Environmental Review FAQ

What are ABFEs and the best available data +1 standard?

Date Published: May 2014

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The Base Flood Elevation refers to the level of the flood that has a one percent chance of being equaled or exceeded in any given year. Advisory Base Flood Elevations (ABFEs) are maps that provide a better picture of current flood risk than the existing Flood Insurance Rate Maps (FIRMs), which in some cases are more than 25 years old. The new ABFEs are the recommended elevation of the lowest floor of a building. The ABFEs are based on FEMA coastal studies that were completed before Hurricane Sandy. The studies include data that has been collected and analyzed over a number of years. Though advisory now, eventually information used to develop the ABFEs will be incorporated into official FIRMs. The ABFEs are the required data source until new FEMA data such as Preliminary and Final FIRMs are issued. More information on ABFEs can be found on FEMA’s Region 2 website.

HUD and other Federal agencies are requiring an additional foot of elevation for projects in the Sandy recovery area. The additional foot is a safety precaution in anticipation of sea level rise and climate-related impacts. CDBG-DR funds require elevation of the lowest floor to one foot above the Base Flood Elevation shown in the best available data for new construction and substantial improvement of structures. Please note the following when applying the best available data plus one foot standard.

  • CDBG-DR funds require the best available data plus one foot for new construction and substantial improvement of structures.
  • Nonresidential structures must be flood-proofed, if not elevated, to the best available data plus one foot elevation consistent with FEMA requirements and guidance.
  • Some communities may require that the lowest floor be built above the best available data plus one standard, and if a community does so, that stricter standard would supersede this standard as the minimum requirement. Additionally, if the current FIRM enacted in a community has a higher elevation than the best available data plus one, then the higher FIRM standard would apply. Contact the local building official to determine floodplain management and other reconstruction requirements as well as how to obtain an elevation certificate for flood insurance purposes.
  • All mixed-use structures must be floodproofed, if not elevated, consistent with the latest FEMA guidance such as FEMA NFIP Technical Bulletin 3-93 and Technical Bulletin 6-93.
  • UD’s interpretation of lowest floor is consistent with the latest FEMA guidance on lowest floor. The current version of FEMA’s Elevation Certificate guidance for determining lowest floor elevations is available in the National Flood Insurance Program Elevation Certificate and Instructions.

Tags: Environmental Review Hurricane Sandy

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