§ 150.41  SPECIFIC STANDARDS.
   In addition to the provisions of § 150.40, the following provisions are required:
   (A)   Residential construction. New construction and substantial improvement of any residential structure (including manufactured homes) shall have the reference level, including basement, elevated no lower than the regulatory flood protection elevation, as defined in § 150.05 of this chapter.
   (B)   Non-residential construction. New construction and substantial improvement of any commercial, industrial, or other non-residential structure shall have the reference level, including basement, elevated no lower than the RFPE, as defined in § 150.05. Structures located in Zones A, AE, AH, AO, A99 Shaded X and X may be floodproofed to the RFPE in lieu of elevation provided that all areas of the structure, together with attendant utility and sanitary facilities, below the RFPE are watertight 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. For AO Zones, the floodproofing elevation shall be in accordance with § 150.43. A registered professional engineer or architect shall certify that the floodproofing standards of this subsection are satisfied. Such certification shall be provided to the Floodplain Administrator as set forth in § 150.26(C), along with the operational plan and the inspection and maintenance plan.
   (C)   Manufactured homes.
      (1)   New and replacement manufactured homes shall be elevated so that the reference level of the manufactured home is no lower than the RFPE, as defined in § 150.05.
      (2)   Manufactured homes shall be securely anchored to an adequately anchored foundation to resist flotation, collapse, and lateral movement, either by certified engineered foundation system, or in accordance with the most current edition of the State of North Carolina Regulations for Manufactured Homes adopted by the Commissioner of Insurance pursuant to G.S. 143-143.15. Additionally, when the elevation would be met by an elevation of the chassis 36 inches or less above the grade at the site, the chassis shall be supported by reinforced piers or engineered foundation. When the elevation of the chassis is above 36 inches in height, an engineering certification is required.
      (3)   All enclosures or skirting below the lowest floor shall meet the requirements of § 150.41(D).
      (4)   An evacuation plan must be developed for 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 Floodplain Administrator and the local Emergency Management Coordinator.
   (D)   Elevated buildings. Fully enclosed area, of new construction and substantially improved structures, which is below the lowest floor or below the lowest horizontal structural member in VE zones:
      (1)   Shall not be designed or used for human habitation, but shall only be used for parking of vehicles, building access, or limited storage of maintenance equipment used in connection with the premises. Access to the enclosed area shall be the minimum necessary to allow for parking of vehicles (garage door) or limited storage of maintenance equipment (standard exterior door), or entry to the living area (stairway or elevator). The interior portion of such enclosed area shall not be finished or partitioned into separate rooms, except to enclose storage areas;
      (2)   Shall be constructed entirely of flood resistant materials at least to the regulatory flood protection elevation; and
      (3)   Shall include, in Zones A, AE, AH, AO, A99, Shaded X and X, flood openings to automatically equalize hydrostatic flood forces on walls by allowing for the entry and exit of floodwaters. To meet this requirement, the openings must either be certified by a professional engineer or architect or meet or exceed the following minimum design criteria:
         (a)   A minimum of two flood openings on different sides of each enclosed area subject to flooding;
         (b)   The total net area of all flood openings must be at least one square inch for each square foot of enclosed area subject to flooding or a minimum of one engineered inch for each square foot of enclosed area for an engineered opening;
         (c)   If a building has more than one enclosed area, each enclosed area must have flood openings to allow floodwaters to automatically enter and exit consistent with § 150.41(D)(3)(a) above;
         (d)   The bottom of all required flood openings shall be no higher than one foot above the higher of the interior or exterior adjacent grade;
         (e)   Flood openings may be equipped with screens, louvers, or other coverings or devices, provided they permit the automatic flow of floodwaters in both directions; and
         (f)   Enclosures made of flexible skirting are not considered enclosures for regulatory purposes, and, therefore, do not require flood openings. Masonry or wood underpinning, regardless of structural status, is considered an enclosure and requires flood openings as outlined above.
