Buyer's guides / Flood
How to read a Florida flood zone (and what it doesn't tell you)
"Zone X" sounds safe and "Zone AE" sounds alarming, but neither tells the whole story. Here's how to read a FEMA flood map like an underwriter, and the three questions to ask that the map can't answer.
The zones in plain English
- A, AE, AH, AO: a special flood hazard area, about a 1% chance of flooding in any year (the "100-year flood"). If you have a federally backed mortgage, flood insurance is required here.
- VE: a coastal high-hazard area, where waves add to the flooding. Building rules are stricter and insurance costs more.
- Shaded X (also called X500 or B): moderate risk, about a 0.2% annual chance (the "500-year flood").
- Unshaded X (or C): minimal mapped risk. Not no risk: a large share of flood insurance claims nationally come from outside high-risk zones.
The number that matters: base flood elevation
In A and V zones, FEMA's map gives a base flood elevation (BFE): the height the water is expected to reach in a 1%-chance flood, in feet above a vertical datum. What matters for a house is how its lowest floor compares with that number. A home whose lowest floor sits two feet above the BFE is in a very different position from one sitting two feet below it, even though both are "in Zone AE".
Ground elevation gives you a first look. If the ground at the house is well below the BFE, ask how high the floor is built. If the ground is above it, ask whether the whole lot is, or only part of it.
Ask for the elevation certificate
An elevation certificate (FEMA's form, completed by a surveyor or engineer) records the lowest floor elevation, the building's type and its flood zone. Many Florida sellers already have one, and some county or city floodplain offices keep copies for homes built or improved after the local flood rules began. It's the single most useful document for pricing flood insurance.
Florida's seller flood disclosure
For residential sales, Florida law (section 689.302, Florida Statutes) requires the seller to answer two questions in writing at or before the time the contract is signed:
- Have you filed a claim with an insurance provider, including the National Flood Insurance Program, for flood damage to the property?
- Have you received federal assistance for flood damage, including from FEMA?
The form also reminds you that ordinary homeowners insurance doesn't cover flood. A "yes" isn't a reason to walk away, but it's a reason to ask what happened, what was repaired and whether permits were pulled.
Three things the map can't tell you
- Street and drainage flooding. Heavy rain can flood streets and yards that sit outside any mapped zone. Ask the seller and neighbors, and look at the street after a storm.
- Storm surge. Flood zones and storm surge are related but not the same. A home can be in Zone X and still sit in a surge zone for a stronger hurricane. Check the National Hurricane Center's storm surge maps and your county's evacuation zone.
- How old the map is. Maps are revised. A pending map change can move a home into, or out of, a high-risk zone. Your county floodplain administrator can tell you whether new maps are coming.
Flood insurance timing
National Flood Insurance Program policies usually take 30 days to start, with an exception when the policy is bought in connection with a mortgage at closing. Private flood policies vary. Get a quote during your inspection period, not the week before closing.