FLOOD HAZARD PREVENTION AND CONTROL

Charleston, S.C., City Code ch. 27, art. II, div. 3

in effect

Charleston, S.C., City Code § 27-103 Definitions.

Sec. 27-103. - Definitions. Unless specifically defined in this section, words or phrases used in this division shall be interpreted so as to give them the meaning they have in common usage and to give this division its most reasonable application. Addition (to an existing building) means any walled and roofed expansion to the perimeter of a building in which the addition is connected by a common load-bearing wall other than a fire wall. Any wall and roofed addition which is connected by a fire wall or is separated by independent perimeter load-bearing walls is new construction. Appeal means a request for a review of the city's interpretation of any provision of this division or a request for a variance. Area of shallow flooding means a designated AO or VO zone on a community's flood insurance rate map (FIRM) with base flood depths from one (1) to three (3) feet where a clearly defined channel does not exist, where the path of flooding is unpredictable and indeterminate, and where velocity flow may be evident. Area of special flood hazard is the land in the flood plain within a community subject to a one (1) percent or greater chance of flooding in any given year. Base flood means the flood having a one (1) percent chance of being equaled or exceeded in any given year. Basement means that portion of a building having its floor sub-grade (below ground level) on all sides. Breakaway wall means a wall that is not part of the structural support of the building and is intended through its design and construction to collapse under specific lateral loading forces without causing damage to the elevated portion of the building or the supporting foundation system. Building means any structure built for support, shelter, or enclosure for any occupancy or storage. Coastal high hazard area means the area subject to high velocity waters caused by, but not limited to, hurricane wave wash or tsunamis. The area is designated on a FIRM as zone V1-30. Development means any manmade change to improved or unimproved real estate, including, but not limited to, buildings or other structure, permanent storage of equipment or material, mining, dredging, filling, grading, paving, excavation or drilling operations. Elevated building means a non-basement building built to have the lowest floor elevated above the ground level by means of fill, solid foundation perimeter walls, pilings, columns (posts and piers), shear walls, or breakaway walls. Elevation certificate means FEMA Form 81-31, February 13, 2006 or subsequent revisions, including FEMA Form 086-0-33 revised December 2019, used to show elevations of real property in relation to base flood elevations. Existing construction means any structure for which the "start of construction" commenced before April 9, 1971. Existing manufactured home park means a manufactured home park for which the construction of facilities for servicing the lots on which the manufactured homes are to be affixed (including at a minimum the installation of utilities, the construction of streets, and either final site grading or the pouring of concrete pads) is completed before April 9, 1971. Expansion to existing manufactured home park means the preparation of additional sites by the construction of facilities for servicing the lots on which the manufactured homes are to be affixed (including the installation of utilities, the construction of streets, and either final site grading or the pouring of concrete pads.) Fill or filling means placement of natural sands, dirt, soil or rock above the natural grade to raise the elevation of the ground, and may also include concrete, cement, soil cement, brick or similar material as approved on a case-by-case basis. Flood or flooding means a general and temporary condition of partial or complete inundation of normally dry land areas from: (1) The overflow of inland or tidal waters; (2) The unusual and rapid accumulation of runoff of surface waters from any source. Flood hazard boundary map (FHBM) means an official map of a community, issued by the Federal Emergency Management Agency, where the boundaries of the areas of special flood hazard have been defined as zone A. Flood insurance rate map (FIRM) means an official map of a community on which the Federal Emergency Management Agency has delineated both the areas of special flood hazard and the risk premium zones applicable to the community. Flood insurance study is the official report provided by the federal emergency management agency. The report contains flood profiles, as well as the flood boundary-floodway map and the water surface elevation of the base flood. Floodway means the channel of a river or other watercourse and the adjacent land areas that must be reserved in order to discharge the base flood without cumulatively increasing the water surface elevation more than one (1) foot. Floor means the top surface of an enclosed area in a building (including basement) i.e., top slab in concrete slab construction or top of wood flooring in wood frame construction. The term does not include the floor of a garage used solely for parking vehicles. Freeboard means a factor of safety usually expressed in feet above a base flood level for purposes of floodplain management. Functionally dependent facility means a facility which cannot be used for its intended purpose unless it is located or carried out in close proximity to water, such as a docking or port facility necessary for the loading and unloading of cargo or passengers, shipbuilding, ship repair, or seafood processing facilities. The term does not include long-term storage, manufacture, sales, or service facilities. Highest adjacent grade means the highest natural elevation of the ground surface, prior to construction, next to the proposed walls of a structure. Historic structure means any structure that is: (1) Listed individually in the National Register of Historic Places (a listing maintained by the Department of Interior) or preliminarily determined by the Secretary of the Interior as meeting the requirements for individual listing on the National Register; (2) Certified or preliminarily determined by the Secretary of the Interior as contributing to the historical significance of a registered historic district or a district preliminarily determined by the Secretary to qualify as a registered district; (3) Certified or preliminarily determined by the State Historic Preservation Office as contributing to the historical significance of a registered historic district or a district preliminarily determined by the Secretary of the Interior to be eligible for inclusion in the National Register. Lowest floor means the lowest floor of the lowest enclosed area (including basement). An unfinished or flood resistant enclosure, usable solely for parking of vehicles, building access, or storage in an area other than a basement area is not considered