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<br />Increased Building Costs <br /> <br />The cost of flood proofing ranged from $35,912forthe <br />building raised on fill to $89,732 for the building partially <br />raised on fill with watertight closures, The building raised <br />on columns had a flood proofing cost of $87,923, Thus, <br />flood proofing increases the cost of construction from 6 <br />to 16 percent. The corresponding degree of protection <br />ranges from 1 to 6 feet above the 1 OO-year flood level. <br /> <br />2 <br /> <br />Reduction of Flood Insurance Premiums <br /> <br />Without dry flood proofing, the annual premium for flood <br />insurance, based on $200,000 coverage at actuarial <br />rates, is $20,795 or nearly $1,00 a square foot. The flood <br />proofed building that is raised on fill to 1 foot above the <br />1 OO'year flood will have an annual premium of $575, <br />The building that is flood proofed through a combination <br />of fill and watertight closures designed to protect to 1 foot <br />above the 1 OO'year flood will have an annual premium of <br />$1,215, For insurance rating purposes, the building with <br />the watertight closures is credited for protection only to <br />the 1 OO'year flood level. When the building is raised on <br />columns to 6 feet above the 1 OO'year flood, the annual <br />premium will be reduced to $235, <br /> <br />The present value of the reduction in insurance pre- <br />miums over 20 years at 7 percent interest is zero for the <br />building that is wet flood proofed (rates do not now <br />recognize benefits that could accrue), $214,210 for the <br />building raised on fill, $207,430 for the structure which <br />combines fill and watertight closures, and $217,812 for <br />the structure raised on columns, <br /> <br />When the present value of the reduction or savings in <br />insurance premiums is compared to the cost of flood <br />proofing, the following benefit/cost ratios are derived, <br />Wet flood proofing the building is not economically feasi, <br />ble because there are no reductions in insurance pre. <br />miums at the present time, The building raised on fill to 1 <br />foot above the 1 OO-year flood has a benefit! cost ratio of <br />5,96, For the building raised on columns, the benefit! <br />cost ratio is 2,48, The building which combines fill and <br />watertight closures has the lowest economically favor, <br />able ratio of 2,31, <br />