Gateway/Flood Insurance Rate Map (FEMA flood zones)
Flood Insurance Rate Map (FEMA flood zones)
FEMA's official flood map: what Zone AE and Zone X mean, when lenders require flood insurance, and how to look up a St. Louis-area address.
| Published by | FEMA |
|---|---|
| High-risk zones | A, AE (Special Flood Hazard Area, 1% annual chance flood) |
| Moderate to low risk | Zone X (shaded and unshaded) |
| Lookup | FEMA Flood Map Service Center, msc.fema.gov |
What it is
A Flood Insurance Rate Map (FIRM) is the official map of a community on which FEMA has marked flood hazard areas. Lenders, insurers, builders and local floodplain administrators use it to decide who must carry flood insurance and where building rules apply.
Reading the zones
- Special Flood Hazard Area (Zones A and AE): land expected to be flooded by the 1% annual chance flood, often called the “100-year flood”. AE zones also show the base flood elevation.
- Zone X (shaded): moderate risk, generally the 0.2% annual chance (“500-year”) floodplain.
- Zone X (unshaded): minimal risk from river or coastal flooding.
A 1% annual chance flood is not a once-a-century event. Over a 30-year mortgage, a home in the Special Flood Hazard Area has about a one in four chance of being flooded at least once.
When flood insurance is required
If a building is in a Special Flood Hazard Area and has a mortgage from a federally regulated or insured lender, the lender must require flood insurance. Outside those zones flood insurance is optional, and FEMA notes that a significant share of flood claims come from properties outside high-risk areas. See National Flood Insurance Program.
What the map does not show
A FIRM shows flooding from rivers, streams and coasts. It does not show basement water from groundwater, hydrostatic pressure, a failed sump pump or a sewer backup, which cause most of the basement losses we see in St. Louis and are usually covered, if at all, by a homeowners policy endorsement rather than flood insurance.
Looking up an address
Enter the address at FEMA’s Flood Map Service Center (msc.fema.gov). St. Louis County, St. Charles County, Jefferson County, the City of St. Louis and the Illinois counties we serve each have their own map panels. Along the Meramec, Missouri and Mississippi rivers, check the map before buying, finishing a basement, or skipping flood coverage.
Key takeaways
- Zones A and AE are the high-risk Special Flood Hazard Area; Zone X is moderate to minimal risk.
- Lenders must require flood insurance in high-risk zones for federally backed mortgages.
- Flood maps do not cover groundwater, sump or sewer backup basement water.
Related glossary terms
Related services and guides
- Basement flooding cleanup
- Storm damage restoration
- Insurance claims assistance
- Basement and storm water guide
- Basement water in Greater St. Louis: flood, sewer backup or sump failure (PDF white paper)
Identifiers
References
- FEMA Flood Map Service Center
- FEMA: Flood maps
- FloodSmart (FEMA/NFIP)
- Wikipedia: Flood insurance rate map
Reviewed by Jake Lusby, owner of Gateway Water & Mold. Part of our entity reference pages. See our editorial policy to report an error.
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