What is the difference between a Flood Hazard Boundary Map (FHBM) and a Flood Insurance Rate Map (FIRM)?

A Flood Hazard Boundary Map (FHBM) is based on approximate data and identifies the SFHAs within a community. It is used in the NFIP’s Emergency Program for floodplain management and insurance purposes. A FIRM or Digital Flood Insurance Rate Map (DFIRM) is normally issued following a flood risk assessment conducted in connection with a community’s conversion to the NFIP’s Regular Program. If a detailed assessment, termed a Flood Insurance Study (FIS), has been performed, the FIRM will show Base Flood Elevations (BFEs) and insurance risk zones in addition to floodplain boundaries. The FIRM may also show a delineation of the regulatory floodway. After the effective date of the FIRM, the community’s floodplain management ordinance must be in compliance with appropriate Regular Program requirements. Actuarial rates, based on the risk zone designations shown on the FIRM, are then applied for newly constructed, substantially improved, and substantially damaged buildings.