International Building Code 1612.1
General.Within flood hazard areas as established in Section
1612.3, all new construction of buildings, structures and
portions of buildings and structures, including substantial
improvement and restoration of substantial damage to buildings
and structures, shall be designed and constructed to resist the
effects of flood hazards and flood loads. For buildings that are
located in more than one flood hazard area, the provisions associated
with the most restrictive flood hazard area shall apply.
International Building Code 1612.2
Definitions. The following words and terms shall, for
the purposes of this section, have the meanings shown herein.
BASE FLOOD. The flood having a 1-percent chance of being
equaled or exceeded in any given year.
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BASE FLOOD ELEVATION. The elevation of the base
flood, including wave height, relative to the National Geodetic
Vertical Datum (NGVD), North American Vertical Datum
(NAVD) or other datum specified on the Flood Insurance Rate
BASEMENT. The portion of a building having its floor
subgrade (below ground level) on all sides.
DESIGN FLOOD. The flood associated with the greater of
the following two areas:
1. Area with a flood plain subject to a 1-percent or greater
chance of flooding in any year; or
2. Area designated as a flood hazard area on a community’s
flood hazard map, or otherwise legally designated.
DESIGN FLOOD ELEVATION. The elevation of the
“design flood,” including wave height, relative to the datum
specified on the community’s legally designated flood hazard
map. In areas designated as Zone AO, the design flood elevation
shall be the elevation of the highest existing grade of the
building’s perimeter plus the depth number (in feet) specified
on the flood hazard map. In areas designated as ZoneAOwhere
a depth number is not specified on the map, the depth number
shall be taken as being equal to 2 feet (610 mm).
DRY FLOODPROOFING. A combination of design modifications
that results in a building or structure, including the
attendant utility and sanitary facilities, being water tight with
walls substantially impermeable to the passage of water and
with structural components having the capacity to resist loads
as identified in ASCE 7.
EXISTING CONSTRUCTION. Any buildings and structures
for which the “start of construction” commenced before
the effective date of the community’s first flood plain management
code, ordinance or standard. “Existing construction” is
also referred to as “existing structures.”
EXISTING STRUCTURE. See “Existing construction.”
FLOOD or FLOODING. A general and temporary condition
of partial or complete inundation of normally dry land from:
1. The overflow of inland or tidal waters.
2. The unusual and rapid accumulation or runoff of surface
waters from any source.
FLOOD DAMAGE-RESISTANT MATERIALS. Any construction
material capable of withstanding direct and prolonged
contact with floodwaters without sustaining any
damage that requires more than cosmetic repair.
FLOOD HAZARD AREA. The greater of the following two
1. The area within a flood plain subject to a 1-percent or
greater chance of flooding in any year.
2. The area designated as a flood hazard area on a community’s
flood hazard map, or otherwise legally designated.
FLOOD HAZARD AREA SUBJECT TO HIGH VELOCITYWAVE
ACTION. Area within the flood hazard area that
is subject to high velocity wave action, and shown on a Flood
Insurance Rate Map (FIRM) or other flood hazard map as Zone
V, VO, VE or V1-30.
FLOOD INSURANCE RATE MAP (FIRM). An official
map of a community on which the Federal Emergency Management
Agency (FEMA) has delineated both the special flood
hazard areas and the risk premium zones applicable to the community.
FLOOD INSURANCE STUDY. The official report provided
by the Federal Emergency Management Agency containing the
Flood Insurance Rate Map (FIRM), the Flood Boundary and
Floodway Map (FBFM), thewater surface elevation of the base
flood and supporting technical data.
FLOODWAY. The channel of the river, creek or other watercourse
and the adjacent land areas that must be reserved in
order to discharge the base flood without cumulatively increasing
thewater surface elevation more than a designated height.
LOWEST FLOOR. The floor of the lowest enclosed area,
including basement, but excluding any unfinished or
flood-resistant enclosure, usable solely for vehicle parking,
building access or limited storage provided that such enclosure
is not built so as to render the structure in violation of this section.
