In addition to the general requirements of Article IV, the requirements of this section shall:
A. 
Apply in flood hazard areas that are identified as coastal high-hazard areas (V Zones) and Coastal A Zones (if delineated).
B. 
Apply to all development, new construction, substantial improvements (including repair of substantial damage), and placement, replacement, and substantial improvement (including repair of substantial damage) of manufactured homes. Exception: In Coastal A Zones, the requirements of Article V shall apply to substantial improvements (including repair of substantial damage), and substantial improvement of manufactured homes (including repair of substantial damage) and replacement of manufactured homes.
[Note: See "Coastal Construction Manual" (FEMA P-5S).]
A. 
The placement of structural fill for the purpose of elevating buildings is prohibited.
B. 
Buildings shall be located landward of the reach of mean high tide.
C. 
Minor grading, and the placement of minor quantities of fill, shall be permitted for landscaping and for drainage purposes under and around buildings and for support of parking slabs, pool decks, patios and walkways.
D. 
Site preparations shall not alter sand dunes unless an engineering analysis demonstrates that the potential for flood damage is not increased.
New structures and substantial improvement (including repair of substantial damage) of existing structures shall comply with the applicable requirements of Article IV and the requirements of this section.
A. 
Foundations.
(1) 
Structures shall be supported on pilings or columns and shall be adequately anchored to such pilings or columns. Pilings shall have adequate soil penetrations to resist the combined wave and wind loads (lateral and uplift). Water loading values used shall be those associated with the base flood. Wind loading values shall be those required by applicable building codes. Pile embedment shall include consideration of decreased resistance capacity caused by scour of soil strata surrounding the piling.
(2) 
Slabs, pools, pool decks and walkways shall be located and constructed to be structurally independent of structures and their foundations to prevent transfer of flood loads to the structures during conditions of flooding, scour, or erosion from wave-velocity flow conditions, and shall be designed to minimize debris impacts to adjacent properties and public infrastructure.
B. 
Elevation requirements.
(1) 
The bottom of the lowest horizontal structural member that supports the lowest floor shall be located at or above the flood protection elevation.
(2) 
Basement floors that are below grade on all sides are prohibited.
(3) 
The space below an elevated building shall either be free-of-obstruction or, if enclosed by walls, shall meet the requirements of Subsection D. [NOTE: See NFIP Technical Bulletin No. 5, "Free-of-Obstruction Requirements."]
C. 
Certification of design. As required in § 149-15A(14), the applicant shall include in the application a certification prepared by a licensed professional engineer or a licensed architect that the design and methods of construction to be used meet the requirements of Subsections A, B and D and the building code.
D. 
Enclosures below the lowest floor.
(1) 
Enclosures below the lowest floor shall be used solely for parking of vehicles, building access or limited storage.
(2) 
Enclosures below the lowest floor shall be less than 299 square feet in area (exterior measurement).
(3) 
Walls and partitions are permitted below the elevated floor, provided that such walls and partitions are designed to break away under flood loads and are not part of the structural support of the building or structure. [NOTE: See NFIP Technical Bulletin No. 9, "Design and Construction Guidance for Breakaway Walls."]
(4) 
Electrical, mechanical, and plumbing system components shall not be mounted on or penetrate through walls that are designed to break away under flood loads.
(5) 
Walls intended to break away under flood loads shall be constructed with insect screening or open lattice, or shall be designed to break away or collapse without causing collapse, displacement or other structural damage to the elevated portion of the building or supporting foundation system. Such walls, framing and connections shall have a design safe loading resistance of not less than 10 pounds per square foot and no more than 20 pounds per square foot; or
(6) 
Where wind loading values of the building code exceed 20 pounds per square foot, the applicant shall submit a certification prepared and sealed by a licensed professional engineer or licensed architect that:
(a) 
The walls and partitions below the lowest floor have been designed to collapse from a water load less than that which would occur during the base flood.
(b) 
The elevated portion of the building and supporting foundation system have been designed to withstand the effects of wind and flood 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 the building code.
(c) 
In Coastal A Zones, in addition to the requirements of this section, walls below the lowest floor shall have flood openings that meet the requirements of § 149-34C(3).
A. 
A horizontal addition proposed for a building or structure that was constructed after the date specified in § 149-1 shall comply with the applicable requirements of Article IV and this section.
B. 
For horizontal additions, whether structurally connected or not structurally connected, to the base building:
(1) 
If the addition combined with other proposed repairs, alterations, or modifications of the base building constitutes substantial improvement, the base building and the addition shall comply with the applicable requirements of Article IV and this section.
(2) 
If the addition constitutes substantial improvement, the base building and the addition shall comply with all of the applicable requirements of Article IV and this section. [NOTE: The base building is required to comply. Otherwise it is an obstruction that does not comply with the free-of-obstruction requirement that applies to the elevated addition. See § 149-40B(3).]
C. 
A horizontal addition to a building or structure that is not substantial improvement is not required to comply with this section.
A. 
Accessory structures shall be limited to not more than 300 square feet in total floor area, unless a variance is granted authorizing not more than 900 square feet.
B. 
Accessory structures shall comply with the elevation requirements and other requirements of § 149-40 or, if not elevated, shall:
(1) 
Be usable only for parking of vehicles or limited storage;
(2) 
Be constructed with flood-damage-resistant materials below the base flood elevation;
(3) 
Be constructed and placed to offer the minimum resistance to the flow of floodwaters;
(4) 
Be anchored to prevent flotation;
(5) 
Have electrical service and mechanical equipment elevated to or above the base flood elevation; and
(6) 
If larger than 100 square feet in size, have walls that meet the requirements of § 149-40D(3) through (6), as applicable for the flood zone; and if located in coastal a zones, walls shall have flood openings that meet the requirements of § 149-34C(3).
[NOTE: See NFIP Technical Bulletin No. 5, "Free-of-Obstruction Requirements."]
A. 
Decks and patios. In addition to the requirements of the building code or the residential code, decks and patios shall be located, designed, and constructed in compliance with the following:
(1) 
A deck that is structurally attached to a building or structure shall have the bottom of the lowest horizontal structural member at or above the flood protection elevation and any supporting members that extend below the design flood elevation shall comply with the foundation requirements that apply to the building or structure, which shall be designed to accommodate any increased loads resulting from the attached deck.
(2) 
A deck or patio that is located below the flood protection elevation shall be structurally independent from structures and their foundation systems, and shall be designed and constructed either to remain intact and in place during base flood conditions or to break apart into small pieces that will not cause structural damage to adjacent elevated structures.
(3) 
A deck or patio that has a vertical thickness of more than 12 inches or that is constructed with more than the minimum amount of fill that is necessary for site drainage shall not be approved unless an analysis demonstrates no harmful diversion of floodwaters or wave runup and wave reflection that would increase damage to adjacent elevated structures.
(4) 
A deck or patio that has a vertical thickness of 12 inches or less and that is at natural grade or on fill material that is similar to and compatible with local soils and is the minimum amount necessary for site drainage may be approved without requiring analysis of the impact on diversion of floodwaters or wave runup and wave reflection.
B. 
Other development. Other development activities shall be permitted only if located outside the footprint of, and not structurally attached to, structures, and only if an analysis demonstrates no harmful diversion of floodwaters or wave runup and wave reflection onto adjacent elevated structures. Other development includes but is not limited to:
(1) 
Bulkheads, seawalls, retaining walls, revetments, and similar erosion control structures;
(2) 
Solid fences, privacy walls, and fences prone to trapping debris, unless designed and constructed to fail under base flood conditions; and
(3) 
Mounded septic systems.