Document Douglas_doc_46a6a4abd2

FEMA 54 / March 1984 Elevated Residential Structures Federal Emergency Management Agency ---PAGE BREAK--- Elevated Residential Structures - a UE=1 M a ---PAGE BREAK--- Acknowledgments Many people contributed valuable assistance to the prepara- tion of this manual. We wish to acknowlege especially the guidance provided by Melita Rodeck and, later, John Gam- bel, the Federal Emergency Management Agency's technical representatives in this work. John Gambel's advice was particularly valuable in determining the final content and form of this manual. In addition, this project would not have been possible without the help of Richard W. Krimm, Assistant Associate Director of the Federal Emergency Management Agency's Office of Natural and Technological Hazards, who saw the importance of increasing architects' involvement in flood damage mitigation efforts. Finally, Ray Fox provided a wealth of useful advice in addition to his technical services throughout the course of the project. Prepared by The American Institute of Architects Foundation 1735 New York Avenue, N.W. Washington, D.C. 20006 Charles R. Ince, Jr., President Earle W. Kennett, Administrator, Research Donald E. Geis, Program Director and Project Manager Karen N. Smith, Administrative Manager Paul K. McClure, Editor Technical Consultants Raymond R. Fox Professor of Civil Engineering The George Washington University Washington, D.C. Mark Riebau Assistant Chief of Floodplain and Shoreland Management Wisconsin Bureau of Water Regulation and Zoning Madison, Wisconsin Cost Consultant Daniel Mann Johnson & Mendenhall, Architects-Engineers Washington, D.C. Paul Brott, Vice President Ernest Posch, Estimator Graphics and Book Design Assarsson Design Company Washington, D.C. Allan G. Assarsson, President Mark P. Jarvinen, Layout and Graphic Design Jeffery Banner, Graphic Design Photographs Raymond R. Fox, Dames & Moore, pp. 64 and 124 and Figures 4.23 and 4.26; Federal Emergency Management Agency, p. 1 and Figure 4.1; U.S. Geological Survey, pp. vi, 122, and 123; U.S. Department of Housing and Urban Development, p. 118 and Figure 2.3; Philip Schmidt, U.S. Department of Housing and Urban Devel- opment, Figure 2.7; National Park Service, pp. iv and 112; Spencer Rogers, p. 18; Rosenthal Art Slides, Figures 3.1 and 3.2; AIA Library, Figures 3.3 and 3.4; U.S. Army Corps of Engineers, pp. 3 and 115;Davis and Associates, Figure 4.49; Pittsburgh City Planning Depart- ment, p. 4; PARNG Photo, p. 2; and James K. M. Cheng, p. 98. Most of the photographs and design data in the Recent Design Examples section were supplied by the designers of the buildings shown there. All other photographs were taken by Donald E. Geis of The American Institute of Architects Foundation. Disclaimer The statements contained in this manual are those of The American Institute of Architects Foundation and do not necessarily reflect the views of the U.S. Government in general or the Federal Emergency Management Agency in particular. The U.S. Government, FEMA, and The American Institute of Architects Foundation make no warranty, express or implied, and assume no responsibility for the accuracy or completeness of the information herein. This manual was prepared under Contract No. EMC-C-0579 with the Federal Emergency Management Agency. The Design Studies section of the manual was developed on the basis of background data and design concepts submitted for the 1976 version of this manual by Zane Yost and Associates, Bridgeport, Connecticut; KEF Corporation, Metairie, Louisiana; Keck and Keck Architects, Chicago; Duval/Johlic Architects-Planners, San Francisco; Louisiana State University, Department of Architecture; Rhode Island School of Design; University of California at Los Angeles, School of Architecture and Urban Planning; and University of Miami, School of Architecture. . ---PAGE BREAK--- Table of Contents ACKNOWLEDGMENTS ii PREFACE v ENVIRONMENTAL AND REGULATORY FACTORS 1 FLOODING AND THE BUILT ENVIRONMENT 1 Riverine Flooding El Coastal Flooding FLOODPLAIN MANAGEMENT 4 National Flood Insurance Program El Base Flood Elevations E A and V Zones SITE ANALYSIS AND DESIGN 8 SITE SELECTION AND ANALYSIS 9 SITE DESIGN 13 Site Flooding Characteristics E Access and Egress E Vegetation El Flood Water Drainage and Storage [1 Dune Protection ARCHITECTURAL DESIGN EXAMPLES 18 DESIGN STUDIES 22 Bridgeport El Charleston and Newport E San Francisco C] Chicago AESTHETIC CONSIDERATIONS 35 RECENT DESIGN EXAMPLES 45 Logan House El Summerwood on the Sound E Breakers Condominium El Campus-by-the-Sea Facility E Starboard Village E Gull Point Condominiums DESIGN AND CONSTRUCTION GUIDELINES 64 FOUNDATIONS 65 Fill El Elevated Foundations E Shear Walls El Posts E Piles E Piers E Bracing FRAMING CONSTRUCTION AND CONNECTIONS 80 Framing Methods E Floor Beams El Cantilevers El Concrete Flooring Systems E Floor Joists E Subflooring E Wall Sheathing and Bracing E1 Roof Connections RELATED DESIGN CONSIDERATIONS 92 Glass Protection El Utilities and Mechanical Equipment El Building Materials El Insulation E Breakaway Walls El Retrofitting Existing Structures COST ANALYSIS 98 RESOURCE MATERIALS 112 GLOSSARY 113 SOURCES OF DESIGN INFORMATION 116 FEMA REGIONAL OFFICES 118 STATE COORDINATING OFFICES FOR THE NFIP 120 PERFORMANCE CRITERIA 125 REFERENCES 136 iii ---PAGE BREAK---
