What your flood zone means

Federal flood maps put each address in a zone, and the zone's letter says how likely a flood is there. In a high-risk zone the chance is 1 percent a year, or 26 percent over the life of a 30-year mortgage. Most homeowners and renters insurance doesn't cover flood damage.

The zones

The high-risk areas are the zones that begin with A or V. Together they make up the Special Flood Hazard Area, the land that a flood with a 1 percent chance in any given year would cover. That flood is also called the base flood or the 100-year flood. The name describes a 1 percent chance each year, not a flood once a century.

The letters after A say how much the map shows. In zone A no detailed study was done, so the map shows no flood depth or base flood elevation, the height the 1 percent flood is expected to reach. In zone AE the map shows base flood elevations. Zones V and VE run along the coast, where storm waves add to the flooding, and a VE zone shows base flood elevations from a detailed study.

Outside the high-risk areas the map uses zone X. A shaded X zone, or the older zone B, is moderate risk. It lies between the base flood and the flood with a 0.2 percent chance each year. An unshaded X zone, or the older zone C, is minimal risk, above that 0.2 percent flood.

An annotated example

What to do next

Look up your own address on the FEMA Flood Map Service Center. Enter the street address and open the dynamic map to see your FIRMette, the printable panel for your property.

A National Flood Insurance Program policy usually takes effect 30 days after you buy it, so a policy bought as a storm approaches won't cover that storm. A policy bought when you take out, increase, extend or renew a mortgage has no wait. The NFIP covers a building for up to $250,000 and its contents for up to $100,000.