§ 26-41. Specific standards.

(a)

In all areas with the letter "A" as its first flood zone attribute (A, AE, AO, and AH), the following provisions are required:

(1)

All new construction and substantial improvements of residential structures within zones AE and AH on the Charleston County FIRM, shall be elevated so that the top of the lowest floor level of the lowest floor (including basement) is elevated to or above one foot above the base flood elevation.

(2)

All new construction and substantial improvements of nonresidential structures within zones AE and AH on the community FIRM shall have:

a.

The lowest floor (including basement) elevated to or above one foot above the base flood level; or

b.

Together with attendant utility and sanitary facilities, be designed so that below one foot above 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.

(3)

Where a nonresidential structure is intended to be made watertight below the base flood level:

a.

A registered professional engineer or architect licensed in South Carolina 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)b. of this section, including but not limited to, "Floodproofing Nonresidential Structures (FEMA 102)", as published by the Federal Emergency Management Agency incorporated herein by reference; and

b.

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 building official.

(4)

Enclosed areas below the lowest floor, including foundation crawl space areas, shall be designed to automatically equalize hydrostatic and hydrodynamic 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 licensed in South Carolina 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. The area of the opening is the net clear opening calculated as the open area (excluding area of screening or other coverings that prohibit the free flow of water through the opening).

(5)

Enclosed areas below the lowest floor, with the exception of foundation crawl spaces, shall be the minimum necessary to allow for parking of vehicles, limited storage, and access to the primary occupancy (stairway or elevator).

(b)

Specific standards high hazard areas "V" or VE zones located within the areas of special flood hazard are areas designated as coastal high hazard areas. These areas have special flood hazards associated with wave wash, and therefore, the following provisions shall apply:

(1)

All new construction within zones V and VE on the Charleston County FIRM is located landward of the reach of mean high tide.

(2)

Provide that all new construction and substantial improvements in zones V and VE, if base flood elevation data is available on the Charleston County FIRM, are elevated on pilings and columns so that:

a.

The bottom of the lowest horizontal structural member of the lowest floor (excluding the pilings or columns) is elevated to or above one foot above the base flood level; and

b.

The pile or column foundation and structure attached thereto is anchored to resist flotation, collapse and lateral movement due to the effects of wind and water loads acting simultaneously on all building components. Water loading values used shall be those associated with the base flood. Wind loading values used shall be those required by the International Building Code or International Residential Code as adopted and periodically amended by the South Carolina Department of Labor, Licensing and Regulation. A registered professional engineer or architect licensed in South Carolina shall develop the structural design, specifications and plans for construction, and shall certify that the design and methods of construction to be used are in accordance with accepted standards of practice for meeting the provisions of subsections (b)(2)a. and this subsection b. of this section of the Code of Ordinances, Charleston County, South Carolina.

(3)

New construction and substantial improvements within zones V and VE on the Charleston County FIRM have the space below the lowest floor either free of obstruction or constructed with nonsupporting breakaway walls, open wood latticework, or insect screening intended to collapse under wind and water loads without causing collapse, displacement, or other structural damage to the elevated portion of the building or supporting foundation system. For the purposes of this section, a breakaway wall shall have a design safe loading resistance of not less than ten and no more than 20 pounds per square foot. Use of breakaway walls which exceed a design safe loading resistance of 20 pounds per square foot (either by design or when so required by local or state codes) may be permitted only if a registered professional engineer or architect licensed in South Carolina certifies that the designs proposed meet the following conditions:

a.

Breakaway wall collapse shall result from a water load less than that which would occur during the base flood; and

b.

The elevated portion of the building and supporting foundations system shall not be subject to collapse, displacement, or other structural damage due to the effects of wind and water loads acting simultaneously on all building components (structural and nonstructural). Water loading values used shall be those associated with the base flood. Wind loading values used shall be those required by applicable state or local building standards. Such enclosed space shall be useable solely for parking of vehicles, building access or storage.

(4)

There shall be no fill used as structural support. Noncompacted fill may be used around the perimeter of a building for landscaping/aesthetic purposes, provided the fill will wash out from storm surge, thereby rendering the building free of obstruction prior to generating excessive loading forces, ramping effects, or wave deflection. The building official shall approve design plans for landscaping/aesthetic fill only after the applicant has provided an analysis by an engineer, architect, and/or soil scientist licensed in South Carolina which demonstrates that the following factors have been fully considered:

a.

Particle composition of fill material does not have a tendency for excessive natural compaction;

b.

Volume and distribution of fill will not cause wave deflection to adjacent properties; and

c.

Slope of fill will not cause wave run-up or ramping.

(5)

Manmade alteration of sand dunes and mangrove stands within zones VE and V on the Charleston County FIRM which would increase potential flood damage shall be prohibited.

(6)

The placement of new or replacement manufactured homes is prohibited.

(7)

A modular building (manufactured) may be installed in a V or VE-zone, providing the requirements in subsection (b) of this section are met, and the building meets the standards of the South Carolina Modular Building Construction Act (S.C. Code 1976, § 23-43-10 et seq.) as may be amended from time to time, which is incorporated herein by reference.

