Highest Adjacent Grade

Main Content

National Flood Insurance Program (NFIP) Policy Index


The highest natural elevation of the ground surface prior to construction next to the proposed walls of a structure. In AO Zones, all new construction and substantial improvements of residential structures shall have the lowest floor including basement elevated above the highest adjacent grade at least as high as the depth number specified in feet on the community's Flood Insurance Rate Map (FIRM); or at least two feet if no depth number is specified. All new construction and substantial improvements of non-residential structures shall meet the above requirements or, together with attendant utility and sanitary facilities, be floodproofed to the same elevation.

NFIP Requirement


IS-9 Managing Floodplain Development Through The National Flood Insurance Program (NFIP) (Pages 5-44, 5-45) (PDF 8MB, TXT 1MB) (entire document)

Related Keywords

Zone AO
Elevation Certificate

Last Updated: 
07/24/2014 - 16:00
Back to Top