SPECIAL FLOOD HAZARD AREA. The land area subject
to flood hazards and shown on a Flood Insurance Rate Map or
other flood hazard map as Zone A, AE, A1-30, A99, AR, AO,
AH, V, VO, VE or V1-30.
START OF CONSTRUCTION. The date of permit issuance
for new construction and substantial improvements to existing
structures, provided the actual start of construction, repair,
reconstruction, rehabilitation, addition, placement or other
improvement is within 180 days after the date of issuance. The
actual start of construction means the first placement of permanent
construction of a building (including a manufactured
home) on a site, such as the pouring of a slab or footings, installation
of pilings or construction of columns.
Permanent construction does not include land preparation
(such as clearing, excavation, grading or filling), the installation
of streets or walkways, excavation for a basement, footings,
piers or foundations, the erection of temporary forms or
the installation 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.
SUBSTANTIAL DAMAGE. Damage of any origin sustained
by a structure whereby the cost of restoring the structure to its
before-damaged conditionwould equal or exceed 50 percent of
the market value of the structure before the damage occurred.
SUBSTANTIAL IMPROVEMENT. Any repair, reconstruction,
rehabilitation, addition or improvement of a building or
structure, the cost of which equals or exceeds 50 percent of the
market value of the structure before the improvement or repair
is started. If the structure has sustained substantial damage, any
repairs are considered substantial improvement regardless of
the actual repair work performed. The term does not, however,
1. Any project for improvement of a building required to
correct existing health, sanitary or safety code violations
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identified by the building official and that are the minimum
necessary to assure 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.
International Building Code 1612.3
Establishment of flood hazard areas. To establish
flood hazard areas, the governing body shall adopt a flood hazard
map and supporting data. The flood hazard map shall
include, at a minimum, areas of special flood hazard as identified
by the Federal Emergency Management Agency in an
engineering report entitled “The Flood Insurance Study for
[INSERT NAME OF JURISDICTION],” dated [INSERT DATE OF ISSUANCE],
as amended or revised with the accompanying Flood
InsuranceRateMap (FIRM) and FloodBoundary and Floodway
Map (FBFM) and related supporting data along with any revisions
thereto. The adopted flood hazardmap and supporting data
are hereby adopted by reference and declared to be part of this
International Building Code 1612.4
Design and construction. The design and construction
of buildings and structures located in flood hazard areas,
including flood hazard areas subject to high velocity wave
action, shall be in accordance with ASCE 24.
International Building Code 1612.5
Flood hazard documentation. The following documentation
shall be prepared and sealed by a registered design
professional and submitted to the building official:
1. For construction in flood hazard areas not subject to
high-velocity wave action:
1.1. The elevation of the lowest floor, including the
basement, as required by the lowest floor elevation
inspection in Section 109.3.3.
1.2. For fully enclosed areas below the design flood
elevation where provisions to allow for the automatic
entry and exit of floodwaters do not meet
the minimum requirements in Section 126.96.36.199 of
ASCE 24, construction documents shall include
a statement that the design will provide for equalization
of hydrostatic flood forces in accordance
with Section 188.8.131.52 of ASCE 24.
1.3. For dry floodproofed nonresidential buildings,
construction documents shall include a statement
that the dry floodproofing is designed in accordance
with ASCE 24.
2. For construction in flood hazard areas subject to
high-velocity wave action:
2.1. The elevation of the bottom of the lowest horizontal
structural member as required by the lowest
floor elevation inspection in Section 109.3.3.
2.2. Construction documents shall include a statement
that the building is designed in accordance
with ASCE 24, including that the pile or column
foundation and building or structure to be
attached thereto is designed to be anchored to
resist flotation, collapse and lateral movement
due to the effects of wind and flood loads acting
simultaneously on all building components, and
other load requirements of Chapter 16.
2.3. For breakaway walls designed to resist a nominal
load of less than 10 psf (0.48 kN/m2) or more than
20 psf (0.96 kN/m2), construction documents
shall include a statement that the breakaway wall
is designed in accordance with ASCE 24.