a building's lowest floor, provided that such enclosure is not built so as to render the structure in violation of the applicable non-elevation design requirements of this article. Mangrove stand means an assemblage of mangrove trees which is mostly low trees noted for a copious development of interlacing adventitious roots above the ground and which contain one (1) or more of the following species: black mangrove (Avicennia nitida); red mangrove (Rhizophora mangle); white mangrove (Languncularia racemosa); and buttonwood (Conocarpus erecta). Manufactured home means a structure, transportable in one (1) or more sections, which is built on a permanent chassis and designed to be used with or without a permanent foundation when connected to the required utilities. It also includes park trailers, travel trailers, and similar transportable structures placed on a site for one hundred eighty (180) consecutive days and intended to be improved property. Manufactured home park or subdivision means a parcel (or contiguous parcels) of land divided into two or more manufactured home lots for rent or sale. Market value means, for the purpose of making determinations of substantial damage or substantial improvement pursuant to this division: (1) The current market value of the building, as determined by the county's assessor's office; or (2) The appraised value of the building, as determined by an appraisal performed by an independent, licensed professional appraiser in accordance with the laws of the State of South Carolina within the past six (6) months from the date of determination. An appraised value shall supersede the county's market value in making final determinations of substantial damage or substantial improvement. Mean sea level means the average height of the sea for all stages of the tide. It is used as a reference for establishing various elevations within the flood plain. For purposes of this division, the term is synonymous with National Geodetic Vertical Datum (NGVD). National Geodetic Vertical Datum (NGVD) is a vertical control used as a reference for establishing varying elevations within the flood plain. New construction means structures for which the "start of construction" commenced on or after April 9, 1971. New manufactured home park means a manufactured home park for which the construction of facilities for servicing the lots on which the manufactured homes are to be affixed (including at a minimum, the installation of utilities, the construction of streets, and either final site grading or the pouring of concrete pads) is completed on or after April 9, 1971. Recreational vehicle means a vehicle which is: (1) Built on a single chassis; (2) Four hundred (400) square feet or less when measured at the largest horizontal projection; (3) Designed to be self-propelled or permanently towable by a light duty truck; and (4) Designed primarily not for use as a permanent dwelling but as temporary living quarters for recreational, camping, travel, or seasonal use. Sand dunes means naturally occurring accumulations of sand in ridges or mounds landward of the beach. Start of construction (for other than new construction or substantial improvements under the coastal barrier resources act (p. L. 97-348)), includes substantial improvement, and means the date the permit was issued, provided the actual start of construction, repair, reconstruction, or improvement was within one hundred eighty (180) days of the permit date. The actual start means the first placement of permanent construction of a building (including a manufactured home) on a site, such as the pouring of slabs or footings, installation of piles, construction of columns, or any work beyond the stage of excavation or the placement of a manufactured home on a foundation. Permanent construction does not include land preparation, such as clearing, grading and filling; nor does it include the installation of streets and/or walkways; nor does it include excavation for a basement, footings, piers or foundations or the erection of temporary forms; nor does it include the installation on the property of accessory buildings, such as garages or sheds not occupied as dwelling units or not part of the main building. For a substantial improvement, the actual start of construction means the first alteration of any wall, ceiling, floor, or other structural part of a building, whether or not that alteration affects the external dimensions of the building. Structure means a walled and roofed building that is principally above ground, a manufactured home, a gas or liquid storage tank, or other man-made facilities or infrastructures. Substantial damage means damage of any origin sustained by a structure whereby the cumulative cost of restoring and/or repairing the structure to its before damaged condition would equal or exceed fifty (50) percent of the market value of the structure before the damage occurred. The reconstruction and repairs are counted cumulatively for one (1) year. Substantial improvement means any repair, reconstruction, improvement or addition to an existing structure, where the cumulative cost counted for a one-year period equals or exceeds fifty (50) percent of the market value of the structure, either (1) before the improvement or repair is started, or (2) if the structure has been damaged and is being restored, before the damage occurred. For the purposes of this definition, "substantial improvement" is considered to occur when the first alteration of any wall, ceiling, floor. or other structural part of the building commences, whether or not that alteration affects the external dimensions of the structure. The term does not, however, include either (1) any project for improvement of a structure to comply with existing state or local health, sanitary, or safety code specifications which are solely necessary to assure safe living conditions, or (2) any alteration to a historic structure as defined in section 27-103 when such structure is judged by the chief building official to be safe and in the public interest of health, safety and welfare. Substantially improved existing manufactured home parks are where the repair, reconstruction, rehabilitation or improvement of the streets, utilities and pads equals or exceeds fifty (50) percent of the value of the streets, utilities and pads before the repair, reconstruction or improvement commenced. The reconstruction and repairs are counted cumulatively for one (1) year. Variance is a grant of relief to a person from the requirements of this division which permits construction in a manner otherwise prohibited by this division where specific enforcement would result in unnecessary hardship. Violation means the failure of a structure or other development to be fully compliant with these regulations. (Ord. No. 2008-58, § 2, 4-8-08; Ord. No. 2014-123, §§ 1—4, 9-9-14; Ord. No. 2018-131, § 1, 10-9-18; Ord. No. 2019-095, § 1, 10-8-19; Ord. No. 2020-147, § 1, 10-27-20; Ord. No. 2023-071, § 1, 4-11-23; Ord. No. 2024-097, § 1, 7-16-24)

