Southaven, MS Environmental Rules: Flood Elevation Requirements (2026)

Section 6-31 applies in special flood hazard areas designated on the community's FIRM where base flood elevation data have been provided, excluding the community flood hazard areas and the Coastal AE Zone. Subsection (1) covers residential construction: the lowest floor, including basement, is elevated no lower than eighteen inches above the base flood elevation, which the code calls the community freeboard. Subsection (2) applies the same eighteen inches to commercial, industrial and nonresidential buildings and to manufactured homes.

Non-residential buildings in all A zones can be floodproofed instead of elevated, but every area below the base flood elevation plus the minimum eighteen-inch community freeboard must be water tight with walls substantially impermeable to the passage of water. Dry floodproofing is allowed only where flood velocities are less than or equal to five feet per second. A registered professional engineer or architect certifies the design, and the design professional supplies a flood emergency operation plan and an inspection and maintenance plan.

The definitions in Section 6-6 tie the terms together: the flood protection elevation is the base flood elevation plus the community freeboard. Section 6-21 requires the elevation certificate on FEMA Form 81-31 and states that floodproofing must be eighteen inches above the base flood elevation. It also requires lots removed from the special flood hazard area by a letter of map revision based on fill to meet the freeboard elevation when the top of fill is below it.

Enclosures below an elevated building are limited under subsection (4) to 299 square feet, used only for parking, building access and storage, with at least two openings on different sides, one square inch of net opening per square foot of enclosed area, and opening bottoms no higher than one foot above interior grade. Manufactured homes take the eighteen inches too under subsection (5). Where no base flood elevation data exist, Section 6-32(4) requires the lowest floor at least forty-two inches above the highest adjacent grade.