Base Flood Elevation Explained: Why BFE Matters

What Is Base Flood Elevation?

Base Flood Elevation (BFE) is the computed elevation to which floodwater is expected to rise during the base flood, which is the flood that has a 1% chance of occurring in any given year. FEMA establishes BFEs through detailed hydrologic and hydraulic studies, and they are shown on Flood Insurance Rate Maps for Zone AE and Zone VE areas.

Think of BFE as the waterline during a major flood event. Everything below this line is expected to be underwater during a 1%-annual-chance flood.

Why BFE Matters for Insurance

Your flood insurance premium is largely determined by the relationship between your building's lowest floor and the BFE. If your lowest floor is at or above the BFE, your premium is significantly lower. For every foot your building sits below the BFE, premiums increase substantially. A home two feet below the BFE can pay three to four times more than one that is two feet above it.

BFE and Building Codes

Local building codes in flood zones require new construction to have the lowest floor at or above the BFE. Many communities require additional freeboard of one or two feet above the BFE for an extra safety margin. This requirement affects foundation design, utility placement, and overall building costs in flood-prone areas.

Finding Your BFE

BFE information is available on FEMA flood maps for areas that have been studied in detail (Zone AE and VE). If your zone is A without a suffix, it means a BFE has not been established, and you should check with your local floodplain administrator for available information. Search your ZIP code to find flood elevation data and risk information for your area.