Vermilion Parish, LA Environmental Rules: Flood Elevation Requirements (2026)

Sec. 22-67 of the Vermilion Parish Code sets the elevation rule wherever base flood elevation data has been provided under Sec. 22-7, 22-44(8) or 22-68(c). Sec. 22-1 defines base flood elevation as the water surface elevation shown on the FIRM and in the flood insurance study for the flood that has a one percent chance of being equaled or exceeded in any given year.

Residential construction comes first. New construction and substantial improvement of a residential structure must have the lowest floor, including a basement, elevated to or above the base flood elevation, and a registered professional engineer, architect or land surveyor must submit a certification to the floodplain administrator. Sec. 22-1 counts an improvement as substantial when its cost equals or exceeds 50 percent of the market value of the structure before construction starts.

Nonresidential buildings have two routes. The lowest floor can sit at or above the base flood level, or the structure and its utility and sanitary facilities can be designed watertight below that level, with walls substantially impermeable to water. The floodproofing route requires a registered professional engineer or architect to develop or review the design and certify it, and the floodplain administrator keeps a record of the elevation, in relation to mean sea level, to which the building is floodproofed.

Fully enclosed areas below the lowest floor usable solely for parking of vehicles, building access or storage must equalize flood forces. The default design uses a minimum of two openings on separate walls, with total net area of not less than one square inch for every square foot of enclosed area, and the bottom of every opening no higher than one foot above grade. Manufactured homes must sit with the bottom of the longitudinal I-beam at or above the base flood elevation, or in some existing parks on chassis supported by piers no less than 36 inches in height above grade.

In AO and AH shallow flooding zones, Sec. 22-69 requires the lowest floor at or above the base flood elevation or the highest adjacent grade at least as high as the depth number on the FIRM, at least two feet if no depth number is specified. Sec. 22-45(a)(1) requires every permit application to state the lowest floor elevation in relation to mean sea level. Chapter 22 does not use the word freeboard, so the printed benchmark is the base flood elevation itself.