Every location within a regulated flood zone has a pre-determined flood level, known as the Base Flood Elevation (BFE). In type "A" flood zones, the height of a building is measured to Finished First Floor, usually referred to as the first habitable floor.
AE Flood Zones
For example, an "AE-6" flood zone indicates when a substantial flood event occurs, minimum flood levels at this location are expected to be six feet above sea level. Current building codes require Substantially Improved buildings be elevated one-foot higher than the BFE (known as the Design Flood Elevation or DFE). Therefore, a home within an "AE-6" flood zone would need to be elevated to at least seven-feet above sea level.
VE and Coastal A Flood Zones
Type "VE" and "Coastal A" flood zones are located along shorelines and have more stringent construction standards. The appropriate flood level for these buildings is measured at the lowest horizontal cross-member. The underside of that cross-member must be one foot higher than the Base Flood Elevation for the specific site.
If you’re seeking a building permit under the Building Permit Allocation System (BPAS), the minimum height requirement is 1.5-feet above BFE.