To know this, you’ll need an Elevation Certificate, provided by a land surveyor. That certificate will record the height of the land above sea level, and the height of a building’s first finished floor above sea level. Subtract the height of the land from required elevation of the home, and the result is how high the building must be elevated. For example, a home in an AE-6 flood zone has an Elevation Certificate showing the grade is four feet above sea level. The building must be elevated three feet (BFE plus 1 foot).
The following equation includes mathematical symbols. In the equation the subtraction symbol (-) and the equals symbol (=) will be used:
Required height (7 feet) - Grade height (4 feet) = Height of elevated first floor above grade (3 feet). Watch the video explanation of Elevation and Freeboard for help.
The standards are higher in VE and "Coastal A" flood zones, and buildings permitted under the Building Permit Allocation System (BPAS).