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<br />u{ <br />~ <br />, <br />i <br />C <br />. <br />\ <br />t <br />t <br />t <br />( <br />( <br />( <br />( <br />'. <br />i <br />\ <br />I <br />( <br />( <br />( <br />\ <br />\ <br />( <br />( <br />t <br />. <br />, <br />i <br /> <br />questionable in the 10 to 15 year range. For a two story structure without basement, raising three <br />feet or five feet generally appears feasible below tne 7 year flood plain, not feasible above the 10 <br />year, and questionable between the 7 to 10 year flood plains. Because the cost data intersects <br />the damage reduced functions where they are generally at a moderate slope the general <br />feasibility conclusions stated above are not particularly sensitive to changes in cost. For example, <br />a 50 percent increase in cost would only change the flood plains indicated by three years or so. <br /> <br />Advantages and Disadvantages <br />Table 4-2 below summarizes the advantages and disadvantages of raising a structure in-place. <br /> <br />TABLE 4-2 <br /> <br />ADVANTAGES AND DISADVANTAGES <br />OF RAISING AN EXISTING STRUCTURE <br /> <br />Advantages <br /> <br />Damage to structure and contents is reduced <br />for floods below the raised first floor eleva- <br />tion. <br /> <br />Particularly applicable to single and two story <br />frame structures on raised foundations. <br /> <br />Structures have been raised to heights up to <br />nine feet. The greater heights are probably <br />most acceptable in wooded areas of steep <br />topography. <br /> <br />The means of raising a structure are well <br />known and contractors are readily available. <br /> <br />Raising in-place allows the user/owner to <br />continue operations at the existing location. <br /> <br />Flood insurance premiums are reduced. <br /> <br />Disadvantages <br /> <br />Residual damages exist when floods exceed <br />the raised first floor elevation. Minor damage <br />may occur below the first floor depending <br />upon use. <br /> <br />Not generally feasible for structures with <br />slab-on-grade foundations or structures with <br />basements (unless basement flooding is <br />tolerated). <br /> <br />Landscaping and terracing may be necessary <br />if the height raised is extensive. <br /> <br />References <br />1. U.S. Army Engineers, "Flood Proofing: Example of Raising a Private Residence", South <br />Atlantic Division, Technical Services Report, March 1977. <br /> <br />': <br />i <br />, <br />, <br />i <br />,. <br />( <br />( <br />i <br />( <br />r <br />i <br />" <br />I' <br />, <br />I <br />I <br />, <br />I <br />I' <br />i <br />I <br /> <br />25 <br />