About this appendix: Appendix G is intended to provide the additional flood-plain management and administrative requirements of the National Flood Insurance Program (NFIP) that are not included in the code. Communities that adopt the International Building Code® and Appendix G will meet the minimum requirements of NFIP as set forth in Title 44 of the Code of Federal Regulations.
Code development reminder: Code change proposals to this appendix will be considered by the IBC—Structural Code Development Committee during the 2019 (Group B) Code Development Cycle. See explanation on page iv.
The purpose of this appendix is to promote the public health, safety and general welfare and to minimize public and private losses due to flood conditions in specific flood hazard areas through the establishment of comprehensive regulations for management of flood hazard areas designed to:
- Prevent unnecessary disruption of commerce, access and public service during times of flooding.
- Manage the alteration of natural flood plains, stream channels and shorelines.
- Manage filling, grading, dredging and other development that may increase flood damage or erosion potential.
- Prevent or regulate the construction of flood barriers that will divert floodwaters or that can increase flood hazards.
- Contribute to improved construction techniques in the flood plain.
This appendix, in conjunction with this code, provides minimum requirements for development located in flood hazard areas, including:
- The subdivision of land.
- Site improvements and installation of utilities.
- Placement and replacement of manufactured homes.
- Placement of recreational vehicles.
- New construction and repair, reconstruction, rehabilitation or additions to new construction.
- Substantial improvement of existing buildings and structures, including restoration after damage.
- Installation of tanks.
- Temporary structures.
- Temporary or permanent storage, utility and miscellaneous Group U buildings and structures.
- Certain building work exempt from permit under Section 105.2 and other buildings and development activities.
All applications for permits must comply with the following:
- The building official shall review all permit applications to determine whether proposed development is located in flood hazard areas established in Section G102.2.
- Where a proposed development site is in a flood hazard area, all development to which this appendix is applicable as specified in Section G102.1 shall be designed and constructed with methods, practices and materials that minimize flood damage and that are in accordance with this code and ASCE 24.
- Obtain, review and reasonably utilize data available from a federal, state or other source.
- Determine the design flood elevation in accordance with accepted hydrologic and hydraulic engineering techniques. Such analyses shall be performed and sealed by a registered design professional. Studies, analyses and computations shall be submitted in sufficient detail to allow review and approval by the building official. The accuracy of data submitted for such determination shall be the responsibility of the applicant.
The applicant shall file an application in writing on a form furnished by the building official. Such application shall:
- Identify and describe the development to be covered by the permit.
- Describe the land on which the proposed development is to be conducted by legal description, street address or similar description that will readily identify and definitely locate the site.
- Include a site plan showing the delineation of flood hazard areas, floodway boundaries, flood zones, design flood elevations, ground elevations, proposed fill and excavation and drainage patterns and facilities.
- Include in subdivision proposals and other proposed developments with more than 50 lots or larger than 5 acres (20 234 m2), base flood elevation data in accordance with Section 1612.3.1 if such data are not identified for the flood hazard areas established in Section G102.2.
- Indicate the use and occupancy for which the proposed development is intended.
- Be accompanied by construction documents, grading and filling plans and other information deemed appropriate by the building official.
- State the valuation of the proposed work.
- Be signed by the applicant or the applicant's authorized agent.
- Listed or preliminarily determined to be eligible for listing in the National Register of Historic Places.
- Determined by the Secretary of the U.S. Department of Interior as contributing to the historical significance of a registered historic district or a district preliminarily determined to qualify as an historic district.
- Designated as historic under a state or local historic preservation program that is approved by the Department of Interior.
In reviewing applications for variances, the board of appeals shall consider all technical evaluations, all relevant factors, all other portions of this appendix and the following:
- The danger that materials and debris may be swept onto other lands resulting in further injury or damage.
- The danger to life and property due to flooding or erosion damage.
- The susceptibility of the proposed development, including contents, to flood damage and the effect of such damage on current and future owners.
- The importance of the services provided by the proposed development to the community.
- The availability of alternate locations for the proposed development that are not subject to flooding or erosion.
- The compatibility of the proposed development with existing and anticipated development.
- The relationship of the proposed development to the comprehensive plan and flood plain management program for that area.
- The safety of access to the property in times of flood for ordinary and emergency vehicles.
- The expected heights, velocity, duration, rate of rise and debris and sediment transport of the floodwaters and the effects of wave action, if applicable, expected at the site.
- The costs of providing governmental services during and after flood conditions including maintenance and repair of public utilities and facilities such as sewer, gas, electrical and water systems, streets and bridges.
Variances shall only be issued by the board of appeals where all of the following criteria are met:
- A technical showing of good and sufficient cause that the unique characteristics of the size, configuration or topography of the site renders the elevation standards inappropriate.
- A determination that failure to grant the variance would result in exceptional hardship by rendering the lot undevelopable.
