This lesson should take approximately 15-20 minutes to complete.

This unit discusses the typical community floodplain management and building code environment. The role of local officials in a retrofitting project, the various tenets of the National Flood Insurance Program (NFIP), and the compatibility of items covered in the International Building Code (IBC) series are discussed.

Define the National Flood Insurance Program (NFIP)
Describe applicable flood hazard information in an NFIP participating community
Describe the community regulations and permitting process
Explain the influence of National Model Building Codes and consensus standards on flood-resistant design and construction

Regulatory Requirements

The components that make up a typical community floodplain management and building code environment include:

The NFIP
Local officials and community regulations
Compatibility of model building codes with the NFIP
Application of consensus standards

Flood Hazard Definitions

National Flood Insurance Program (NFIP): A voluntary program that operates through a partnership between the federal government and individual communities. The three components of the NFIP are flood insurance, floodplain mapping, and flood hazard mapping.

Base Flood Elevation (BFE): The water surface elevation resulting from the base, or 100-year flood, which is defined as the flood having a 1-percent chance of being equaled or exceeded in any given year.

Flood Insurance Study (FIS): Provides a narrative of the community's flood history and sources of flooding, as well as detailed information on the hydraulics and hydrology in the community.

Flood Hazard Definitions (cont.)

Flood Insurance Rate Map (FIRM): Official map of an NFIP community that delineates the SFHAs and the insurance risk premium zones applicable to the community.

Special Flood Hazard Area (SFHA): Area subject to inundation by the base flood.

Flood Insurance Rate Maps

Figure 2-1. Typical DFIRM for riverine flooding

Flood Insurance Rate Maps (Continued)

Figure 2-2. Typical DFIRM for coastal flooding showing the Limit of Moderate Wave Action

Even the latest FIRMs and FISs may be based on limited data, so the local floodplain manager should always be contacted for the latest information

Fig 2-2 flood insurance rate map-refer to table

IS 0280 flood insurance rate maps fig 2-2 table

Flood Insurance Studies (1 of 3)

Flood Insurance Studies-detailed engineering study, flood insurance study, flood insurance rate map

FIRMs are based on the information provided in an FIS. An FIS is based on detailed engineering studies. The FIS contains information such as:

Detailed information on the hydrology and hydraulics of the community's floodplain
Narrative of the community's flood history and sources of flooding
Riverine floodplains: discharges and flood profiles
Coastal floodplains: stillwater elevations and wave height transects
Can be obtained through floodplain manager or online at FEMA Map Service Center http://www.msc.fema.gov

Flood Insurance Studies (2 of 3)

fig 2-3 flood insurance studies --cross section of reverine floodplain

Figure 2-3. Typical riverine floodplain cross section

Riverine Floodplains

FISs describe how the flood hazard information was developed for a community (history and methodology)
FISs include:

Floodways
Discharges/ water surface elevations for 10-, 50-, 100-, and 500-year floods
Velocities
Flood profiles

Flood Insurance Studies (3 of 3)

Coastal Floodplains

FISs Include: storm surge stillwater elevations for 10-, 50-, 100-, and 500-year floods
FIS wave analyses include beach and dune erosion estimates

fig 2-4 flood insurance studies-wave height transect showing LiMWA, MoWA, and MiWA

Figure 2-4. Wave height transect showing LiMWA, MoWA, and MiWA

Floodplain Management Regulations

To participate in the NFIP, communities must regulate development in floodplains in accordance with the NFIP

Must ensure two basic criteria are met before issuing a permit for development:

All new construction, substantial improvements, and repair of substantial damage will be protected from damage by the base flood
New floodplain development will not aggravate existing flood problems or increase damage to other properties

Floodplain Management Definitions

Basement: Any area of the building having its floor subgrade (below ground level) on all sides.

Enclosure: The portion of an elevated building below the lowest elevated floor that is either partially or fully closed in by walls.

Lowest floor: Lowest floor of the lowest enclosed area. Should only be used for parking, access, or storage.

Post-FIRM/Pre-FIRM: Relates start of construction to the effective date of the community's floodplain management ordinance (i.e. if the start of construction was before the effective date, it is a Pre-FIRM structure).

Structure: A walled and roofed building or gas or liquid storage tank that is principally above ground. Also includes manufactured homes.

Substantial Damage/Substantial Improvement

Substantial Damage: Damage of any origin sustained by a structure whereby the cost of restoring the structure to its before-damaged condition would equal or exceed 50 percent of the market value of the structure before the damage occurred.

Substantial Improvement: Any reconstruction, rehabilitation, addition, or other improvement of a structure, the cost of which equals or exceeds 50 percent of the market value of the structure (or smaller percentage if established by the community) before the "start of construction" of the improvement.

Building Performance Requirements

NFIP has established minimum criteria and design performance requirements

Key NFIP Requirements for Zone A

IS 0280 Building Performance Requirements Table 2-1

Community Regulations and the Permitting Process

Regulation of the use of floodplain land is largely the responsibility of State and local governments

Communities may institute higher standards than those required by the NFIP, such as, but not limited to:

Adding freeboard requirements
Prohibiting building in certain areas
Requirements for building materials
Use and type of construction fill

Designer should always contact the local building official for building code and floodplain management requirements

National Model Building Codes

Include the I-Codes and the National Fire Protection Association (NFPA) Building Construction Safety Code (NFPA 5000, 2009)

The 2012, 2009, 2006, and 2003 I-Codes are consistent with the National Flood Insurance Program

As of January 2012, 47% of flood-prone communities had adopted a flood-resistant building code meeting or exceeding the NFIP

Sample covers of the National Model Building Codes

Consensus Standards

Relevant consensus standards for flood retrofit, developed by a committee of nationally recognized experts include:

ACI 530-08
ASCE 7-10
ASCE 24-05

Consensus Standards

Standards related to design and construction practices and construction materials are incorporated into a building code by reference rather than by inclusion of all of the text of the standard in the code

Relevant consensus standards include:

ACI 530-08, Building Code Requirements for Masonry Structures (referenced standard in IBC and IRC)
ASCE 7-10, Minimum Design Loads for Buildings and Other Structures (referenced in IBC, IRC, and NFPA 5000)
ASCE 24-05, Flood Resistant Design and Construction (referenced in IBC and NFPA; IRC allows, but does not require, provisions of ASCE 24)