New construction or substantial improvements of elevated and crawl space buildings that include fully-enclosed areas formed by foundation and other walls below the design flood elevation shall be designed to preclude finished living space, and to allow for the entry and exit of floodwaters to automatically equalize hydrostatic flood forces on the walls.
   (A)   Designs for complying with this requirement must either be certified by a professional engineer or architect, or meet the following minimum criteria:
      (1)   Provide a minimum of two openings, located on two different walls of the enclosure, having a total net area of not less than one square inch for every square foot of enclosed area subject to flooding;
      (2)   The bottom of all openings shall be no higher than one foot above grade; and
      (3)   Openings may be equipped with screens, louvers, valves, or other coverings or devices, provided they permit the automatic flow of floodwaters in both directions.
   (B)   For elevated buildings, fully-enclosed areas below the design flood elevation shall not exceed 200 square feet cumulatively. The fully enclosed areas cannot be temperature controlled.
   (C)   Elevated buildings shall be supported by piers, piles or other open foundation systems. Non-load-bearing partitions may be installed around the perimeter of the foundation area. These partitions shall not be considered enclosure walls for the purposes of division (B) above, provided they meet the following conditions:
      (1)   Each section of partition wall between piers or other vertical structural supports shall be provided with permanent openings, having a total net area of not less than 40% of the total partition area;
      (2)   Each partition wall must have openings within one foot of grade to allow for the entry and exit of floodwaters as per division (A) above;
      (3)   The area within the perimeter partitions shall not be divided or finished into separate rooms, except as allowed in division (B) above; and
      (4)   Access to the enclosed area(s) shall be the minimum necessary to allow for parking of vehicles (garage door), or limited storage (standard exterior door), or entry to the living area (stairway or elevator).
   (D)   A nonconversion agreement, as supplied by the Town Inspection Division, is required to be executed for all new elevated residential construction and substantial improvements with enclosed areas below the design flood elevation. The nonconversion agreement must be registered with the Charleston County Register of Mesne Conveyance office, and a recorded copy must be returned to the Building Official prior to the issuance of a certificate of occupancy.
(‘81 Code, § 152.05 b.) (Ord. passed 3-5-84; Am. Ord. passed 6-11-91; Am. Ord. passed 12-17-91; Am. Ord. passed 5-19-92; Am. Ord. 07055, passed 9-11-07; Am. Ord. 18039, passed 6-14-18)