Charleston, S.C., City Code § 27-104 Lands to which division applies.

Sec. 27-104. - Lands to which division applies. This division shall apply to all areas of special flood hazard within the jurisdiction of the city. (Ord. No. 2008-58, § 2, 4-8-08)

Charleston, S.C., City Code § 27-105 Establishment of areas of special flood hazard.

Sec. 27-105. - Establishment of areas of special flood hazard. Areas of special flood hazard in the city are identified in and established by the Federal Emergency Management Agency (FEMA) in its Flood Insurance Studies, Berkeley County study dated December 7, 2018 and Charleston County study dated January 29, 2021, with accompanying maps and other supporting data that are hereby adopted by reference and declared to be a part of this article. Upon annexation, any special flood hazard areas identified by FEMA in its Flood Insurance Study for the unincorporated areas of Berkeley County and Charleston County, with accompanying maps and other data, are adopted by reference and declared part of this article. (Ord. No. 2008-58, § 2, 4-8-08; Ord. No. 2018-131, § 2, 10-9-18; Ord. No. 2020-140, § 1, 10-13-20)

Charleston, S.C., City Code § 27-106 Compliance.

Sec. 27-106. - Compliance. No structure or land shall hereafter be located, extended, converted, or structurally altered without full compliance with the terms of this division and other applicable regulations. (Ord. No. 2008-58, § 2, 4-8-08)

Charleston, S.C., City Code § 27-107 Abrogation and greater restrictions.

Sec. 27-107. - Abrogation and greater restrictions. This division is not intended to repeal, abrogate or impair any existing easements, covenants or deed restrictions, except as specifically stated. In the event this division and another ordinance of the city should conflict or overlay, whichever ordinance imposes the more stringent restrictions shall prevail. (Ord. No. 2008-58, § 2, 4-8-08)

Charleston, S.C., City Code § 27-108 Interpretation.

Sec. 27-108. - Interpretation. In the interpretation and application of this division all provisions shall be: (1) Considered as minimum requirements; (2) Liberally construed in favor of the governing body; and (3) Deemed neither to limit nor repeal any other powers granted under state statutes. (Ord. No. 2008-58, § 2, 4-8-08)

Charleston, S.C., City Code § 27-109 Warning and disclaimer of liability.

Sec. 27-109. - Warning and disclaimer of liability. The degree of flooding protection required by this division is considered reasonable for regulatory purposes and is based on scientific and engineering consideration. Larger floods can and will occur on rare occasions. Flood heights may be increased by manmade or natural causes. This division does not imply that land outside the areas of special flood hazard or uses permitted within such areas will be free from flooding or flood damages. Nothing contained in this division shall create, or be deemed to create, any liability on the part of the city or by any officer or employee thereof for any flood damages that result from reliance on this division or any administrative decision lawfully made thereunder. (Ord. No. 2008-58, § 2, 4-8-08)

Charleston, S.C., City Code § 27-110 Annexations.

Sec. 27-110. - Annexations. Should further areas be annexed to the city, elevations existing as per the latest editions of the county FIRM maps, shall continue in force and effect at the time of such annexation. (Ord. No. 2008-58, § 2, 4-8-08)

Charleston, S.C., City Code § 27-111 Penalties.