E A. - 'hi X raft; '0:0: rem u 0 0: 00 S A 00 And; ) i E o r 04 Concrete .E PIej Figure 3.7 A 23 I L ---PAGE BREAK--- CHARLESTOWN AND NEWPORT, RHODE ISLAND The architect here has chosen two case study areas, Newport and Charlestown, Rhode Island, with different cultural and natural conditions that affect flood design considerations. Newport is a compact commercial and recreation center that has many residences along the water's edge. The area studied in Newport is a protected harbor with access from Rhode Island Sound into Narragansett Bay. The portion of Charlestown that is the second study area is a beachfront area with vacation house development. Most develop- ment is in a coastal A Zone. Both study areas have high development pressures. In both areas historic, scenic and community values influence the design of elevated structures. In Newport the close proximity of a Historic District injects height, bulk, material, and size considerations into any planned development. (In the case of historic structures in floodplains listed on the National Register of Historic Places or a state inventory of historic places, restoration may be accomplished without elevating the first floor through a variance procedure.) Similarly in Charlestown, simply elevating structures, without regard for the natural environment, could produce ungainly and visually distracting elements. It is necessary in flood area design to not only meet engineering requirements, but to also be cogni- zant of the visual effect such design will have on the prevailing character of the area. Charlestown An inventory of critical natural factors was made to determine how and where development should take place in the Charlestown floodplain. As a result, specific land area within the floodplain was deemed acceptable for residential development. The analysis then proceeded to the evaluation of methods of elevation appropriate to the develop- ment area. 24 ---PAGE BREAK--- Base Flood Level Figure 3.8 For numerous functional and aesthetic reasons, earthfill with heavy stone revetment was chosen as the method for elevating residential structures in Charlestown (Figure 3.8). The homes were clustered to keep down the cost of fill and because the land available for safe building in the flood- plain was limited (Figure 3.9). A small-scale, Figure 3.9 25 ---PAGE BREAK--- single-family scheme was chosen for visual con- tinuity with earlier buildings (Figure 3.10). All houses, a small amount of private space, and all utilities are located on the common filled area. Low intensity land uses such as parking, road and driveways, playgrounds, etc., are located on the lower surrounding areas. Ramps and steps are used to accommodate the height differences from parking to the finished first floor. Figure 3.10 26 ---PAGE BREAK--- Newport Development in the wharf area in Newport, Rhode Island, is structured by a combination of natural and cultural conditions. Although separated from the older historic areas of Newport by a highway, its proximity to them requires special considera- tion of height, materials, and size. It is in a special flood hazard zone, yet its water's edge location makes it visually attractive. Changes in the use of the wharf area and its new relationship with neigh- boring areas have resulted in an expansion of com- mercial and residential development. The low height above sea level means that new structures would have to be raised approximately to the level of the highway to comply with local flood regu- lations. For the restoration of historic buildings, however, there is no need to elevate the first floor as long as a variance is obtained. Analysis indicated that the optimal solution would be a combination of elevation techniques, because different zones in the wharf area are suited to dif- ferent elevation strategies (Figures 3.11 to 3.13). Base Flood F igu re 3.1 1 < l~~~erm Ing ^ . ; Ecir . t Ii,. Base Flood ' MSL Figure 3.12 27 ---PAGE BREAK--- Figure 3.13 28 t ---PAGE BREAK--- In the area farthest from the water, earth fill offers flood protection and a gradual level change from that of the highway. A transitional middle section could combine berming with raised structures. Level changes can be integrated by linking extended decks with ramps and stairs. In the area closest to the water, raised structures would not alter the water-to-land relationship or block views. Commercial uses are most likely to locate in the filled area, where first floor spaces are usable. Residential, restaurant, and small office uses are more suitable to the raised structures, which afford increased privacy and better views. Spaces under and between the new buildings can be used for pedestrian malls and thus rein- force the tourist and commercial uses of the area. Decks, balconies and trellises can connect different building levels. Utilities for the raised structures could be run beneath these raised decks and trellises and then into the fill, being protected from flood damage. This manipulation of the spaces and level changes created by flood protection enhances the visual intricacy and human scale of the wharf. 