- A determination that the granting of a variance will not result in increased flood heights, additional threats to public safety, extraordinary public expense, nor create nuisances, cause fraud on or victimization of the public or conflict with existing local laws or ordinances.
- A determination that the variance is the minimum necessary, considering the flood hazard, to afford relief.
- Notification to the applicant in writing over the signature of the building official that the issuance of a variance to construct a structure below the base flood level will result in increased premium rates for flood insurance up to amounts as high as $25 for $100 of insurance coverage, and that such construction below the base flood level increases risks to life and property.
DEVELOPMENT. Any man-made change to improved or unimproved real estate, including but not limited to, buildings or other structures, temporary structures, temporary or permanent storage of materials, mining, dredging, filling, grading, paving, excavations, operations and other land-disturbing activities.
FUNCTIONALLY DEPENDENT FACILITY. A facility that cannot be used for its intended purpose unless it is located or carried out in close proximity to water, such as a docking or port facility necessary for the loading or unloading of cargo or passengers, shipbuilding or ship repair. The term does not include long-term storage, manufacture, sales or service facilities.
MANUFACTURED HOME. A structure that is transportable in one or more sections, built on a permanent chassis, designed for use with or without a permanent foundation when attached to the required utilities, and constructed to the Federal Mobile Home Construction and Safety Standards and rules and regulations promulgated by the U.S. Department of Housing and Urban Development. The term also includes mobile homes, park trailers, travel trailers and similar transportable structures that are placed on a site for 180 consecutive days or longer.
MANUFACTURED HOME PARK OR SUBDIVISION. A parcel (or contiguous parcels) of land divided into two or more manufactured home lots for rent or sale.
RECREATIONAL VEHICLE. A vehicle that is built on a single chassis, 400 square feet (37.16 m2) or less when measured at the largest horizontal projection, designed to be selfpropelled or permanently towable by a light-duty truck, and designed primarily not for use as a permanent dwelling but as temporary living quarters for recreational, camping, travel or seasonal 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 security devices and has no permanently attached additions.
VARIANCE. A grant of relief from the requirements of this section that permits construction in a manner otherwise prohibited by this section where specific enforcement would result in unnecessary hardship.
VIOLATION. A development that is not fully compliant with this appendix or Section 1612, as applicable.
Any subdivision proposal, including proposals for manufactured home parks and subdivisions, or other proposed new development in a flood hazard area shall be reviewed to verify all of the following:
- Such proposals are consistent with the need to minimize flood damage.
- Public utilities and facilities, such as sewer, gas, electric and water systems, are located and constructed to minimize or eliminate flood damage.
- Adequate drainage is provided to reduce exposure to flood hazards.
The following requirements shall apply in the case of any proposed subdivision, including proposals for manufactured home parks and subdivisions, any portion of which lies within a flood hazard area:
- The flood hazard area, including floodways, coastal high-hazard areas and coastal A zones, as appropriate, shall be delineated on tentative and final subdivision plats.
- Design flood elevations shall be shown on tentative and final subdivision plats.
- Residential building lots shall be provided with adequate buildable area outside the floodway.
- The design criteria for utilities and facilities set forth in this appendix and appropriate International Codes shall be met.
Mechanical equipment and outside appliances shall be elevated to or above the design flood elevation.
Exception: Where such equipment and appliances are designed and installed to prevent water from entering or accumulating within their components and the systems are constructed to resist hydrostatic and hydrodynamic loads and stresses, including the effects of buoyancy, during the occurrence of flooding up to the elevation required by Section R322 of the International Residential Code, the systems and equipment shall be permitted to be located below the elevation required by Section R322 of the International Residential Code. Electrical wiring systems shall be permitted below the design flood elevation provided that they conform to the provisions of NFPA 70.
Mechanical, plumbing and electrical systems, including plumbing fixtures, shall be elevated to or above the design flood elevation.
Exception: Electrical systems, equipment and components; heating, ventilating, air conditioning and plumbing appliances; plumbing fixtures, duct systems and other service equipment shall be permitted to be located below the design flood elevation provided that they are designed and installed to prevent water from entering or accumulating within the components and to resist hydrostatic and hydrodynamic loads and stresses, including the effects of buoyancy, during the occurrence of flooding to the design flood elevation in compliance with the flood-resistant construction requirements of this code. Electrical wiring systems shall be permitted to be located below the design flood elevation provided that they conform to the provisions of NFPA 70.
|ASCE 24—13||Flood Resistant Design and Construction||G103.1, G401.3, G401.4, G701.1, G801.1, G801.5, G801.6, G801.7, G901.1, G1001.4|
|HUD 24 CFR Part 3280 (2008)||Manufactured Home Construction and Safety Standards||G201|
|IBC—18||International Building Code||G102.2, G1001.1, G1001.3|
|IRC—18||International Residential Code||G501.2, G501.4, G501.5|
|NFPA 70—17||National Electrical Code||G501.4, G1001.6|