Methodology

How we derive your flood zone.

Every number in your report comes from an official federal source, looked up live for your exact address. Here is where each part comes from, and the limits worth knowing.

1. We find your exact house

We pinpoint your specific address, not just your ZIP code. That matters because two homes on the same street can sit in different flood zones.

2. We read the official FEMA flood map

We look up your property on the FEMA National Flood Hazard Layer, the official flood map, and pull three things: your flood zone, whether it is a high-risk Special Flood Hazard Area (where a mortgage requires flood insurance), and the base flood elevation (the height floodwater is expected to reach) where FEMA has published one.

3. Recent disaster history for your county

We add your county's recent federal flood, hurricane, and storm declarations from OpenFEMA. It does not change your zone; it is context for how often the area has been hit.

What the zone codes mean

FEMA groups zones into three broad risk tiers. Your report explains the specific code it finds, but here is the full map:

• High risk (Special Flood Hazard Area): A, AE, AH, AO, AR, A99, V, and VE. These have roughly a 1% or greater chance of flooding in any given year. Flood insurance is required here with a federally-backed mortgage. The V and VE zones are coastal areas exposed to wave action, which carry the strictest building rules.
• Moderate to minimal risk: Zone X. Shaded X is the 0.2% annual-chance area (sometimes called the 500-year floodplain); unshaded X is the area of minimal mapped risk. Insurance is not federally required here, though flooding can and does still happen.
• Undetermined: Zone D. FEMA has not completed a flood analysis for these areas, so the risk is unknown rather than low.

On the "100-year flood" wording, honestly

A high-risk zone is often described as the "100-year floodplain." That phrase is widely misread. It does not mean a flood happens once a century. It means there is about a 1% chance of that flood level being reached in any single year. Over a 30-year mortgage, the cumulative odds are much higher than most people assume, better than one in four. We use the 1%-annual-chance framing in the report because it is the accurate way to read the risk.

Precision and caveats

• Point, not parcel. We look up the single coordinate your address resolves to. A large or irregular lot can span more than one zone; the point may not capture that.
• Maps get revised. FEMA updates flood maps over time. A zone can change when new studies, levees, or map revisions take effect. The report reflects the map as of the day you run it.
• Not an official determination. Lenders order a separate Standard Flood Hazard Determination Form. Confirm anything that affects money at the FEMA Map Service Center and with your insurer or lender.