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3 1.3 Types of Structures The type of structure is an important consideration in the application of flood proofing measures, Four basic types of structures can be identified: residential, commercial, industrial, and mobile homes. Differentation between the type of structures is based upon occupancy, structural integrity, and costs justified for f1oodproofing each. The following discussion is directed toward the building and floodproofing of new structures. ~ In general, the only practical method of floodproofing new residential structures is to elevate the structure above the BFE. Other methods of flood proofing should only be employed when there are no other alternatives. Residential structures typically do not have the structural integrity to resist hydrostatic forces and flood proofing measures are costly when the structure is located below the base flood, Another major concern is the uncertainty with respect to the occupant's safety. The Federal Emergency Management Agency (FEMA) requires enactment of ordinances that require new residential structures to have the lowest floor elevation (including the basement) at or above the BFE. ~ Commercial structures are not significantly different from residential structures when con- sidering applicability of floodproofing measures. Small commercial businesses may not be able to justify costs and may not always have the personnel on hand at times when flood. proofing measures need to be implemented. Also, due to the use of these types of structures by the general public, an adequate flood-warning system must exist to enable timely eva- cuation, Commercial structures are considered non-residential by FEMA. ~ Due to the capital investment often associated with industrial-type structures, it is much easier to justify the cost of flood proofing. Also; industrial structures generally have the struc- tural capability to resist hydrostatic forces. Industrial plants that provide public and utility ser- vices need to operate and be accessible continually. Again, industrial structures are considered as non-residential by FEMA. Mobile homes are considered separate because they are highly susceptible to flood damage and require special anchoring to keep them secure when located below the BFE. Further dis- cussion of mobile homes can be found in Chapter XIV. . . When evaluating the level of a structure in relation to the BFE for either residential or non- residential structures, the lowest level of the structure, including the basement, must be con- sidered. Pictorial examples of different types of structures as defined in FEMA's Flood Insurance Manual are shown in the figures on the next few pages. . . . .