St. Louis Region
Franklin County building permits are for unincorporated work
Franklin County's Building Department handles permits and inspections for new construction in unincorporated areas, while cities may add their own requirements.
A Franklin County building project depends first on where the dirt sits. The county Building Department issues permits and inspects new construction in unincorporated Franklin County. A city, town, or the State of Missouri may still require another permit for the same job.
That is why a mailing address is a poor shortcut. A parcel can have Franklin County in the address while the work site falls inside a city or under another permitting layer. For new construction, sort the jurisdiction before the project budget gets tight.
Start with the county Building Department for unincorporated work, bring Planning and Zoning into the question when land-use rules may apply, and add the city office if the site is inside city limits.
References
Where this fits: this note belongs to Franklin County. See every local note for the county on its page.