(A) Residential construction. New construction or the substantial improvement of any residential structure, including manufactured homes, shall have the lowest floor elevated no lower than one feet above the base flood elevation. No basements are permitted. Should solid foundation perimeter walls be used to elevate a structure, openings sufficient to facilitate the unimpeded movements of flood waters shall be provided in accordance with subsection (E) below.
(B) Non-residential construction. New construction or the substantial improvement of any commercial, industrial or non-residential structure, including manufactured homes, shall have the lowest floor elevated no lower than one or more feet above the level of the base flood elevation. Should solid foundation perimeter walls be used to elevate a structure, openings sufficient to facilitate the unimpeded movements of flood waters shall be provided in accordance with subsection (E) below. No basements are permitted. Structures located in A Zones may be flood-proofed in lieu of elevation; provided that, all areas of the structure below the required elevation are water-tight with walls substantially impermeable to the passage of water, using structural components having the capability of resisting hydrostatic and hydrodynamic loads and the effect of buoyancy. A registered, professional engineer or architect shall certify that the standards of this subsection (B) are satisfied. Such certifications shall be provided to the official as set forth in § 20-42(B)(7) and (B)(9) of this chapter. A variance may be considered for wet flood-proofing agricultural structures in accordance with the criteria outlined in § 20-124 of this chapter. Agricultural structures not meeting the criteria of § 20-124 of this chapter must meet the non-residential construction standards and all other applicable provisions of this chapter. Structures which are flood-proofed are required to have an approved maintenance plan with an annual exercise. The maintenance plan must be approved by the local administrator and notification of the annual exercise shall be provided to same.
(C) Manufactured homes.
(1) Manufactured homes that are placed or substantially improved on sites outside a manufactured home park or subdivision, in a new manufactured home park or subdivision, in an expansion to an existing manufactured home park or subdivision, or in an existing manufactured home park or subdivision on which a manufactured home has incurred substantial damage as the result of a flood, must be elevated on a permanent foundation such that the lowest floor of the manufactured home is elevated no lower than one feet above the base flood elevation and must be securely anchored to an adequately anchored foundation system to resist flotation, collapse and lateral movement.
(2) Manufactured homes that are to be placed or substantially improved on sites in an existing manufactured home park or subdivision that are not subject to the provisions of subsection (C)(1) above must be elevated so that the lowest floor of the manufactured home is elevated no lower than one feet above the base flood elevation, and must be securely anchored to an adequately anchored foundation to resist flotation, collapse and lateral movement.
(3) Manufactured homes shall be anchored to prevent flotation, collapse or lateral movement. For the purpose of this requirement, manufactured homes must be anchored to resist flotation, collapse or lateral movement in accordance with § 19-425.39 of the South Carolina Manufactured Housing Board Regulations, effective date 5-25-1990. Additionally, when the elevation requirement would be met by an elevation of the chassis at least 36 inches or less above the grade at the site, the chassis shall be supported by reinforced piers or other foundation elements of at least equivalent strength. When the elevation of the chassis is above 36 inches in height an engineering certification is required.
(4) An evacuation plan must be developed for the evacuation of all residents of all new, substantially improved or substantially damaged manufactured home parks or subdivisions located within flood-prone areas. This plan shall be filed with and approved by the local administrator and the local emergency preparedness coordinator.
(D) Recreational vehicles. A recreational vehicle is ready for highway use if it is on wheels or a jacking system, is attached to the site only by quick-disconnect type utilities and security devices, and has no permanently attached additions. Recreational vehicles placed on sites shall either be on the site for fewer than 180 consecutive days and be fully licensed and ready for highway use, or meet the requirements of §§ 20-42 and 20-62 of this chapter and subsection (C) above.
(E) Elevated buildings. New construction or substantial improvements of elevated buildings that include fully enclosed areas that are usable solely for the parking of vehicles, building access or storage in an area other than a basement, and which are subject to flooding shall be designed to preclude finished space and be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for the entry and exit of flood waters.
(1) Minimum criteria. Designs for complying with the requirement of this subsection (E) must either be certified by a professional engineer or architect or meet the following minimum criteria:
(a) Provide a minimum of two openings on different walls having a total net area of not less than one square inch for every square foot of enclosed area subject to flooding;
(b) The bottom of all openings shall be no higher than one foot above grade;
(c) Openings may be equipped with screens, louvers, valves or other coverings or devices; provided, they permit the automatic flow of flood waters in both directions; and
(d) Fill placed around foundation walls must be graded so that the grade inside the enclosed area is equal to or higher than the adjacent grade outside the building on at least one side of the building.
(2) Hazardous velocities. Hydrodynamic pressure must be considered in the design of any foundation system where velocity waters or the potential for debris flow exists. If flood velocities are excessive (greater than five feet per second), foundation systems other than solid foundations walls should be considered so that obstructions to damaging flood flows are minimized.
(3) Access. Access to the enclosed area shall be the minimum necessary to allow for:
(a) The parking of vehicles (garage door);
(b) The limited storage of maintenance equipment used in connection with the premises (standard exterior door); or
(c) Entry into the living area (stairway or elevator).
(4) Partitioning/finishing interior prohibited. The interior portion of such enclosed area shall not be partitioned or finished into separate rooms, except to enclose a single storage area and must be void of utilities, except for essential lighting as required, and cannot be temperature controlled. One wet location switch or outlet connected to a ground fault interrupt breaker may be installed below the required lowest floor elevation specified in subsections (E)(1) through (E)(3) above.
(5) Flood-resistant material. All construction materials below the required lowest floor elevation specified in subsections (E)(1) through (E)(3) above shall be of flood-resistant materials.
(Ord. 102, passed 2-3-2003)