(8)

Preconstruction and as-built design and breakaway wall certifications, where applicable, shall be provided by registered professional engineers and/or architects licensed in South Carolina for new and substantially improved structures in V or VE flood zones on the Charleston County FIRM. These certificates shall also be provided for all lateral additions to structures in V or VE flood zones.

(9)

Enclosed areas below the lowest floor shall be the minimum necessary to allow for parking of vehicles, limited storage, and access to the primary occupancy (stairways and/or elevator).

(10)

Appurtenant features; defined as swimming pools, decks, gazebos, fences, and other features as determined by the building official as potentially causing an obstruction in the coastal high hazard area; must comply with the Federal Emergency Management Agency (FEMA) Technical Bulletin 5-93, Free of Obstruction Requirements, or any revisions thereto, incorporated herein by reference.

(c)

Specific standards for manufactured homes and recreational vehicles. (This section does not apply to modular building units).

(1)

New or replacement manufactured homes (e.g., those designed to meet HUD standards) shall not be placed within property located in zone V or VE on the Charleston County FIRM. Existing manufactured homes in V or VE zones may be permitted to remain as long as the structure complies with minimum health and safety standards and is anchored to resist flotation, collapse, lateral movement or debris impacts.

(2)

Permits shall be obtained for placement of manufactured homes or temporary construction trailers within zone A, AH, AO or AE on the Charleston County FHBM or FIRM. A temporary construction trailer may only be permitted to be on-site for fewer than 180 consecutive calendar days at a time, and must be fully ready for highway use, and shall be attached to the site only by quick-disconnect type utilities and security devices.

(3)

All manufactured homes permitted to be placed within zone AH or AE on the Charleston County FHBM or FIRM shall be installed using methods and practices which minimize flood damage, which include, but are not limited to, elevating the lowest floor of the manufactured home on a permanent foundation, as defined herein as a manufactured home permanent foundation, to or above one foot above the base flood elevation as indicated on the FIRM. For the purposes of this requirement, manufactured homes must be elevated and anchored to resist flotation, collapse or lateral movement. Methods of anchoring may include, but are not to be limited to, use of over-the-top or frame ties to ground anchors. This requirement is in addition to applicable state and local anchoring requirements for resisting wind forces.

(4)

All recreational vehicles, other than those parked at another permanent structure temporarily while not in use, placed or sited within zones AE, AH, AO, A, V and VE on the Charleston County FIRM must:

a.

Be on the site for fewer than 180 consecutive calendar days; and

b.

Be fully registered and ready for highway use. A recreational vehicle is ready for highway use if it is on its wheels or jacking system, is attached to the site only by quick-disconnect type utilities and security devices, and has no permanently attached additions. If the vehicle is to remain, it must be elevated in accordance with requirements for manufactured homes as provided in subsection (c) of this section.

(5)

Manufactured homes placed into AO flood zones shall comply with the elevation requirements indicated in subsection 26-42(1) of this chapter. The manufactured home must be securely anchored on a manufactured home permanent foundation as identified herein. Designs for manufactured home permanent foundations are subject to approval of the building official.

(6)

Manufactured homes placed into "A" flood zones without established base flood elevations shall comply with the elevation requirements indicated in subsection 26-44(2) of this chapter. The manufactured home must be securely anchored on a manufactured home permanent foundation as identified herein. Designs for manufactured home permanent foundations are subject to approval of the building official.

(d)

Regulatory floodways. Areas of special flood hazard established as regulatory floodways in the Charleston County Flood Insurance Rate Map (FIRM) and/or the Charleston County Flood Insurance Study, are the Charleston County designated floodways. Since the floodway is an extremely hazardous area due to the velocity of floodwaters which carry debris, potential projectiles and has erosion potential, the following provisions shall apply:

(1)

Prohibition of encroachments, including fill, new construction, substantial improvements and other development within the adopted regulatory floodway unless it has been demonstrated through hydrologic and hydraulic analyses performed in accordance with standard engineering practice in accordance with the Charleston County Flood Insurance Study or as otherwise deemed appropriate by FEMA or the building official, certified by a South Carolina licensed engineer, that the proposed encroachment would not result in any increase in flood levels within the community during the occurrence of the base flood discharges.

(2)

Encroachments may be permitted within the adopted regulatory floodway that would result in an increase in base flood elevations, provided that the county first applies for a conditional FIRM and floodway revision, fulfills the requirements for such revisions as established under the provisions of § 65.12 of 44 CFR and receives the approval of the federal insurance administrator.

(3)

Prohibition of the placement of manufactured homes, except in an existing manufactured home park or subdivision, and subject to all other requirements of this chapter and other laws, rules and regulations.

(4)

The area chosen for the regulatory floodway must be designed to carry the waters of the base flood, without increasing the water surface elevation of that flood more than one foot at any point. Studies performed to designate the regulatory floodway must be in accordance with accepted standard engineering practices, in accordance with the Charleston County Flood Insurance Study or as otherwise deemed appropriate by FEMA or the building official. In areas along the Chandler Bridge Creek previously unmapped on the Charleston County FIRM and other areas where floodways are determined to exist within the county through engineering analysis, but said floodways have not been previously studied and mapped for the NFIP, the regulatory floodway shall be designated using a 0.5 foot floodway surcharge standard.

(Ord. No. 2009-10-04, 9-28-2009)