Sec. 27-111. - Penalties. Violation of the provisions of this division or failure comply with any of its requirements, including violation of conditions and safeguards established in connection with grants of variance or special exceptions, shall constitute a misdemeanor. Any person who violates this division or fails to comply with any of its requirements shall, upon conviction thereof, be subject to punishment as provided in section 1-16 of this Code, and in addition shall pay all costs and expenses involved in the case. Nothing herein contained shall prevent the city from taking such other lawful action as is necessary to prevent or remedy any (Ord. No. 2008-58, § 2, 4-8-08)

Charleston, S.C., City Code § 27-112 Floodplain manager and chief building official to administer division.

Sec. 27-112. - Floodplain manager and chief building official to administer division. The city's floodplain manager and chief building official, or their duly designated agents, are hereby appointed to administer and implement the provisions of this division. (Ord. No. 2008-58, § 2, 4-8-08; Ord. No. 2023-071, § 2, 4-11-23)

Charleston, S.C., City Code § 27-113 Same—Duties and responsibilities.

Sec. 27-113. - Same—Duties and responsibilities. Duties of the chief building official or his designated agent shall include, but not limited to: (1) Reviewing all subdivision and development applications to assure that the requirements of this division have been satisfied; (2) Advising applicant that additional federal, state or local permits may be required, and if specific federal, state or local permits are known, requiring that copies of such permits be provided and maintained on file with the subdivision or development application; (3) Notifying adjacent communities and all appropriate federal, state and local government agencies, including the S.C. Water Resources Commission, prior to any alteration or relocation of a watercourse, and submitting evidence of such notification to the Federal Emergency Management Agency; (4) Assuring that maintenance is provided within the altered or relocation portion of such watercourse so that the flood-carrying capacity is not diminished; (5) In coastal high hazard areas obtaining certification from a registered professional engineer or architect that the structure is securely anchored to adequately anchored pilings or columns in order to withstand velocity waters and hurricane wave wash; (6) In coastal high hazard areas, reviewing plans for adequacy of breakaway walls in accordance with section 27-117(6)h. of this division; (7) When flood-proofing is utilized for a particular structure, obtaining certification from a registered professional engineer or architect that the structure has been flood-proofed in accordance with section 27-117 of this division; (8) Where interpretation is needed as to the exact location of boundaries of the areas of special flood hazard (for example, where there appears to be a conflict between a mapped boundary and actual field conditions) making the necessary interpretation. The person contesting the location of the boundary shall be given a reasonable opportunity to appeal the interpretation as provided in this division; (9) When base flood elevation data has not been provided in accordance with section 27-105 of this division, obtaining, reviewing and reasonably utilizing any base flood elevation data available from a federal, state or other source, in order to administer the provisions of Division 3 of this article; (10) Assuring that all records pertaining to the provisions of the ordinance from which this division derives are maintained by the city in the appropriate offices, and be open for public inspection. (Ord. No. 2008-58, § 2, 4-8-08)

Charleston, S.C., City Code § 27-114 Subdivision and development procedures.

Sec. 27-114. - Subdivision and development procedures. Application for a subdivision or development shall be made to the city prior to any development activities. Application shall include, but not be limited to, the following plans in duplicate drawn to scale showing the nature, locations, dimensions, and elevations of the area in question; existing or proposed structures, fill or storage of materials; drainage facilities, and the location of the foregoing. Specifically, the following information is required: (1) Elevation in relation to mean sea level of the proposed lowest floor; including basement, or the applicable structural members of all structures; (2) Elevation in relation to mean sea level to which any non-residential structure will be flood-proofed; (3) A certificate from a registered professional engineer or architect that the non-residential flood-proofed structure meets the flood-proofed criteria in section 27-117(2) of this division; (4) A description of the extent to which any watercourse will be altered or relocated as a result of proposed development; (5) A floor elevation or flood-proofing certification after the lowest floor is completed, or in instances where the structure is subject to the regulations applicable to coastal high hazard areas, after placement of the horizontal structural members of the lowest floor. Within twenty-one (21) calendar days the establishment of the lowest floor elevation, or flood-proofing by whatever construction means, or upon placement of the horizontal structural members of the lowest floor, whichever is applicable, it shall be the duty of the applicant to submit to the city a certification of the elevation of the lowest floor, flood-proofed elevation, or the elevation of the lowest portion of the horizontal structural members of the lowest floor, whichever is applicable, as built, in relation to mean sea level. Such certification shall be prepared by or under the direct supervision of a registered land surveyor or professional engineer and certified by same. When flood-proofing is utilized for a particular building, such certification shall be prepared by or under the direct supervision of a professional engineer or architect and certified by same. Any work done within the twenty-one-day calendar period and prior to submission of the certification shall be at the applicant's risk. The city shall review the floor elevation survey data submitted. Deficiencies detected by such review shall be corrected by the applicant immediately and prior to further progressive work being permitted to proceed. Failure to submit the survey or failure to make such corrections required hereby, shall be cause to issue a stop-work order for the project. (Ord. No. 2008-58, § 2, 4-8-08)

Charleston, S.C., City Code § 27-115 Variance procedures.

