The NFIP Regulations and Building Codes require that any residential building constructed in Flood Zone Type A have the lowest floor, including basements, elevated to or above the Base Flood Elevation (BFE).
Enclosed areas are permitted under elevated buildings provided that they meet certain use restrictions and construction requirements such as the installation of flood vents to allow for the automatic entry and exit of flood waters.
This wet floodproofing technique is required for residential buildings.
With commercial buildings, elevation and the use of wet floodproofing techniques is the suggested form of mitigation. This technique can be a more cost-effective solution, and reduces the impacts the building has on surrounding floodplain in comparison to dry floodproofing techniques.