By Murray Wennerlund published 12-6-2020 updated 5-31-2022
Elevation IRC 2015 Section R322.2.1 requirements do not match those of HUD CDBG-DR or CDBG-MIT funded disaster recovery projects.
HUD has since Nov. 21, 2016 required that all HUD sponsored new construction in Special Flood Hazard Areas (SFHA) have the primary structure elevated to Base Flood Elevation plus 2 feet. This would include Zone A, and AO as listed below as well as AE.
HUD CDBG Docket No. FR-5989-N-01
"...must be elevated with the lowest floor, including the basement, at least two feet above the 1 percent annual floodplain elevation. Residential structures with no dwelling units and no residents below two feet above the 1 percent annual floodplain, must be elevated or floodproofed..."
IRC 2015
R322.2.1 Elevation requirements.
1. Buildings and structures in flood hazard areas, including flood hazard areas designated as Coastal A Zones, shall have the lowest floors elevated to or above the base flood elevation plus 1 foot (305 mm), or the design flood elevation, whichever is higher.
2. In areas of shallow flooding (AO Zones), buildings and structures shall have the lowest floor (including basement) elevated to a height above the highest adjacent grade of not less than the depth number specified in feet (mm) on the FIRM plus 1 foot (305 mm), or not less than 3 feet (915 mm) if a depth number is not specified.
3. Basement floors that are below grade on all sides shall be elevated to or above base flood elevation plus 1 foot (305 mm), or the design flood elevation, whichever is higher.