29 ---PAGE BREAK--- SAN FRANCISCO, CALIFORNIA Pacific coast flooding is generally associated with high seas and rains. Ocean storms accompanied by high winds have caused considerable erosion and damage to beach and coastal floodplain property. Inland rain storms, on the other hand, falling on the mountainous terrain cause major canyon and valley flooding. Both coastal and canyon flooding are dangerous high-velocity situations. Slow-rising and lower-velocity conditions occur on coastal marshes and low-lying riverbeds. The architect has developed several very interesting and distinctive residential concepts for single- and multi-family housing. The use of landscaping, fences, and exterior decks minimizes the elevated appearance of the structures while providing func- tional visual highlights. Structurally the two concepts are quite different. Although both concepts use wood posts, the single-family residence uses a two-way structural grid supporting prefabricated housing units, while the multi-family structure is conventional wood frame construction built upon a wood-post-supported platform. Parking for both residential concepts is under the structure. Figure 3.14 30 ---PAGE BREAK--- Single-Family Residential Concept A two-way wood post structural grid supports the living units at levels above the base flood and serves to organize and unify the various units with minimal impact on the ecology of the area (Figures 3.14 to 3.16). A seven-foot clearance beneath the horizontal structural members allows for parking, storage, and sheltered recreation space separated from and below the living units. The reduced land coverage of this design is in keeping with the architect's concern for efficient land use. Shared facilities, clustering buildings, etc., further give these houses a unique identity and sense of community. Within the prescribed vernacular of poles, decks, railings, and fences, architectural variety with continuity is achieved. The fences are strapped together to prevent pieces from floating away if damaged during a flood. Water heater and furnace and air conditioning equipment are located 18 inches above base flood level with all ductwork in second floor or attic space. Figure 3.15 31 ---PAGE BREAK--- Base Flood Level Figure 3.16 32 ---PAGE BREAK--- Multi-Family Residential Concept To reduce costs, the architects have designed a conventional wood frame structure built upon a wood post platform (Figures 3.17 and 3.18). Raising the first floor to at least eight feet above grade provides an opportunity to put parking under the building. This reduces the area of the site that has to be built upon and places cars closer to apartments. However, parking under the structure requires fire separation. Exposed entrance stairs and fencing minimize the elevated appearance of the structure while providing visual variety and privacy. 1 Figure 3.18 33 Figure 3.17 ---PAGE BREAK--- CHICAGO, ILLINOIS Flooding in the Midwest is of two types: riverine and lake flooding. The characteristics of both are usually slow rise and low velocity. However, flash flooding and lake shore scouring can and do occur. The Great Lakes area, more specifically, the Wisconsin, New York, Ohio, and Michigan lake shores, have experienced growing problems of lake flooding and slow erosion caused by the increasing occurrence of high waters and high winds. Garden Apartment Concept Although elevated eight feet and constructed of reinforced concrete block, this rowhouse does not appear to be designed for a potential flood condi- tion (Figures 3.19 and 3.20). Tlhe covered parking and entrance level is handsomely integrated with the above living levels by reinforced concrete block walls that organize the entire structure. The walls are constructed parallel to the direction of possible water flow. Unfortunately, the architect enclosed the stairway-entranceway, with a potentially serious effect on flood insurance rates. : K 4 R Fiur 3.19 hit I " art . I I. I - Figure 3.20 34 Il I' i ,I I =71; ---PAGE BREAK--- Aesthetic Considerations There is a common misconception than an elevated residential structure will be inherently unattrac- tive-a box on stilts (Figure 3.21). This is not true. Elevated structures offer challenging design oppor- tunities to be aesthetically appealing as well as functionally sound. Residential development requires a significant financial investment, and if it is aesthetically appealing it contributes to the economic value of the area, both for the owner and for the com- munity as a whole. All communities have both positive and negative examples of this. Good quality tends to foster better quality, and poor conditions lead to even poorer conditions. Appealing design can thus be an important element of making the most of our limited development resources. Figure 3.21 35 ---PAGE BREAK--- SITE DESIGN Integration of development and site should be done so that the two complement each other. A careful site analysis can give many clues to the best design of the building for its relation to topo- graphy, location and orientation, and location of fenestration (views, etc.), and parking. Landscaping-creative use of trees, shrubs, fences, walls, etc.