      (4)   In CHHA shall either be free of obstruction or constructed with breakaway walls, open wood latticework or insect screening, provided they are not part of the structural support of the building and are designed so as to breakaway, under abnormally high tides or wave action without causing damage to the elevated portion of the building or supporting foundation system or otherwise jeopardizing the structural integrity of the building. The following design specifications shall be met:
         (a)   Material shall consist of open wood or plastic lattice or insect screening; or
         (b)   Breakaway walls shall contain the required amount and size of flood vents consistent with § 150.41(D)(3)(a) and (b) and meet the following design specifications:
            1.   Design safe loading resistance shall be not less than ten nor more than 20 pounds per square foot; or
            2.   Breakaway walls that exceed a design safe loading resistance of 20 pounds per square foot (either by design or when so required by State or local codes) shall be certified by a registered professional engineer or architect that the breakaway wall will collapse from a water load less than that which would occur during the base flood event, and the elevated portion of the building and supporting foundation 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). The water loading values used shall be those associated with the base flood. The wind loading values used shall be those required by the North Carolina State Building Code.
      (5)   Property owners shall be required to execute and record a non-conversion agreement prior to issuance of a building permit declaring that the area below the lowest floor shall not be improved, finished or otherwise converted to habitable space. This agreement shall be recorded with the Dare County Register of Deeds and shall transfer with the property in perpetuity. The Town of Duck will have the right to inspect the enclosed area. Such inspection should be coordinated with the property owner.
      (6)   Release of restrictive covenant. If a property which is bound by a non-conversion agreement is modified to remove enclosed areas below RFPE, then the owner may request release of restrictive covenant after staff inspection and submittal of confirming documentation.
   (E)   Additions/improvements/conversions.
      (1)   Standards in all flood zones (AE, AO, VE, Shaded X, and X).
         (a)   Additions and/or improvements to pre-FIRM structures when the addition and/or improvements in combination with any interior modifications to the existing structure are:
            1.   Not a substantial improvement, the addition and/or improvements must be designed to minimize flood damages and must not be any more non-conforming than the existing structure.
            2.   A substantial improvement, with modifications/rehabilitations/improvements to the existing structure or the common wall is structurally modified more than installing a doorway, both the existing structure and the addition must comply with the standards for new construction.
         (b)   Additions to pre-FIRM or post-FIRM structures that are a substantial improvement with no modifications/rehabilitations/improvements to the existing structure other than a standard door in the common wall, shall require only the addition to comply with the standards for new construction.
         (c)   Additions and/or improvements to post-FIRM structures when the addition and/or improvements in combination with any interior modifications to the existing structure are:
            1.   Not a substantial improvement, the addition and/or improvements only must comply with the standards for new construction consistent with the code and requirements for the original structure.
            2.   A substantial improvement, both the existing structure and the addition and/or improvements must comply with the standards for new construction.
         (d)   A substantial improvement must comply with the standards for new construction. For each building or structure, the one-year period begins on the date of the first improvement or repair of that building or structure subsequent to the effective date of this ordinance. If the structure has sustained substantial damage, any repairs are considered substantial improvement regardless of the actual repair work performed. The requirement does not, however, include either:
            1.   Any project for improvement of a building required to correct existing health, sanitary or safety code violations identified by the code enforcement official and that are the minimum necessary to assume safe living conditions.
            2.   Any alteration of a historic structure provided that the alteration will not preclude the structure's continued designation as a historic structure.
         (e)   Areas in existing structures may be converted to conditioned, temperature-controlled space provided the use is limited to parking, storage and access. Property owner will be required to record a non-conversion agreement consistent with § 150.41(D)(5).
      (2)   Additional standards in Shaded X and X Zones. Remodeling or renovations of existing structures with the reference level located below the current applicable RFPE that do not increase the footprint or temperature-controlled area of the structure may be authorized at the existing reference level or higher. Reconstruction of damage to the structure with no increase in footprint may be authorized at the existing reference level or higher.
   (F)   Recreational vehicles. Recreational vehicles shall either:
      (1)   Meet the following standards for temporary placement:
         (a)   Be on site for fewer than 180 consecutive days; or
         (b)   Be fully licensed 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 has no permanently attached additions.)
