New construction and substantial improvement of any commercial, industrial or other nonresidential structure shall either have the lowest floor, including basement, elevated one foot or more* above the base flood elevation; or, together with attendant utility and sanitary facilities, shall:
A. Be floodproofed so that below one foot or more above the base flood level the structure is watertight with walls substantially impermeable to the passage of water;
B. Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy;
C. Be certified by a registered professional engineer or architect that the design and methods of construction are in accordance with accepted standards of practice for meeting provisions of this subsection based on their development and/or review of the structural design, specifications and plans. Such certifications shall be provided to the official as set forth in SPMC 15.16.180(B);
D. Nonresidential structures that are elevated, not floodproofed, must meet the same standards for space below the lowest floor as described in SPMC 15.16.290.
*Applicants who are floodproofing nonresidential buildings should be notified that flood insurance premiums will be based on rates that are one foot below the floodproofed level (e.g., a building floodproofed to the base flood level will be rated as one foot below). Floodproofing the building an additional foot will reduce insurance premiums significantly.