-serves two purposes. It integrates the elevated portion of the development with its surroundings and, at the same time, helps control erosion and protect the dwelling from the impact of debris and fast-moving water (Figures 3.22 and 3.23). The relationship and compatibility of development with the surrounding neighborhood and corn- inunity should be considered in order to give a sense of continuity with the surrounding areas, rather than an unattractive "hodge-podge" of un- related development. Terracing and level changes can be used to give a sense of variety and to identify different uses, as well as to integrate building with site. gA( H MYOUMP P f MOVING16 9 -St AW P ftioOW~fM tWOOPWAWrV~ qlqt6-1jo Figure 3.23 36 Figure 3.22 ---PAGE BREAK--- BUILDING DESIGN The integration of the foundation with the site and the building is perhaps the most important aesthe- tic challenge when designing elevated structures. Many elevated structures give the impression that the support foundations are treated separately from the building and the site, giving the impres- sion of a building set on spindly legs (figure 3.24). It is essential to recognize that the foundation is an integral part of a building, rather than only "some- thing to set the building on." A well-designed elevated residence should provide a smooth transi- tion from ground to dwelling, with the foundation integrated with and complementary to the building itself. Other special considerations when designing elevated residences include the design of any needed stairs and the use of the areas under the structure. More general considerations include the shape and form of the building (configuration, shape of roof, etc.), textures and color of building materials, the use and treatment of balconies, terraces, railings, windows, shutters, screens, and entries, and the arrangement of interior spaces. E Figure 3.24 37 ---PAGE BREAK--- Figure 3.25. This wood structure successfully uses the same material throughout the building- Figure 3.26. This is an example of integrating the foundation, structure, treatment of railings, wall, site, the building, and the foundation so they relate and roof material, as well as connection and well to each other. This foundation appears to be anchorage details. The design honestly expresses part of the building rather than stilts holding it up. the structure, foundations and other building It shows how a modest, simply designed building elements. While it is obvious this is an elevated can also be very aesthetically appealing through the structure, it still feels very much a part of the site. use of natural materials and interesting treat- The foundation members are also integrated well ment of fenestration and lighting fixtures. Simple with the building itself (see also Figures 3.54 to but well-thought-out landscaping ties the building 3.57). effectively to the site. Figure 3.27. This is a good example of how the configuration of a cluster layout can contribute to functional advantage as well as visual appeal. The sawtooth arrangement allows for two sides of each unit to have access/view to the ocean. This form also breaks up the long, continuous (and often mono- tonous) wall approach, thus adding variety and interest. With this configuration the materials, treatment and form of the units can be simple but still attractive. 38 ---PAGE BREAK--- Figures 3.28 to 3.29. This is an excellent example of cluster-type elevated residential development. The development is well-integrated with the site; the various levels seem to roll over and blend with the dune. The vegetation and simple fencing add much to this marriage. The individual units also relate very well to each other, providing a good example of an overall development's being "more than the sum of its parts." The individual units provide the individual amenities-privacy, plan layout, etc.-while still being a part of a comprehensive whole with a strong sense of community. The form, scale and character of the development are also excellent. The sloped roofs, the balcony treatment, use of levels, and the articulation of the other elements add variety and a character that complements the site and overall development. The use of materials-color, texture, scale-also contributes to the design's appeal (see also Figures 3.63 to 3.70). Figure 3.30. The exterior treatment of this devel- opment adds visual appeal to a development that could otherwise be quite monotonous. The exterior colored panels with white structure and coordinated interior panels provide interest, as does the simple treatment of balconies with a variety of planes, panels, railing and roof trellis members. 39 ---PAGE BREAK--- Figure 3.31. This is a good example of how a simple structural grid infrastructure can be used as a basis for a relatively modest, well-designed and visually appealing residence. The plan is simple, developed around the columns, but provides a very livable, interesting and functional space. The cantilevered balconies also add interest as well as defined exterior areas. The roof shape contributes to a spacious interior that makes the house feel larger than it really is, allows in natural light through the transom windows, and through its form adds much to the overall aesthetic appeal of the design (see also Fig- ures 3.40 through 3.45). 40 ---PAGE BREAK--- Figure 3.32. The diagonal battens used to enclose the stairwells for protection provide an aestheti- cally appealing screen-textural affect. The colored awnings also add a necessary highlight to an otherwise colorless exterior. Notice also the pole light fixture. Figure 3.33. Passersby have to look very carefully to see that this development is actually elevated. Good use of landscaping and building form includes attached and detached units. A:U D XA E :0 ; : :A Figure 3.34. This structure uses a mixture of materials, texture and color very successfully and provides a variety of form for visual appeal. The space under the building remains open and light through a combination of white unobstructed walls and piers, landscaping, and layout relative to other buildings. A human scale is accomplished by breaking the building up into different heights and sections, rather than an imposing three-story box, as is often done (see also Figures 3.58 through 3.62). 