How building permits work in Missouri
These rules apply across Missouri. Each local guide above covers what is specific to that city, township or county: its building department and contacts, local rules, fees and inspections.
Local code adoption and what the state decides
Missouri has no mandatory statewide building code for private construction. It is a local-option state: whether a building code applies to a parcel at all, and which edition of which model code, depends on what the bodies with authority over that parcel have chosen to adopt — a county, fire protection district or municipality. Local bodies usually adopt a model code by reference: RSMo section 67.280 sets how, requiring the code to be on file with the clerk for 90 days before the vote and to stay available for public inspection. The power to adopt a code comes from other laws. So the first question on any Missouri project is not which edition applies — it is which body, if any, adopted a code over this parcel.
The three bodies that may hold the code — and the possibility that none does
Three features of Missouri practice catch projects that would be routine elsewhere. First, authority is not guaranteed to exist: a municipality may have adopted a code, the county may have adopted one over unincorporated land, a fire protection district may have adopted a fire code over both, and in parts of the state none of them has adopted anything at all. Second, counties cannot simply decide: under section 64.170 only first- and second-class counties may adopt a county building code, and a county with no code before 28 August 2001 must first win a public vote for that power — with only voters in the area the code would cover taking part, not voters inside cities. A county exercising the power appoints a building commission under section 64.180 to prepare the code. Third, even where no code is adopted, design professionals are not unconstrained: the state board for architects and engineers judges their designs against the 2018 International Building Code where no local code applies (20 CSR 2030-2.040).
A few things follow statewide rules wherever you build: modular units and manufactured homes (Public Service Commission, which applies the 2021 International Codes to modular units), and elevators and boilers (Division of Fire Safety). Parts of south-east Missouri are in the New Madrid seismic zone, so seismic design can drive the structure there.
Establish the authority first, then the ordinance, then the edition. Missouri has no statewide code, so all three questions are local and all three have to be answered for the parcel and the filing date before the requirements are knowable. A copy of the adopted code is filed with the clerk of the adopting community and kept available for public inspection.
Contractor licensing and trade permits
For the main building trades, Missouri has only one state licence, and it is not the one most people expect. There is no state general contractor licence, and no state plumbing, mechanical or HVAC licence. The exception is the optional statewide electrical contractor licence under RSMo sections 324.900 to 324.945, administered by the Office of Statewide Electrical Contractors within the Division of Professional Registration, which began accepting licence applications on 1 July 2019. The state also licenses a few specialist trades, such as elevator contractors and mechanics (Division of Fire Safety) and manufactured-home installers (Public Service Commission). Everything else is local — city or county — and in parts of the state no credential is required at all. Architects, professional engineers, land surveyors and landscape architects are separately licensed by their own state board.
A statewide electrical licence must be accepted in place of a local one. Under section 324.925 a political subdivision may keep its own local electrical licence, but it must recognise a statewide licence in lieu of it for performing work and for obtaining permits, and it may not make the holder sit any local proficiency examination. If a city or county refuses, a licence holder can complain to the state, and if it still refuses 30 days after being notified, its local sales tax money is held back until it complies. A contractor working where no local licence is required, or who already holds the local licence that place requires, does not need the statewide licence (section 324.920).
Trade permits are separate from the building permit and, on projects that require one, generally cannot be issued until the building permit is in place. Each trade follows whichever code the city has adopted for it — and because adoption is by part as well as by jurisdiction, a place may have adopted a building code and no plumbing code, or an electrical code and nothing else.
Electrical is the only main building trade with a state licence, and that licence is optional. There is no state plumbing or mechanical licence, so those credentials are local and a contractor licensed in one Missouri city or county may have to qualify again a few miles away. Where a city or county licenses construction contractors, state law requires it to collect proof of workers’ compensation cover, or a signed exemption affidavit, before issuing the licence (RSMo 287.061). Confirm the permit, the credential that actually applies and the insurance before work starts.
- Electrical work follows the electrical code the jurisdiction adopted and the referenced National Electrical Code, under a statewide electrical contractor licence or an accepted local one.
- Plumbing work follows the adopted plumbing code, under a municipally licensed plumber where the jurisdiction licenses them.
- Mechanical work follows the adopted mechanical and any energy provisions.
How permit fees are structured
| Fee component | How it works |
|---|---|
| Building permit | Set by the adopting jurisdiction, usually on project valuation or square footage; there is no state fee schedule |
| Plan review | A percentage of the permit fee or a flat charge, where the jurisdiction reviews plans at all |
| Trade permits | Separate electrical, plumbing and mechanical fees under the local schedule |
| Municipal licensing | Contractor licence or registration fees where the jurisdiction licenses; nothing where it does not |
| Zoning and use | Zoning, occupancy and, in some places, business licence fees |
| Re-inspections and revisions | Additional fees for failed inspections, revisions and expired permits |
Permit validity
Approvals do not stay live indefinitely. Permit validity periods are set by the adopting jurisdiction rather than by statute, so they differ from place to place and cannot be assumed from a previous job. On phased or financed work, confirm the expiry window in the local ordinance and keep the permit alive with progress inspections.