Freeboard

Additional height above the base flood elevation to which a building is protected from flooding. Freeboard helps account for modeling and mapping uncertainties associated with FIRMs, as well as a degree of anticipated future sea level rise and the hydrological effect of urbanization of the watershed, and provide additional safety. It is usually 1 to 3 feet for critical facilities. The design flood elevation (DFE) is the height of the freeboard added to the base flood elevation (BFE). In states and communities that require freeboard, buildings must be elevated or floodproofed to the DFE.