41 ---PAGE BREAK--- Figures 3.35 and 3.36. This is a good example of using a variety of shapes and forms (wall surfaces, planes, balconies, etc.) as well as wall treatments (materials, texture, color) to create a sense of variety essential for an aesthetically pleasing development. 42 ---PAGE BREAK--- Figure 3.37. In the interior, color, scale, texture, and floor arrangement must be given careful attention (see also Figures 3.40 through 3.45). 43 ---PAGE BREAK--- Figures 3.38 and 3.39. Well-designed elevated residential structures can take many forms and styles. The principles in this manual are applicable to any style. 44 ---PAGE BREAK--- Recent Design Examples The projects in this section are some of the best design examples discovered in a state-of-the-art survey conducted as part of the development of this manual. While these examples range from a single-family detached unit to a multi-family high rise, there appears to be a clear trend toward higher density, cluster-type development. This is probably due to higher land values and the experi- ence gained from major floods over the last couple of decades. This is a promising trend that encour- ages professional design involvement in residential structures and leads to a more comprehensive approach to elevated residential and other develop- ment in flood-prone areas. Virtually all the recent design examples that were submitted in response to our survey were coastal, as opposed to riverine, projects. This suggests that the state of the art is being set for the most part in coastal areas, especially in the higher-use resort areas. It should be noted, however, that what is being done in coastal areas can often be applied successfully in riverine, lake, and other flood- prone areas as well. 45 ---PAGE BREAK--- THE LOGAN HOUSE Tampa, Florida Architects: Rowe Holmes Barnett Architects, Inc., Tampa, Florida The Logan House (Figures 3.40 to 3.45), located adjacent to a federally protected tidal estuary near Tampa, Florida, exemplifies a skillful blend of flood protection and energy conservation. The natural site of the house, only four feet above sea level, suggested the possibility of flooding. Flood regulations required Rowe Holmes Associates to elevate the structure an additional six feet. They chose, however, to raise the house almost eight feet to be able to use the first level as both a carport and protected outdoor living area. The 2,000-square-foot structure is designed in what is known in Southern vernacular as the "dog trot" style, incorporating a long breeze- way/ventilating device covered with the same roof as the house but open on the sides. The wood frame house is supported on 10-inch-square pressure-treated pine poles augered deep into the soil to withstand hurricane forces common to this area of the country. The floor serves as a horizon- tal diaphragm to provide the pole structure addi- tional rigidity. Several of the features that protect the Logan House from flood damage also promote energy conservation. For example, elevating the structure, the major flood protection strategy, helps draw cool (lower) air up and through the house. A central utility core-unfortunately located on the lower level where it is vulnerable to storm forces-is serviced by a stairway, allowing pro- tected access to the carport and outdoor space. Figure 3.40 46 ---PAGE BREAK--- be- m b o om l bedroom bedroo T I ro w mo living level 0 5 S1 IsI: section O . south elevation O , 47 Figure 3.41 Figure 3.42 Figure 3.43 I II ---PAGE BREAK--- Figure 3.44 Figure 3.45 48 ---PAGE BREAK--- SUMMERWOOD ON THE SOUND Old Saybrook, Connecticut Architects: Zane Yost & Associates, Inc., Bridgeport, Connecticut Summerwood on the Sound (Figures 3.46 to 3.50), a 76-unit cluster development, won a 1979 design award for architects Zane Yost & Associates, Inc. The development is built on a peninsula tidal estuary protected by a barrier beach. Equal in importance to protecting the buildings from flooding was the preservation of the salt marsh ecological environment. For this reason, the architects chose to locate the units only along the natural contours of the 30-acre site. For further protection of land as well as buildings, the structures are elevated above flood level, topping crawl spaces with internal drains to permit flood water to pass in and out. The wood frame structures are covered with horizontal siding and use picket fences to soften the effect of the raised structures. Redwood stairs and decks adorn the water side of the units. Figure 3.46 Although the overall density on the site is low (2.5 units/acre), the clustering of the units makes for a comfortable neighborhood scale. 0 E i; iii i ; & . *w aIa ,g r Figure 3.47 49 ---PAGE BREAK--- SITE PLAN 0 25 50 100 Figure 3.48 _ Front Elevation I Ll rm Rear Elevation Figure 3.49 50 r a X II - 11 , , R , - e I L I k , - , " "
