FEMA maps are the basis for determining which areas will require flood insurance by a lender. Properties on the same street can vary, so it's important to check by the address.
The cost of flood insurance, unlike other insurance (auto, homeowners, etc.) is not based on your credit score. Uniform rates apply and are based on the age of the property and the base flood elevation (BFE) of the ground floor as compared to the BFE for that area in general.
If your property is at or above the BFE, obviously your cost is less. On the other hand, if your property is below the BFE, the premium will be higher. In fact, it can be more than your monthly note if it's a few feet below!
A flood elevation certificate is required to determine the BFE for exisiting construction. Local surveyors can provide this - cost is approximately $300-400, last I checked. Ask the seller if he has a certificate, if you are the buyer.
Hope this is helpful!
Sandra Jones, Burns & Co.
Hope this is helpful.