Determining Minimum Required Flood Insurance

We have a loan in the pipeline and received notice that the building is in a special flood zone area. The building is a multiple unit apartment building consisting of a basement and 4 floors. There was an elevation certificate done which showed that only the basement is in the flood area. There is nothing in the basement, and no contents stored there. I realize that in determining the minimum required flood insurance we have to take into consideration: 1-Replacement cost of the building / appraised value; 2- MAX limits of coverage: $500,000.00 limit for structure / $500,000 for contents (since this is a multiple unit apartment building), and the 3- loan amount. Our question is, once we assign a value, and because the flood area is only in the basement, as determined by the elevation certificate, since the building is 4 floors and a basement, can use 1/5 of the value as a factor in determining minimum required flood insurance?