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1; o, "I I _ 7- -L 11 ---PAGE BREAK--- Figure 3.50 51 ---PAGE BREAK--- THE BREAKERS CONDOMINIUM Redington Beach, Florida Architect: Rowe Holmes Barnett Architects, Inc., Tampa, Florida The Breakers Condominium in Redington Beach, Florida (Figures 3.51 to 3.53), is composed of 38 two-bedroom units oriented to take advantage of a spectacular ocean view. Using a "double saw-tooth stepback" plan, the architects oriented the buildings around a communal atrium garden, creating a pleasant internal garden on an otherwise flat and treeless site. The 1,200-square-foot units, completed in 1973, are composed of exterior masonry walls and flat- slab and column construction to reach a height of 12 feet above sea level, which is the 100-year high flood elevation. A heavy Spanish stucco finish and louvered privacy screens made of red- wood soften the effect of the typical condominium construction. All the units share the atrium garden on either their entry or walkway sides. The units also share a game room and beachside pool and deck. Figure 3.51 52 ---PAGE BREAK--- site and first floor plan z Figure 3.52 longitudinal section Figure 3.53 53 ---PAGE BREAK--- CAMPUS-BY-THE-SEA FACILITY Catalina Island, California Architect: Leonard E. Lincoln, AIA, Palo Alto, California Catalina Island (Figures 3.54 to 3.57), developed as a resort center in the 1920s, is located 21 miles off the coast of southern California. Many of the original structures built on the island were destroyed by flash floods in 1980 when storm _ I ~ waters cascading down a series of ravines swept (T l :them off their concrete pier foundations. f !!sThe newly replaced key facilities of Campus-by- the-Sea, a conference center, are no longer threat- R ~~~ened by such flooding. For example, the new three-level dining complex makes use of poles that serve as both foundation and roof support for the 7,000-square-foot structure. The structure is supported by 55 poles, ranging from 25 to 40 feet Figure 3.54 in length. These poles are set on concrete pads, which were poured at the base of 10-foot-deep caisson holes. The poles were specially pressure- treated to resist decay and termite attack. A preservative (pentachlorophenol) was carried by a low-viscosity petroleum gas, allowing for deep penetration through the sapwood into the heartwood. Several of the new two-unit cabins on the site have also used this kind of structure, and more similar construction is expected to take place in the near future. Figure 3.55 54 ---PAGE BREAK--- Figure 3.56 0 0 I I A I * * 0 D I S H W A S H I N G 0 0 0 1~ - 4 0o 0 0 I 1 4 - . B.:L - m 0 0 FLOOR PLAN Figure 3.57 55 0 0 . K I T C H E N 0-7 - I 0 00 0 0 0 0 ---PAGE BREAK--- STARBOARD VILLAGE Pensacola Beach, Florida Architects: Davis & Associates, Architects & Planners, PA, Orlando, Florida Starboard Village (Figures 3.58 to 3.62) is a 33-unit condominium project consisting of six low-rise buildings on the Gulf of Mexico. All the living areas are raised above grade, allowing parking at ground level. Each building is designed with a module using a one-story unit with two-story units above. All structures are concrete frame and slab systems, supported on concrete-piling with shear walls designed to withstand hurricane forces. Wood-accented stucco as the primary finish main- tains a residential quality. The architects exercised special care in locating the air-conditioner units, mounting them under concrete stairs and on the underside of the second floor concrete slabs. Wood louvers then enclose the units. Figure 3.59 56 Figure 3.58 ---PAGE BREAK--- TYP. FLOOR PLAN SECTION 0 5 10 15 Figure 3.60 0 5 1 0 1 5 Figure 3.61 57 ---PAGE BREAK--- Figure 3.62 IX000 I' f f006'l08 0 fC0i>E X^ A ~ S , -A
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i t ---PAGE BREAK--- GULL POINT CONDOMINIUMS Perdido Key, Florida Architects: H. Shelby Dean-Richard H. Fox, Architects, Anniston, Alabama The design of this 16-unit condominium (Figures 3.63 to 3.70) on the Gulf of Mexico successfully integrates storm protection, energy conservation, function, and economics. The architects used pile construction to elevate the units several feet above the minimum required by the National Flood Insurance Program. This was done because analysis of the flood insurance premium rate structure showed that the added margin of safety from the additional elevation would qualify the units for significant savings in annual insurance costs. Figure j3.bJ 59 ---PAGE BREAK--- GULF OF MEXICO L ! available provide strong positive connection (Figure feAm 4.42). Metal straps can also be used provided proper All EACH J016T1 nailing is done and a sufficient number of straps is installed. At the minimum, every other joist and wall stud should be anchored with a strap, and even Figure 4.41. Wood Joist Anchors more for more severe loads (Figure 4.43). A good wood connector has also been developed. The capacity of these connections depends directly on the number of nails and their individual capa- city to resist loads transverse to their axis. Pullout resistance along the axis is not used; rather, the nails are placed at right angles (perpendicular) to the loads being transferred between the wood members. The number of nails counted in figuring the total connection capacity of a given joint is the lower number that exists on either side of the joint. For example, in the connection of a floor beam to a floor joist, if five nails are in the beam and four are in the joist, the capacity of the connection is limited by the four nails on the joist. AFig J4a5T5. - n Cs Figure 4.42. Metal Hurricane Clips 88 ---PAGE BREAK--- FLOOR JOISTS Cross-bridging of all floor joists is recommended to stiffen the floor system. The elevation makes the floors (particularly the first floor) more acces- sible to uplift wind forces, as well as to the forces of moving water and floating debris. Effective cross-bridging requires: - nominal 1 x 3's 8 feet on center maxi- mum - solid bridging same depth as joist 8 feet on center maximum. SUBFLOORING Two methods