to the Warren County Treasurer
Receive the structure permit and, if applicable, temporary or permanent electric sticker
For septic systems, obtain final inspection approval before permanent electric service is released

Typical processing time: Not stated publicly

Source: Warren County Planning and Zoning

General Requirements

All structures in unincorporated Warren County require a permit, regardless of size or use

Required Documents

When a permit is required: All structures in unincorporated Warren County require a permit, regardless of size or use
Required documents: Copy of plans or home layout, title or bill of sale for mobile or modular units, address assignment, recorded warranty deed if recently purchased, photo ID, notarized affidavit if someone else applies, and additional floodplain or septic materials when applicable
Permit validity/expiration: Structure permits expire 1 year from issuance
Owner-builder rules if available: The property owner should obtain the permit; if unable, a notarized affidavit can authorize another person
Contractor license requirements: No county contractor license requirement located in public sources; outside contractors must still secure required permits and approvals
Building code adopted: Warren County adopts zoning and floodplain regulations. The county states it cannot administer a building code for new construction because it is a third-class county. Floodplain ordinance and zoning codes apply

Permit validity: Structure permits expire 1 year from issuance
Building code: Warren County adopts zoning and floodplain regulations. The county states it cannot administer a building code for new construction because it is a third-class county. Floodplain ordinance and zoning codes apply
Owner-builder: The property owner should obtain the permit; if unable, a notarized affidavit can authorize another person
Contractor requirements: No county contractor license requirement located in public sources; outside contractors must still secure required permits and approvals

Fees

Minimum permit fee: No charge for improvements/additions of 120 sq ft or less; otherwise structure permit fees start at $60 depending on scope
Plan check fee: Not shown as a separate plan check line item in the public fee schedule
Permit fee formula: Mostly flat by project type and size; some items are flat fees, and commercial buildings are charged a flat base plus 5 cents per sq ft
Reinspection fee: Fee doubles if the correct permit is not obtained before work starts. Septic holding tank late fee may apply
Payment note: Checks payable to Warren County Treasurer

Fees change. Verify current amounts at the official fee schedule.

Work That Does NOT Require a Permit

Contact the Warren County Planning and Zoning to confirm whether your project requires a permit before starting work.

Inspections

How to Schedule

Coordinate with Planning and Zoning and the Sanitarian; the packet suggests calling before coming in so staff will be available ()

Inspection hours: Office hours Monday through Friday, 8:00 am to 4:30 pm

Typical inspection sequence: Soil evaluation and septic review if needed, floodplain review if applicable, permit issuance, electric sticker issuance, septic final inspection if relevant

Additional Resources

Building code: Warren County adopts zoning and floodplain regulations. The county states it cannot administer a building code for new construction because it is a third-class county. Floodplain ordinance and zoning codes apply
Zoning information: View zoning info
warrencountymo.org
warrencountymo.org
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 Warren County Planning and Zoning before applying.

Frequently Asked Questions

Warren County Building Permit FAQ

Do I need a building permit in unincorporated Warren County, MO?: All structures in unincorporated Warren County require a permit, regardless of size or use
How much does a building permit cost in unincorporated Warren County, MO?: The minimum permit fee is No charge for improvements/additions of 120 sq ft or less; otherwise structure permit fees start at $60 depending on scope. Fees are calculated as: Mostly flat by project type and size; some items are flat fees, and commercial buildings are charged a flat base plus 5 cents per sq ft. Plan check fee: Not shown as a separate plan check line item in the public fee schedule.
How do I apply for a building permit in unincorporated Warren County, MO?: 1. Confirm the parcel is in unincorporated Warren County and not inside a city district 2. If the project will use septic, obtain a soil evaluation and septic permit first 3. If the parcel is in a floodplain, complete floodplain review and required documentation 4. Submit the structure permit application, plans or home layout, deed or title documentation if needed, photo ID, address assignment, and any notarized authorization if applying for someone else 5. Pay the permit fee to the Warren County Treasurer 6. Receive the structure permit and, if applicable, temporary or permanent electric sticker 7. For septic systems, obtain final inspection approval before permanent electric service is released
How long does it take to get a building permit in unincorporated Warren County, MO?: Typical processing time is Not stated publicly.
What work is exempt from building permits in unincorporated Warren County, MO?: The following work is generally exempt: No comprehensive public exempt-work list was found for the county structure permit process; The fee schedule does show a no-charge tier for improvements/additions 120 sq ft or less, but the structure packet still says all structures in unincorporated Warren County require a permit.
How do I schedule a building inspection in unincorporated Warren County, MO?: Inspections can be scheduled via: Coordinate with Planning and Zoning and the Sanitarian; the packet suggests calling before coming in so staff will be available.

Need help with your project?

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Important: This page is an educational resource provided by jaspector.com. It is not legal advice, and it does not substitute for official guidance from the permit authority listed above. Permit requirements, fees, and processes change frequently. Always verify current requirements directly with the issuing department before beginning any construction project. Use of this page does not create an attorney-client relationship. Jaspector assumes no liability for any outcomes arising from reliance on this information.

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