The requirements of this section shall:
A. Apply in flood hazard areas identified as coastal high hazard areas
(V Zones) and Coastal A Zones.
B. Apply to all development, new construction, and substantial improvements
(including repair of substantial damage).
Exception: In Coastal A Zones, the requirements of Article
IV shall apply to substantial improvements (including repair of substantial damage).
New structures and substantial improvement (including repair of substantial damage) of existing structures shall comply with this section and Article
II.
A. Design certification. The application shall include a certification prepared by a licensed designer that the design and construction methods meet the requirements of Subsections
B,
C and
D below, and the building code.
B. 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 design shall include the
effects of decreased resistance capacity from soil scouring.
(2) Slabs, pools, pool decks and walkways shall be elevated in compliance
with this chapter or 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.
C. Elevation requirements.
(1) The bottom of the lowest horizontal structural member that supports
the lowest floor shall be above the flood protection elevation.
(2) Basement floors 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 below.
D. Enclosures below the lowest floor.
(1) Enclosures below the lowest floor shall be used solely for vehicle
parking, building access or limited storage.
(2) Enclosures below the lowest floor shall be less than 300 square feet
in area (exterior measurement to outside of finish materials).
(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 structure.
(4) No electrical, mechanical or plumbing system components shall be
below the lowest floor except where necessary for connection to off-site
utilities. 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 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 licensed designer's certification
that:
(a)
The walls and partitions below the lowest floor will function
as breakaway walls.
(b)
The elevated portion of the building and supporting foundation
system have been designed to withstand the effects of wind and flood
loads simultaneously acting 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, walls below the lowest floor shall have flood openings that meet the requirements of §
70-28, Residential structures, Subsection
B(3).
Note: NFIP Technical Bulletin No. 5, "Free-of-Obstruction Requirements,"
provides helpful guidance in applying these requirements.
A. Decks and patios. In addition to all other requirements of the building
code, decks and patios shall be located, designed, and constructed
to comply with the following:
(1) A deck structurally connected to a structure shall have the bottom
of its lowest horizontal structural member above the flood protection
elevation. Any supporting members that extend below the flood protection
elevation shall comply with the foundation requirements applicable
to the structure. The structure shall be designed to accommodate any
increased loads caused by the deck.
(2) A deck or patio 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 with vertical thickness of more than 12 inches or
constructed with more than the minimum fill necessary for site drainage
shall provide an analysis by a licensed designer demonstrating no
harmful diversion of floodwaters or wave run-up and wave reflection
that would increase damage to elevated structures.
(4) A deck or patio may be approved without analysis of the impact on
diversion of floodwaters, wave run-up or wave reflection, provided
that the deck or patio:
(a)
Has a vertical thickness of 12 inches or less; and
(b)
Is at natural grade or on fill material that is similar to local
soils; and
(c)
Uses fill in the minimum amount necessary for site drainage.
B. Other development. Other development activities shall be permitted
only if located outside the footprint of, and not structurally connected
to, structures. The permit application for such development must provide
an analysis performed by a licensed designer, demonstrating no harmful
diversion of floodwaters or wave run-up 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