Sec. 27-115. - Variance procedures. (a) The building board of adjustments and appeals as established by the city council shall hear and decide appeals and requests for variances from the requirements of this division. (b) The building board of adjustments and appeals shall hear and decide appeals when it is alleged there is an error in any requirement, decision, or determination made by the city in the enforcement or administration of this division; provided, however, that, the person aggrieved requests a hearing before the building board of adjustment and appeals within ten (10) days of the determination made by the city from which appeal is sought. (c) Any person aggrieved by the decision of the building board of adjustment and appeals may appeal such decision to the appropriate court. (d) Variances may be issued for the repair or rehabilitation of historic structures (see definition) upon a determination the proposed repair or rehabilitation will not preclude the structure's continued designation as a historic structure character and design of the structure. (e) In passing upon applications for variances, the building board of adjustments and appeals shall consider all technical evaluations, all relevant factors, all standards specified in other sections of this division, and: (1) The danger that materials may be swept onto other lands to the injury of others; (2) The danger of life and property due to flooding or erosion damage; (3) The susceptibility of the proposed facility and its contents to flood damage and the effect of such damage on the individual owner; (4) The importance of the services provided by the proposed facility to the community; (5) The necessity to the facility of a waterfront location, where applicable; (6) The availability of alternative locations, not subject to flooding or erosion damage, for the proposed use; (7) The compatibility of the proposed use with existing and anticipated development; (8) The relationship of the proposed use to the comprehensive plan and flood plain management program for that area; (9) The safety of access to the property in times of flood for ordinary and emergency vehicles; (10) The expected heights, velocity, duration, rate of rise and sediment transport of the flood waters and the effects of wave action, if applicable, expected at the site; and (11) The costs of providing governmental services during and after flood conditions including maintenance and repair of public utilities and facilities such as sewer, gas, electrical and water systems, and street and bridges. (f) Upon consideration of the factors listed above and the purposes of this division, the building board of adjustments and appeals may grant such variances and attach such conditions to the granting of variances as it deems necessary to further the purposes of this division. (g) Variances shall not be issued within any designated floodway if any increase in flood levels during the base flood discharge would result. (h) Conditions for variances are as follows: (1) Variances shall only be issued upon determination that the variance is the minimum necessary considering the flood hazard, to afford relief; and in the instance of a historical building, a determination that the variance is the minimum necessary so as not to destroy the historic character and design of the building; and (2) Variances shall only be issued upon: a. A showing of good and sufficient cause; b. A determination that failure to grant the variance would result in exceptional hardship to the applicant; and c. A determination that the granting of a variance will not result in increased flood heights, additional threats to public safety, extraordinary public expense, create nuisance, cause fraud on or victimization of the public, or conflict with existing local laws or ordinances. (i) Any applicant to whom a variance is granted shall be given written notice specifying the difference between the base flood elevation and the elevation to which the building is to be built and stating that the cost of flood insurance will be commensurate with the increased risk resulting from the reduced lowest floor elevation. (j) The city shall maintain the records of all appeal actions and report any variances to the Federal Emergency Management Agency upon request.

Charleston, S.C., City Code § 27-116 General standards.

