Sec. 21-20. Permitted, conditional, special exceptions and prohibited uses.
   A.   Permitted uses in the RS-District.
      (1)   One single family detached dwelling per lot, designed for and occupied exclusively as a residence by one family, either owner or renter occupied.
      (2)   Publicly owned facility or land.
      (3)   Non-commercial horticulture or agriculture.
   B.   Conditional uses in the RS-District.
      (1)    Accessory use in compliance with the provisions in Article XV.
      (2)   Customary home occupation established under the provisions in Article XV.
      (3)   Modular building unit as a single family detached dwelling provided it meets all requirements of the South Carolina Modular Building Construction Act being S.C. Code § 23-43-10 et seq.
      (4)   Lots containing two occupied dwellings:
         (a)   Documentation that since August 1, 1977, both dwellings have been continually occupied by a family member or under a long-term rental agreement;
         (b)   If one or both buildings remain unoccupied or not rented for a period of more than one (1) year, then the right to occupy one of the two buildings shall be terminated; and,
         (c)   If rented, a current rental agreement must be on file with the Town.
      (5)   Electrical and water meters:
         (a)   Only one electrical and/or water meter shall be allowed per residentially zoned lot.
         (b)   An owner shall be permitted to maintain additional meters if the additional meters were lawfully installed on a legally authorized dwelling for which a Certificate of Occupancy was duly issued at the time of the original ratification of the Zoning Ordinance in 1977; provided, such additional meter’s use has not been discontinued as evidenced by a lack of use for a period of at least one (1) year. In the event any additional meter is removed, no additional electrical and/or water meter shall be reinstalled in place thereof.
      (6)   Attached additions that do not share heated space with the principal dwelling provided
         (a)   No kitchen facilities are allowed, and
         (b)   Deed restrictions are placed on the property prohibiting rental as a separate dwelling, and
         (c)   Any attached addition with an established connection to the principal building, shall be located under one roof and retain a permanent floor constructed above grade. The length to width ratio of the proposed connection may not exceed a two to one (2:1) dimension ratio, with a minimum width of four (4) feet, a maximum length of twenty (20) feet, and shall be visually and architecturally integrated with the existing principal building; said structures, as conditional uses, being reviewed and aesthetically approved by the Design Review Board. (9/17/2013)
   C.   Special exceptions in the RS-District.
      (1)   Definition and approval.
         (a)   A use permitted in a zoning district that possesses characteristics that require certain controls in order to ensure compatibility with other uses in the district within which they are proposed for location and therefore shall be approved by the Board of Zoning Appeals.
         (b)   In addition to requiring the approval of the Board of Zoning Appeals, special exceptions in the RS-Single Family District are subject to specific conditions that are enumerated by type of use.
      (2)   Historic structure used as accessory dwelling unit. As an incentive to preserve historic structures and avoid their demolition, a second dwelling may be constructed on the same lot as an historic structure, and the historic structure may be used as an accessory dwelling, when all of the following conditions are met:
         (a)   Prior use shall have been used as a dwelling; and
         (b)   The size of the historic structure is less than twelve hundred (1200) square feet of heated space at the time of its designation as historic and is listed as an historic property as described in Section 21-94 Historic Property Designation Criteria; provided, however, that a structure reduced to less than 1200 square feet of heated space after its designation as historic may qualify for special exception approval for an additional dwelling on the same lot, but only if the Design Review Board review determines and specifies in findings, that: (5-15-07)
            a.   Special circumstances justify such reduction in square feet based on the criteria listed in Section 21-94D. (1-8); and (5-15-07)
            b.   The portions removed from the historic property were added less than fifty (50) years ago and/or obscured an earlier feature of the historic house which contributed substantially to the most important elements of its historic character, definition and integrity. Examples of the latter instance include the removal of an enclosure of a porch when the open porch had been characteristic of a particular type of Island structure, or removal of an addition which covered a distinctive feature of the structure that is shared by neighboring structures. (5-15-07)
            These provisions shall supersede any inconsistent provisions contained in other portions of Chapter 21 relating to the use of historic structures as accessory dwellings, including but not limited to Section 21-140. (5-15-07)
         (c)   In the event the historic structure does not meet current FEMA elevation requirements, the Design Review Board finds that bringing it into compliance would significantly impair the historic and architectural character of the structure; and
         (d)   In the event the historic structure meets current FEMA elevations requirements, the Design Review Board finds that there is no feasible design solution for an addition to the historic structure that would not significantly impair the historic and architectural character of the structure; and
         (e)   No separate utility service meters shall be permitted; and
         (f)   The bottom elevation of the new second structure’s first story floor joists shall be no greater than two (2) feet above the FEMA base flood elevation; and
         (g)   The Design Review Board must find that the height, scale, mass and placement of the second structure are appropriate to and compatible with the lot on which it is sited, the character of the historic structure and surrounding neighborhood. When necessary to achieve such appropriateness and compatibility, the Design Review Board may impose stricter limits on height, setback, size and coverage than those of the zoning standards; and
         (h)   Permission to build a second structure and to use the historic structure as an accessory dwelling is approved as a special exception by the Board of Zoning Appeals; and
         (i)   The following conditions as covenants running with the property shall be placed on the real estate title to the property by the owner of the lot by recording deed restrictions for the benefit of the Town of Sullivan’s Island on the owner(s) title and recording the same in the RMC office for Charleston County before a building permit is issued:
            (i)   The lot shall remain in single ownership; more specifically, regardless of the type of ownership every owner, member, partner, shareholder, or unit owner, must have the same percentage of ownership in the historic structure as in any additional structure(s); and
            (ii)   Every owner, member, partner, shareholder or unit owner must have the same amount of control over the use of the historic structure as over any additional structure(s); and
         (j)   Discretionary increases by the Design Review Board in principal building coverage, impervious surface coverage and square footage may not be granted to properties with a second structure.
