St. Louis, MO Environmental Rules: Flood Elevation Requirements (2026)
Key Facts
- Freeboard required
- 1 foot above base flood elevation
- Applies in
- FEMA A and AE flood zones
- Permit needed
- Floodplain development permit
- Certification
- Licensed engineer or architect required
- Max fine
- $500/day, misdemeanor
Summary
New construction and substantial improvements in St. Louis's mapped flood hazard areas must have the lowest floor, including any basement, built at least one foot above the base flood elevation before the city will sign off.
New construction or substantial improvement of any residential structures, including manufactured homes, shall have the lowest floor, including basement, elevated to or above one foot above base flood elevation.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 11).
Full Breakdown
St. Louis adopted the 2018 International Building Code with a local floodplain-management appendix (Appendix G) covering all numbered and unnumbered A and AE zones on the city's FEMA Flood Insurance Rate Map. A floodplain development permit from the Floodplain Administrator is required before any building, fill, or substantial improvement in these zones. Residential structures must have the lowest floor elevated to at least one foot above base flood elevation (BFE); nonresidential structures must either meet that same elevation or be engineer-certified as floodproofed and watertight below BFE. A registered engineer or architect must certify compliance, and an elevation certificate is required before vertical construction proceeds past the lowest floor.
Violations & Fines
Violating the floodplain appendix is a misdemeanor: fines up to $500 plus costs, with each day of continued violation counted as a separate offense (§ G107.1).
Frequently Asked Questions
How much freeboard does St. Louis require above base flood elevation?
Who signs off on flood-zone construction in St. Louis?
Sources & Official References
Other rules in St. Louis
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