      (2)   Permanent placement. Recreational vehicles located in the Town of Duck that do not meet the limitations of temporary placement shall meet all the requirements for new construction.
   (G)   Temporary non-residential structures. Prior to the issuance of a floodplain development permit for a temporary structure, the applicant must submit to the Floodplain Administrator a plan for the removal of such structure(s) in the event of a hurricane, flash flood or other type of flood warning notification. The following information shall be submitted in writing to the Floodplain Administrator for review and written approval:
      (1)   A specified time period for which the temporary use will be permitted. Time specified may not exceed three months, renewable up to one year;
      (2)   The name, address, and phone number of the individual responsible for the removal of the temporary structure;
      (3)   The time frame prior to the event at which a structure will be removed (i.e., minimum of 72 hours before landfall of a hurricane or immediately upon flood warning notification);
      (4)   A copy of the contract or other suitable instrument with the entity responsible for physical removal of the structure; and
      (5)   Designation, accompanied by documentation, of a location outside the special flood hazard area, to which the temporary structure will be moved.
   (H)   Accessory structures. The following criteria shall be met:
      (1)   Accessory structures shall not be used for human habitation (including working, sleeping, living, cooking or restroom areas)
      (2)   Accessory structures may have conditioned, temperature-controlled space provided the use is limited to parking or storage. The property owner will be required to record a non-conversion agreement consistent with § 150.41(D)(5). Electrical, heating, ventilation, plumbing, air conditioning, and other service equipment associated with an accessory structure shall be located at or above the RFPE.
      (3)   Accessory structures shall be designed to have low flood damage potential;
      (4)   Accessory structures shall be constructed and placed on the building site so as to offer the minimum resistance to the flow of floodwaters;
      (5)   Accessory structures shall be firmly anchored in accordance with the provisions of § 150.40(A);
      (6)   Accessory structures, regardless of the size or cost, shall not be placed below elevated buildings in the CHHA;
      (7)   All service facilities such as electrical shall be installed in accordance with the provisions of § 150.40(D); and
      (8)   Flood openings to facilitate automatic equalization of hydrostatic flood forces shall be provided below Regulatory Flood Protection Elevation in conformance with the provisions of § 150.41(D)(3). The Floodplain Administrator shall certify installation of required flood openings in compliance with these provisions.
      (9)   Secondary structures located on the same parcel in addition to a principal use structure which feature conditioned, temperature-controlled areas elevated above the regulatory flood protection elevation shall be constructed consistent with §§ 150.20 and 150.21.
   (I)   Tanks. Gas and liquid storage tanks shall meet the following criteria:
      (1)   Underground tanks. Underground tanks in flood hazard areas shall be anchored to prevent flotation, collapse or lateral movement resulting from hydrodynamic and hydrostatic loads during conditions of the design flood, including the effects of buoyancy assuming the tank is empty;
      (2)   Above-ground tanks, elevated. Above-ground tanks in flood hazard areas may be elevated to or above the Regulatory Flood Protection Elevation on a supporting structure that is designed to prevent flotation, collapse or lateral movement during conditions of the design flood. Tank-supporting structures shall meet the foundation requirements of the applicable flood hazard area;
      (3)   Above-ground tanks, not elevated. Above ground tanks that do not meet the elevation requirements of §§ 150.41(B) and (I)(2) shall not be permitted in the CHHA. Above-ground tanks in flood hazard areas may be located below the regulatory flood protection elevation provided the tanks are designed, constructed, installed, and anchored to resist all flood-related and other loads, including the effects of buoyancy and lateral movement, during conditions of the design flood and without release of contents in the floodwaters or infiltration by floodwaters into the tanks. Tanks shall be designed, constructed, installed, and anchored to resist the potential buoyant and other flood forces acting on an empty tank during design flood conditions.
      (4)   Tank inlets and vents. Tank inlets, fill openings, outlets and vents shall be located at or above the regulatory flood protection elevation or fitted with covers designed to prevent lateral movement, the inflow of floodwater or outflow of the contents of the tanks during conditions of the design flood.
(Ord. 20-01, passed 5-20-2020)