In all areas of special flood hazards:
A. All new construction and substantial improvements of nonresidential structures are required to:
1. Have the lowest floor (including basement) elevated to or above the base flood level; or
2. Together with attendant utility and sanitary facilities, be designed so that below the base flood level the structure is watertight with walls substantially impermeable to the passage of water and with structural components having the capability of resisting hydrostatic and hydrodynamic loads and effects of buoyancy.
B. Where a nonresidential structure is intended to be made watertight below the base flood level:
1. A registered professional engineer or architect shall develop and/or review structural design, specifications, and plans for the construction, and shall certify that the design and methods of construction are in accordance with accepted standards of practice for meeting the applicable provisions of subsection (A)(2) of this section; or
2. The attendant utility and sanitary facilities shall be completely floodproofed; and
3. A record of such certificates which includes the specific elevation (in relation to mean sea level) to which such structures are floodproofed shall be maintained with the official designated by the community (44 CFR 59.22(a)(9)(iii)).
C. For all new construction and substantial improvements, fully enclosed areas below the lowest floor are restricted for use solely for parking of vehicles, building access or storage in an area other than a basement. In areas subject to flooding, buildings shall be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for the entry and exit of floodwaters. Designs for meeting this requirement must either be certified by a registered professional engineer or architect or meet or exceed the following minimum criteria: A minimum of two openings having a total net area of not less than one square inch for every square foot of enclosed area subject to flooding shall be provided. The bottom of all openings shall be no higher than one foot above grade. Openings may be equipped with screens, louvers, valves, or other coverings or devices; provided, that they permit the automatic entry and exit of floodwaters.