Sec. 27-116. - General standards. (a) In all areas of special flood hazard, the following provisions are required: (1) All new construction and substantial improvements shall be anchored to prevent floatation, collapse or lateral movement of the structure; (2) All new construction and substantial improvements shall be constructed with materials and utility equipment resistant to flood damage; be constructed by methods and practices that minimize flood damages; and be constructed with electrical, heating, ventilation, plumbing and air conditioning equipment (including ductwork), and other service facilities that are designed and/or located so as to prevent water from entering or accumulating within the components during conditions of the base flood plus applicable freeboard as set forth in section 27-117(1) and (2). (3) All new construction or substantial improvements shall be constructed by methods and practices that minimize flood damage; (4) All new and replacement water supply systems shall be designed to minimize or eliminate infiltration of flood waters into the system; (5) New and replacement sanitary systems shall be designed to minimize or eliminate infiltration of flood waters into the systems and discharges from the systems into flood waters; (6) On-site disposal systems shall be located and constructed to avoid impairment to them or contamination from them during flooding; (7) Any alteration, repair, reconstruction or improvements to a building which is not in compliance, shall be undertaken only if said non-conformity is not furthered, extended, or replaced. (8) All permit applications shall be reviewed to determine whether proposed building sites will be reasonably safe from flooding. (b) Any alteration, repair, reconstruction, or improvements to a structure which is in compliance with the provisions of this ordinance shall meet the requirements of "new construction" as contained in this division. (c) In order to address increasing flood levels, flood hazards, and the associated damage caused by the importation of fill, the following shall apply within the city's one-hundred-year regulatory floodplain: (1) Beginning January 1, 2024 (the "effective date"), the permitting of certain foundation types shall be prohibited for all new foundations for single-family dwellings, including attached single-family dwellings. (2) The most current version of Appendix B to the Federal Emergency Management Agency's National Flood Insurance Program (NFIP) Flood Insurance Manual dated October 2022 (the "appendix") is hereby incorporated by reference and shall govern acceptable foundation types, as may be supplemented and amended by the city's stormwater design standards manual. 1. The foundations depicted in Diagrams 1A, 1B, 2A, 2B, and 3 of the appendix are prohibited for detached single-family dwellings. 2. The foundations depicted in Diagrams 1A, 2A, 2B, and 3 of the appendix are prohibited for attached single-family dwellings. (3) The city's floodplain manager or his/her duly authorized agent shall review elevation certificates to ensure the proper type of foundation has been used pursuant to this section. (Ord. No. 2008-58, § 2, 4-8-08; Ord. No. 2018-131, § 3, 10-9-18; Ord. No. 2023-071, § 3, 4-11-23; Ord. No. 2024-097, § 2, 7-16-24)

Charleston, S.C., City Code § 27-117 Specific standards.