are commonly used for subfloor construction: nominal 1 x 4 or 1 x 6 boards placed diagonally over the floor joists (either tongue-and- groove or square-edge with expansion space between boards) and plywood subflooring used to create a floor diaphragm. When a plywood subfloor is planned, guidelines for thickness and methods of attachment in relation to joist spacing can be obtained from the Plywood Construction Guide published annually by the American Plywood Association. A well-constructed, firmly attached subfloor can be an important asset in resisting lateral forces. Figure 4.43. Metal Strapping Subflooring is typically nailed directly to the floor joists. Nailing with annular ring nails or deformed shank nails is recommended. These nails provide extra strength against pulling out when the floor system is exposed to loads other than gravity. A system of nailing and adhesive application of plywood with tongue-and-groove joints along the long edges of the sheet avoids the need for block- ing along these edges. This produces a more level floor and offers a stronger diaphragm action to resist horizontal flood forces. 89 5TKAyW I J KAI L.CV TO 6. ._NG I I. W l . -1 PIER ---PAGE BREAK--- FLOOR-JOIST-TO-WALL CONNECTIONS \ulrLtoo&K Elevated structures experience increased wind forces because wind speeds increase with elevation. A\ J01-5T -7 2e Exterior walls are used as tension members to PLA~h transfer wind uplift forces at the roof down to \P'AT v resistance provided by the foundation. It is usually necessary to use galvanized metal strap connections from alternate exterior wall studs to the floor joists or floor beams and from first floor studs to second floor studs (Figure 4.44). The capacity of these connections depends on the number of nails used. Manufacturers' brochures can be used to ascertain GALVAN4(ZW i connectors' capacity and thus the spacing required. VELTAL 5TRAP- HfEAPF-K WALL SHEATHING _9Tu P Plywood is the most common sheathing in use for Figure 4.44. Stud-to-Stud Connections exterior walls (Figures 4.45 and 4.46). The major advantages of plywood are that it braces the wall framing to resist racking stresses and it forms a continuous tie from floor beam to top plate when properly installed. Plywood used for sheathing structures elevated up to 10 feet above the ground should be exterior grade and not less than 1/2-inch thick. Nailing l/SOW17 SKA-p HIN l should be with sixpenny nails, spaced 6 inches A\ NAILfO T o along the edges of the panel and 12 inches on intermediate studs. Figure 4.45. Plywood AnchoeJ01 Figure 4.45. Plywood Anchorage 90 ---PAGE BREAK--- Structures elevated more than 10 feet should be sheathed with 3/4-inch exterior grade plywood, nailed with eightpenny nails, spaced as before. Deformed shank or annular ring nails and plywood with exterior glue are recommended. WALL BRACING Bracing vertical walls against racking is a common building practice, especially for weak materials such as some of the newer insulated sheathing. Wind forces and lateral forces from moving water are also significant factors in determining whether and to what extent to brace vertical walls. Common wall bracing methods are a let-in diagonal wood brace, diagonal boards and plywood. A common method similar to the let-in diagonal brace is a light-gauge galvanized steel strap nailed diagonally to each stud at the outside corners and framed walls. WALL-TO-ROOF CONNECTIONS Probably the most critical structural connections for wind resistance are those between walls and the roof. For single-family residences, the roof structure is usually roof rafters of 2 x 10's or 2 x 12's or roof trusses built up of 2 x 4's or 2 x 6's. Whether rafters or trusses are used, they should be spaced at about 16 inches or 24 inches on center (16 inches is the more common spacing). Roof con- nections are critical because these connections are limited in number-at most they can occur at every roof rafter or truss. SOFFHT TOP PI'AS- FX'fKItF ft-YWO5 WAL~L !5HEA-TH I K( CONTINUOU6 asM OF PFIATF -rO MAIN FLWOOR_ 13AJA Figure 4.46. Wall Sheathing Tie from Roof to Ceiling A number of available galvanized metal connectors place the nails in an orientation to best resist uplift and lateral forces. Manufacturers' brochures provide the necessary design information. 91 ---PAGE BREAK--- Related Design Considerations GLASS PROTECTION . X + t \Even moderate storms or routine high winds can cause large losses of glass in buildings, particularly along a coast. Broken glass may allow rain and D H-5ViUTTY IN floodwaters and high winds to enter the structure. CL\OST Water damage can ruin furnishings and eventually F05¶T IT i damage structural members. Wind allowed into an elevated structure increases the uplift load on the structure as it applies pressure to the ceiling and wall surfaces. Exterior shutters can be used to protect glass. For small openings the traditional louvered shutter cKIN& offers some protection. Additional protection is possible using 1/2-inch plywood attached to the back of the shutter, which will take the direct forces from the storm (Figure 4.47). This method Figure 4.47. Shutters for Window allows coverage of fairly large areas of glass. Protection UTILITIES AND MECHANICAL EQUIPMENT C>11 1l> Sewage Water Electric Structures in flood-prone areas are commonly served by combinations of electricity, water, I I 11 11 X~vl- IdI sanitary sewer, gas (both natural and bottled), 1 1 11 11 Ed 1 and telephone. Typical installations for