Kirkwood, MO Environmental Rules: Flood Elevation Requirements (2026)

Where base flood elevation data exist for a mapped A or AE zone, § 5-72(B)(1)(a) requires new construction or a substantial improvement of a residential structure, including a manufactured home, to have its lowest floor, including any basement, elevated to one foot above the base flood elevation, a one-foot freeboard margin above the minimum FEMA standard. Subsection (b) gives nonresidential buildings, such as commercial or industrial structures, the same one-foot elevation option or a floodproofing alternative: the structure can instead be built watertight below the base flood elevation, with walls substantially impermeable to water and components able to resist hydrostatic and hydrodynamic loads, but only if a registered professional engineer or architect certifies the design and files that certification with the Floodplain Administrator under § 5-71(C)(9).

Any fully enclosed area below the lowest floor used only for parking, building access or storage, and that can flood, must include a minimum of two openings totaling at least one square inch of net area for every square foot of enclosed area, with the bottom of every opening no higher than one foot above grade, so floodwater can enter and drain automatically. Manufactured homes get the same one-foot-above-base-flood-elevation standard under § 5-72(C), anchored against flotation, collapse or lateral movement.