         (k)   If the historic structure used as an accessory dwelling is damaged or destroyed, by natural disaster, civil strife or uncontrollable accident, by more than fifty percent (50%) of its assessed value based on the most recent property assessment, the structure may be repaired in accordance with its preexisting footprint, square footage, setbacks, and lot coverage. The Zoning Administrator shall rely on all credible information provided by the owner and/or available from the Town, to establish the damaged or destroyed structure’s pre-existing condition and lot location. A Certificate of Zoning Compliance and a Building Permit shall be obtained within twelve (12) months of the date of occurrence of such damage, and once issued, construction shall be diligently pursued and completed within two (2) years from the date of the occurrence of such damage. If FEMA regulations require the structure’s foundation to be elevated over fifty percent (50%) above its original elevation, the Design Review Board shall determine whether or not the reconstruction shall be required to meet the current Zoning Ordinance’s Setback requirements.
(Ord. 2018-07, passed 11-20-2018)
         (l)   The historic structure used as an accessory dwelling may be used as a long-term rental, but only so long as the principal structure is occupied by an owner of the property as primary residence and a current business license is held on the same property. Primary residence is defined as a dwelling where the owner or owners reside on a permanent basis and are assessed at the four percent (4%) assessment rate on their ad valorem property tax.
      (3)   Religious institution:
         (a)   Limited to one building per lot;
         (b)   Housed in a permanent building;
         (c)   Located on a lot not less than one-half (1/2) acre in area;
         (d)   Provides off-street location for picking-up and dropping-off adults and children;
         (e)   Provides adequate off-street parking, in accordance with Article XVI; and,
         (f)   Meets the Setback and lot coverage standards of the RS District.
      (4)   Public utility substation:
         (a)   Shall be fenced or enclosed to provide adequate safety with a plan approved by the Design Review Board;
         (b)   Does not provide office, operational functions or storage of vehicles or equipment beyond the required utility equipment to provide service at that location;
         (c)   Meets the Setback and lot coverage standards of the RS District.
      (5)   Conservation Easement Uses as defined in Section 21-203 Definitions.
         (a)   Purpose. It is the purpose of this section to recognize that all properties on Sullivan’s Island are part of a dynamic and ever-changing barrier island environment, vulnerable to erosion and catastrophic flooding events. Whereas all Island properties in close proximity to marshes, beaches and waterways are predisposed to erosion, loss of critical dune vegetation and structural damage during large storm events, the Town recognizes a need to develop innovative methods to incentivize the protection of open space, preserve view-shed corridors, and reduce the intensity of residential land uses. (11-17-15)
         (b)   Applicability. As an incentive to preserving environmentally sensitive properties zoned for residential purposes (RS District), property owners (grantor) may establish certain recreational uses and structures as part of a permanent conservation easement. These non-residential uses must include retaining or protecting natural or open-space values of real property, assuring its availability for noncommercial agricultural, forestal, recreational, or open-space use, protecting natural resources, maintaining or enhancing air or water quality, or preserving the historical, architectural or archeological aspects of real property. The Board of Zoning Appeals may authorize a conservation easement structure or use upon a finding that establishment of the use or structure will not be of a substantial detriment to an adjacent property or to the public good, and the granting of the use or structure will not harm the character of the district. (11-17-15)
         (c)   General Conditions.
            i.   Prior to issuance of a building permit the property owner must remove any previously constructed structures, driveways, recreational structures (pools, courts, sheds, etc.), pervious or impervious surfaces, and utilities associated with any previous residential or commercial development. (11-17-15)
            ii.   Use of the property for commercial or rental activity is expressly prohibited. (11-17-15)
            iii.   The use of the property shall be limited to owners and guests, not to exceed twenty-four (24) individuals at any given time. (11-17-15)
         (d)   Structures.
