Flood zone AE also referred to as the 100 year flood zone has the highest premiums other than coastal areas. These are generally because most of the structures have a negative base flood elevation. So what determines the premiums of these zones?

Well there are a few things that have a major impact on flood premiums in these zones. The age of the structure, the foundation type, flood loss history, and the elevation of the home.

Let's start with the age of the structure depending on when the house was built it will have a different rating model through FEMA. Its based on the first flood map for structure which generally occurred after 1978. If it was before the first flood map its called a PreFirm structure and if its after the first flood map its called a PostFirm structure. One of the big differences between these two types of structures is called grandfathering where you can keep the property in a preferred flood zone that no longer exists. This is allowed on PostFirm structures but not PreFirm structures.

The next thing that has a major impact on flood insurances rates in flood zone AE is the foundation type. Let's start with crawlspaces above grade compared to subgrade. Above grade is a crawlspace that sits above ground and subgrade is going to be crawlspace that sits partially below ground. The big difference here is subgrade generally will sit a certain level below the base flood elevation which increase the premium. While above grade sits above ground it could still be below the base flood elevation. The difference is things like flood vents can significantly lower the premiums with above grade crawlspaces.
The next type of foundation that will have a major impact on premiums are basements. As you can imagine basements can sit a good distance below the lowest adjacent grade creating a significant negative elevation. This can have a big difference on the rate so its very important to understand this when owning a house and purchasing a house. Also just because a basement is below grade does not mean that it is below the base flood elevation. Now that we have talked about foundations lets talk about how the elevation of the home in a flood zone Ae can impact the rate.The only real way to know this is to have a survey or elevation certificate completed. Now that we have discussed how the elevations of a home can have a major impact on flood insurance rates as you can see from the different foundation types.

Lets talk about positive elevations first and how they can have a big impact. The further your home is above the base flood elevation the better the rate is going to be. If all the elevations of your home are above the base flood elevation your home might even qualify for a letter of map amendment. This means that your property might be removed from the high risk flood zone and placed in a low risk flood zones causing a big improvement to property values. Now lets talk about the impact of negative elevations. As mentioned above basements can cause a home to have an extreme negative elevation. The higher the negative elevation a home has the higher probability of a flood occurring. This can create a double edged sword because the NFIP rates can be through the roof sometimes exceeding $10,000 a year for non coastal properties. However the other problem is the higher the negative elevation the less likely that a private insurance carrier will offer coverage on a property. So these are some things to think about when buying a home with a basement or building a home. we have discussed the impact foundation types can have on a structure lets talk about flood loss history.

Flood losses can have a major impact on a property. It could even stop a property from selling if severe enough. Generally when one flood loss occurs you would lose the preferred rating with the NFIP if you had one. Having a flood loss can also eliminate most of the private flood insurance options as most will not insure a property that has had a loss. However when the second loss and paid claim occur is when disaster can strike. This can turn a property into a severity loss property which has to follow certain mitigation guidelines in order to get insurance through the National Flood Insurance Program and private flood insurance is not available on these type of properties. This is why you should really review things closely before filing a flood insurance claim.

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Chris Greene

Author

Chris Greene

President of The Flood Insurance Guru
M.S. in Emergency Management with a focus in Flood Mitigation
flood@communityfirstagency.com