Sec. 27-117. - Specific standards. In all areas of special flood hazard where base flood elevation data has been provided, as set forth in section 27-105 or section 27-113(9), the following provisions are required: (1) Residential construction. New construction shall have the lowest floor, including basement, or the applicable structural member elevated at least two (2) feet above the level of base flood elevation prescribed for that zone. Substantial improvement of any residential structure shall have the lowest floor, including basement, or the applicable structural member elevated at least one (1) foot above the level of the base flood elevation prescribed for that zone. (2) Non-residential construction. New construction or substantial improvement of any commercial, industrial or other non-residential structure on or after April 9, 1971 shall either have the lowest floor, including basement, or the applicable structural member elevated at least two (2) feet above the level of the base flood elevation prescribed for that zone or, together with attendant utility and sanitary facilities be flood-proofed in accordance with the FEMA publication "Floodproofing Non-Residential Structures" (2013), so that all areas below the required elevation are watertight and 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. A registered professional engineer or architect shall certify that the standards of this subparagraph (2) are satisfied. Such certification shall be provided to the city as set forth in section 27-114(3) of this division. (3) Elevated buildings. New construction or substantial improvements of elevated buildings that include fully enclosed areas formed by foundation and other exterior walls below the base flood elevation shall be designed to preclude finished living space and designed to allow for the entry and exit of flood waters to automatically equalize hydrostatic flood forces on exterior walls. a. Designs for complying with this requirement must either be certified by a professional engineer or architect or meet the following minimum criteria: i. Provide a minimum of two (2) openings having a total net area of not less than one (1) square inch for every square foot of enclosed area subject to flooding; ii. The bottom of all openings shall be no higher than one (1) foot above grade; and iii. Openings may be equipped with screens, louvers, valves or other coverings or devices provided they permit the automatic flow of floodwater in both directions. b. Access to the enclosed area shall be the minimum necessary to allow for parking of vehicles (garage door) or limited storage of maintenance equipment used in connection with the premises (standard exterior door) or entry to the living area (stairway or elevator); and c. The interior portion of such enclosed area shall not be partitioned or finished into separate rooms. (4) Manufactured homes. Manufactured homes are subject to the following: a. No manufactured home shall be placed in a floodway or coastal high hazard area, except in an existing manufactured park or existing manufactured home subdivision. Manufactured homes placed in existing manufactured home subdivision in floodway or coastal high hazard areas shall be anchored as specified in subsection 27-117(4)b. and meet the elevation requirements in subsection 27-117(4)d.(i). b. All manufactured homes shall be anchored to resist floatation, collapse, or lateral movement by providing over-the-top and frame ties to ground anchors. Specific requirements shall be that: i. Over-the-top ties shall be provided at each end of the manufactured home, with one (1) additional tie per side at an intermediate location on manufactured homes of less fifty (50) feet and one (1) additional tie per side for manufactured homes of fifty (50) feet or more; ii. Frame ties shall be provided at each corner of the home with four (4) additional ties per side at intermediate points for manufactured home less than fifty (50) feet long and one (1) additional tie for manufactured homes of fifty (50) feet or longer; iii. All components of the anchoring system shall be capable of carrying a force of four thousand eight hundred (4,800) pounds; and iv. Any additions to the manufactured home shall be similarly anchored. c. For new manufactured home parks and subdivisions; for expansions to existing manufactured home parks and subdivisions; for existing parks and subdivisions where the repair, reconstruction or improvement of the streets, utilities and pads equal or exceed fifty (50) percent of value of the streets, utilities and pads before the repair, reconstruction or improvement has commenced; and, for manufactured homes not placed in a manufactured park or subdivision it is required that: i. Stands or lots be elevated on compacted fill or on pilings so that the lowest floor of new construction of the manufactured home will be at least two (2) feet above the base flood level; ii. Adequate surface drainage and access for a hauler be provided; and iii. In the instance of elevation on pilings: (i) Lots be large enough to permit steps; (ii) Piling foundations be placed in stable soil no more than ten (10) feet apart; and (iii) Reinforcement be provided for pilings more than six (6) feet above the ground level. d. All manufactured homes placed or substantially improved in an existing manufactured home park or subdivision must be elevated so that: i. The lowest floor of new construction of the manufactured home is elevated to at least two (2) feet above the level of the base flood elevation; ii. The manufactured home must be securely anchored to the adequately anchored foundation system to resist floatation, collapse and lateral movement. iii. In an existing manufactured home park or subdivision on which a manufactured home has incurred "substantial damage" as the result of a flood, any manufactured home placed or substantially improved must meet the standards of subsection 27-117(4)d.(i) and (ii) above. (5) Floodways. Located within the areas of special flood hazard established in section 27-105 are areas designated as floodways. Since the floodway is an extremely hazardous area due to the velocity of flood waters which carry debris, potential projectiles, and has erosion potential, the following provisions shall apply: a. No encroachments, including fill, or new construction or substantial improvements or any other developments shall be had until and unless certification (with supporting technical data) by a registered professional engineer is provided to the city engineer or his designated agent demonstrating that such activity shall not result in any increase in flood levels during occurrence of the base flood discharge; b. In the event the provisions of subparagraph (4)a. of this section are satisfied, all new construction and substantial improvements shall comply with all applicable flood hazard reduction provisions of this division (Division 3). c. There shall be no placement of any manufactured homes, except in an existing manufactured park or existing manufactured home subdivision. (6) High hazard areas—V or VE zones. 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: a. All new construction within zones V and VE on the Charleston FIRM shall be located landward of the reach of mean high tide. b. Provide that all new construction and substantial improvements in zones V and VE, if base flood elevation data is available on the Charleston FIRM, are elevated on pilings and columns so that: i. The bottom of the lowest horizontal structural member of the lowest floor (excluding the pilings or columns) of new construction is elevated to or above two (2) feet above the base flood level; and ii. 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 (6)b.i. and ii. of section 27-117 of the Code of Ordinances, of the City of Charleston, South Carolina. c. New construction and substantial improvements within zones V and VE on the Charleston FIRM have the space below the lowest floor either free of obstruction or constructed with non-supporting 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 twenty (20) pounds per square foot. Use of breakaway walls which exceed a design safe loading resistance of twenty (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: i. Breakaway wall collapse shall result from a water load less than that which would occur during the base flood; and ii. 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. d. There shall be no fill used as structural support. Non-compacted 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: i. Particle composition of fill material does not have a tendency for excessive natural compaction; ii. Volume and distribution of fill will not cause wave deflection to adjacent properties; and iii. Slope of fill will not cause wave run-up or ramping. e. Manmade alteration of sand dunes and mangrove stands within zones VE and V on the Charleston FIRM which would increase potential flood damage shall be prohibited. f. The placement of new or replacement manufactured homes is prohibited. g. A modular building (manufactured) may be installed in a V or VE zone, providing the requirements in this subsection 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. h. 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 FIRM. These certificates shall also be provided for all lateral additions to structures in V or VE flood zones. i. 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). j. 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. (7) Recreational vehicles. All recreational vehicles placed on sites must either: a. Be fully licensed and ready for highway use; or b. The recreational vehicle must meet all the requirements for new construction, including anchoring and elevation requirements of subsection 27-117(4), Manufactured homes. 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 structures. (Ord. No. 2008-58, § 2, 4-8-08; Ord. No. 2014-123, §§ 5, 6, 9-9-14; Ord. No. 2020-032, §§ 1—5, 3-10-20; Ord. No. 2021-008, § 1, 1-26-21)

Charleston, S.C., City Code § 27-118 Standards for streams without established base flood elevations and/or floodways.