            i.   Size. One open-air structure (gazebo, cabana, pergola, arbor, or other open-air structure) not exceeding in square footage, five (5) percent of the parcel’s total upland area, or two hundred fifty (250) square feet, whichever is less. A potential increase of two (2) percent will be allowed to the structure’s square footage, with a 450 square foot maximum, if an existing residential structure has been removed from the parcel. (11-17-15)
            ii.   Height. Structure may not exceed a maximum height of ten (10) feet from the natural grade as measured from the center point of the proposed structure to the highest point of the roof. Height may be extended to thirteen (13) feet where the majority pitch of the structure’s roof is 4/12 or more. An increase in height may be allowed if the roof’s lowest horizontal structural member must be constructed above the Base Flood Elevation (BFE), however, under no circumstances may roof height exceed 3 feet over BFE. (11-17-15)
            iii.   Storage. The structure may contain no more than thirty (30) percent of the total allowed square footage as enclosed area designated for storage space. Enclosed area may include one shower stall and must be constructed with breakaway walls and designed in accordance with FEMA National Flood Insurance Program (NFIP) regulations and the Town of Sullivan’s Island Flood Prevention Ordinance. (11-17-15)
            iv.   No rooftop seating or use will be permitted. (11-17-15)
            v.   Structure may not contain sewer facilities or portable sewage collection or disposal devices. Following the removal of any existing sewer facilities, all the requirements of Town Code of Ordinance Chapters 50 and 51 shall be met (Water and Sewer Utility Regulations.) (11-17-15)
            vi.   Lighting. There shall be no exterior site or structural lighting. Interior lighting shall be designed and arranged to prevent glare on adjoining properties, adjacent Recreation and Conservation Area Districts, or any other area of the beach or marsh. (11-17-15)
            vii.   Building setback. Fifteen (15) foot setbacks are required from all property lines and must meet the approval of the South Carolina Department of Health and Environmental Control and Ocean and Coastal Resource Management (DHEC-OCRM) agencies prior to submitting an application for Special Exception consideration. The Board of Zoning Appeals may adjust the setback requirement in instances where severe erosion, historic structures, natural topography, or trees and vegetation poses an unnecessary hardship for meeting the required fifteen (15) foot setback. (11-17-15)
         (e)   Parking.
            i.   A maximum of two vehicles will be permitted on the subject property. (11-17-15)
            ii.   All parking surfaces must remain in its natural state or turf grass. No additional impervious or engineered surfaces will be permitted. (11-17-15)
            iii.   No temporary outdoor storage of vehicles, recreational vehicles, boats, camping facilities, temporary event structures, machinery, or beach equipment shall be permitted except during the daytime use of the property. (11-17-15)
         (f)   Open Storage. No permanent outdoor storage permitted. Outdoor storage is defined as the keeping within an unroofed and unenclosed area any foods, material, merchandise, or vehicles. (11-17-15)
         (g)   Neighborhood Compatibility. The Design Review Board must review all proposed conservation easement structures to ensure design compatibility with the surrounding neighborhood and ensure an environmentally sensitive, low scale design, which maximizes public view corridors. No structure height, square footage, or massing increases will be permitted by the Design Review Board. (11-17-15)
         (h)   Legal Instrument for Permanent Protection. The instrument of permanent protection shall be a permanent conservation easement recorded by the Charleston County Register of Mesne Conveyance Office (RMC), concurrent with the issuance of a Town of Sullivan’s Island Building Permit and land disturbance permit: (11-17-15)
            i.   A land trust or similar conservation-oriented non-profit organization (grantee) with legal authority to accept such easements. The organization shall be bona fide and in perpetual existence and the conveyance instruments shall contain an appropriate provision for retransfer in the event the organization becomes unable to carry out its functions, and; (11-17-15)
            ii.   The Town shall receive a copy of the Annual Conservation Easement Inspection Report, and; (11-17-15)
            iii.   The Town of Sullivan’s Island shall reserve a third-party right of enforcement in the conservation easement agreement. (11-17-15)
   D.   Prohibited uses in the RS-District.
      (1)   Residences that contain less than one thousand (1,000) square feet of enclosed living area;
      (2)   Erosion control structures.
      (3)   Guest bedroom or dwelling unit for a person or persons not meeting the Zoning Ordinance’s definition of “family” or not lawfully occupied in accordance with (6) below .
      (4)   Mobile homes or manufactured homes.
      (5)   Non-commercial horticulture or agriculture that includes poultry, bovine or swine or any other type of non-traditional animal or reptile.
      (6)   Vacation Rentals other than those permitted in accordance with ARTICLE XIII.