Administrative overview · FIPS 29071
Franklin County permit authority
The first compliance decision is jurisdictional: identify the office with statutory authority over your parcel, then use its filing and inspection sequence to keep the project moving.
Jurisdictional status
County
This county profile is the primary starting point for unincorporated-area permitting.
Responsible agency
Franklin County Building Department and Planning & Zoning Department
For a project in or near Franklin County, this office is the identified point of contact for permit intake, statutory code enforcement, plan review coordination, and inspection release conditions. Confirm the parcel’s boundary and project type before relying on the county lane.
Direct contact
636-583-6384 (Building Department); 636-583-6369 (Planning & Zoning)
Call before mobilizing if the project has a boundary, occupancy, fire, septic, or utility question.
Permit counter
Franklin County Building Department, 400 E. Locust Street, Room 006, Union, MO 63084
Operating hours
Monday-Friday, 8:00 AM-4:30 PM for Planning & Zoning; Building Department applications are accepted Monday-Friday, 8:00 AM-5:00 PM, with applications received after 4:00 PM post-dated to the next business day.
Review expectation
N/A for ordinary building permits; the county publishes no fixed review timeline. Conditional-use applications must generally be submitted at least 30 days before the next Planning & Zoning Commission meeting, and staffing/workload may affect response times.
Compliance workbench
Choose the next project decision.
Apply online
Open the verified digital gateway, application form, and review timeline.
Open guide →Fees & penalties
Understand fee schedules, enforcement exposure, and stop-work liabilities.
Open guide →Codes & exemptions
Read the code framework, minor-work exemptions, and inspection lane.
Open guide →Agency website
Visit the primary public source for current notices and contact changes.
Open guide →Source trail
Official sources for this profile
Use these direct agency or licensing links to confirm current instructions before you file, pay, or schedule work. External pages control if their information differs from this directory.
Project questions
Frequently asked questions for Franklin County
Who handles permitting for this jurisdiction?
Franklin County Building Department and Planning & Zoning Department is the identified county-level authority for this profile. Confirm that the property is in its service area before filing.
How should I begin an application?
Begin with the online permit gateway listed in the application guide. If the portal does not recognize the address or project type, contact 636-583-6384 (Building Department); 636-583-6369 (Planning & Zoning).
How long might review take?
N/A for ordinary building permits; the county publishes no fixed review timeline. Conditional-use applications must generally be submitted at least 30 days before the next Planning & Zoning Commission meeting, and staffing/workload may affect response times.
How are inspections scheduled?
The Building Department issues permits and inspects new construction in unincorporated Franklin County. The county publishes inspection guidelines by request; contact 636-583-6384 or building@franklinmo.gov to schedule inspections and obtain the current guidelines. Floodplain applications may require longer review and SEMA forms.
Which codes and exemptions should I review?
For unincorporated Franklin County, the county lists the 2021 International Building, Residential, Mechanical, Plumbing, Fire, ICC Electrical, and Swimming Pool & Spa Codes, plus the 2020 National Electrical Code. The county's on-site sewage ordinance was amended September 23, 2025 and became effective October 1, 2025; the Flood Damage Prevention Ordinance and Unified Land-Use Regulations also apply. Franklin County requires permits for construction and right-of-way use, and the county notes that municipalities and Missouri may require additional permits. The current building page publishes no broad cosmetic/minor-work exemption list; contact the Building Department to determine whether a specific repair or alteration requires a permit.