Missouri Building Permit Guides

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.

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.

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 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.