Sec. 27-118. - Standards for streams without established base flood elevations and/or floodways. Located within the areas of special flood hazard established in section 21-117 of this division, where small streams exist but where no base flood data has been provided or where no floodways have been provided, the following provisions shall apply: (1) No encroachments, including fill materials or structures shall be located within a distance of the top of the stream bank equal to one (1) times the width of the stream at the top bank or twenty (20) feet on each side from top of bank, whichever is greater; unless certification by a registered professional engineer is provided demonstrating that such encroachments shall not result in any increase in flood level during the occurrence of the base flood discharge. (2) New construction for substantial improvements of structures shall be elevated or flood-proofed in accordance with elevations established in accordance with subsection 27-113(9) of this division. (3) In the event that the city has been unable to determine flood elevation data to fulfill subsection 27-118(2), a lowest floor elevation requirement of five (5) feet above highest adjacent grade must be required. (Ord. No. 2008-58, § 2, 4-8-08)

Charleston, S.C., City Code § 27-119 Standards for subdivision proposals.

Sec. 27-119. - Standards for subdivision proposals. (a) All subdivision proposals shall be consistent with the need to minimize flood damage, shall be reviewed to determine whether proposed building sites will be reasonably safe from flooding, and are subject to all applicable standards in these regulations. (b) All subdivision proposals shall have public utilities and facilities such as sewer, gas, electrical and water systems located and construction to minimize flood damage. (c) All subdivision proposals shall have all street and storm drainage designed and provided in accordance with standards adopted by the city so as to minimize exposure and damage thereto by flooding. (d) Base flood elevation data shall be provided for subdivision proposals and other proposed developments which are greater than the lesser of fifty (50) lots or five (5) acres. (Ord. No. 2008-58, § 2, 4-8-08; Ord. No. 2018-131, § 4, 10-9-18)

Charleston, S.C., City Code § 27-120 Standards for areas of shallow flooding (AO zone).

Sec. 27-120. - Standards for areas of shallow flooding (AO zone). Located within the areas of special flood hazard established in section 27-105 of this division are areas designed as areas of shallow flooding. These areas have special flood hazards associated with base flood depths of one (1) to three (3) feet where a clearly defined channel does not exist and where the path of flooding is unpredictable and indeterminate; therefore, the following provisions shall apply: (1) All new construction and substantial improvements of residential shall have the lowest floor, including basement, elevated to one (1) foot above the depth number specified on the flood insurance rate map, in feet, the highest adjacent grade. If no depth number is specified, the lowest floor, including basement, shall be elevated, at least three (3) feet above the highest adjacent grade. (2) All new construction and substantial improvements of non-residential structures shall: a. Have the lowest floor, including basement, elevated to one (1) foot above the depth number specified on the flood insurance rate map, in feet, above the highest adjacent grade. If no depth number is specified, the lowest floor, including basement, shall be elevated at least three (3) feet above the highest adjacent grade; or b. Together with attendant utility and sanitary facilities be completely flood-proofed to or above that level in accordance with the FEMA publication "Flood-Proofing Non-Residential Structures" (1987), so that any space below that level 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. A registered professional engineer or architect shall certify that the standards of this subsection are satisfied. Such certification shall be provided to the city as set forth in section 27-114(3) of this division. (3) All structures on slopes must have drainage paths around them to guide water away from the structures. (Ord. No. 2008-58, § 2, 4-8-08; Ord. No. 2014-123, § 7, 9-9-14; Ord. No. 2018-131, § 5, 10-9-18)

Charleston, S.C., City Code § 27-121 Standards for streams with established base flood elevations but without floodways.

Sec. 27-121. - Standards for streams with established base flood elevations but without floodways. Along rivers and streams where base flood elevation (BFE) data are provided but no floodway is identified for a special flood hazard area on the FIRM or in the FIS, no encroachments including fill, new construction, substantial improvements, or other development shall be permitted unless certification with supporting technical data by a registered professional engineer is provided demonstrating that the cumulative effect of the proposed development, when combined with all other existing and anticipated development, will not increase the water surface elevation of the base flood more than one foot at any point within the city. (Ord. No. 2018-131, § 6, 10-9-18)

Source: City of Charleston, South Carolina, Code of Ordinances and Zoning Ordinance (Municode Library, library.municode.com)URL: https://library.municode.com/sc/charleston/codes/code_of_ordinances?nodeId=CICO_CH27STMAFLCO_ARTIISTFAFLHADAPRCO_DIV3FLHAPRCOFetched: 11/7/2026