Design Flood Elevation (DFE)

Locally adopted regulatory flood elevation; it is the minimum elevation to which a structure must be elevated or floodproofed. DFE is the sum of the base flood elevation and freeboard, based a building’s structural category. In areas designated as Zone AO on a community’s flood map, the DFE is the elevation of the highest existing grade of a building’s perimeter plus the depth number specified on the flood hazard map. In areas designated as Zone AO where a depth is not specified on the map, the depth is two feet. Note that if a community regulates based on the Flood Insurance Rate Map, the DFE is the same as the base flood elevation. But if a community’s floodplain regulations are based on a different flood hazard map, a lower frequency flood, or the inclusion of freeboard, the DFE must be at least as high as the base flood elevation.