these utilities expose them to potential damage from flooding and storm action. In the case of an K 1 1111elevated first floor, the connection from an under- ground utility line to the floor above further exposes the line to possible damage and/or con- tamination by flooding and storm action. Under- L%11X~ohr7 ULNA 1 ; 1 ground services are also susceptible to damage - *49 W I 11 Oe°} ^ s ;'gW~l<\X~t when erosion of the protective soil cover leaves S - l - - them exposed during flooding. Figure 4.48. Protective Utility Shaft Damage to utility lines can lead to contamination of drinking water, discharge of effluent from sewer lines, gas explosions, and fires and/or shock from damaged electrical systems. The most vulnerable section of any underground utility line is the portion between the ground and the place it enters the elevated first floor. A mini- mum amount of protection can be obtained by locating these utility risers on the sides of interior elevated foundation elements opposite the direction 92 ---PAGE BREAK--- of flood water. This can minimize damage from velocity water or floating debris. A more secure method is to place all utility lines coming from underground within a protective, floodproofed shaft tinder the elevated first floor (Figure 4.48). If electrical and telephone lines are supplied from overhead service lines, they should be connected through the utility company's meter system above the expected reach of flood waters. However, this requirement is often in conflict with the power company's policy regarding the reading of meters and their location. If this is not possible, the con- nection should be made within a waterproof Figure 4.49. Elevated CondensE enclosure. All distribution panels or other major electrical equipment should also be located above expected flood waters. Branch circuit wiring should be fed from the first floor ceiling downward to mini- mize wiring on the first floor. All mechanical equipment (furnaces, hot water heaters, air-conditioners, water softeners) should also be elevated above expected flood waters (Figure 4.49). An attic location, if available, would provide OVERHEAP UTILITY LIME X the equipment maximum safety. Heating and/or 7= cooling systems using ductwork to carry tempered air should be provided with emergency openings at their lowest elevations and a minimum slope on horizontal duct runs in order to allow the system to I HEALRE T WL 1 drain in case it becomes submerged. Figure 4.50 H HCA 1) 7 illustrates some of these concepts. PUMP INES Septic tanks should be floodproofed to ensure that flooding does not cause the tank to rise out of the ground if the tank is partially empty, as well as to ensure against discharge of effluent. BUILDING MATERIALS Figure 4.50. Locating Utilities One way to increase the safety of building materials is to elevate the building higher than the minimum floodplain management requirements. Even then, however, flood waters may still reach building materials, so they should be protected. A building elevated above grade has the underside of its floor area exposed to climatic and flood er Units 93 ---PAGE BREAK--- conditions, and will require special attention to protecting building materials. The climate and the desired appearance will determine whether the exposed underside of a floor should be sealed. Sealing exposed floors can protect subfloors and joists from the elements, improve insulation, and help conceal utilities. The material used to enclose floor spaces should be resistant to water damage or inexpensive to replace if it is not resistant to damage. Exterior grade plywood treated with preservatives is water- resistant and can be effective. Gypsum products should not be used unless an acceptable level of performance is assured. Regardless of the material used, some provision must be made to allow water that may find its way into the floor sandwich during storms and flooding to drain out, and for the joist spaces to dry out. Wood Wood exposed to the elements should be protected by treatment with any one of a number of chemical preservatives to make the wood resistant to fungi attack, insects, bacteria, and rot. Connections should be designed so that water will not collect on or in them. They can be protected with protective flashing, by treating saw cuts and drill holes with preservatives, and by painting connections. The American Wood Preservers Institute, Tyson's Inter- national Building, 1945 Gallows Road, Vienna, Virginia 22180, can provide specific guidelines. Steel In riverine areas steel framing and foundation members exposed to the elements should be pro- tected by galvanization or by painting with rust- retardant paints. The need for painting can be eliminated through the use of surface oxidizing steels (high strength low alloy). In saltwater environments, exposed structural steel shapes, beams, pipes, channels, angles, etc., undergo very rapid corrosion, and their use should be avoided. Small connecting devices such as bolts, angles, bars, and straps should be hot-dipped galva- 94 ---PAGE BREAK--- nized after fabrication and coated with a protective paint after installation. Standard galvanized sheet metal joist hangers and other connecting devices deteriorate rapidly despite their galvanized coating and also require additional protective coatings. Small anchoring devices, nails, spikes, bolts, and lag screws should, whenever possible, be hot-dipped galvanized. With sheet metal clips and hangers, the special nails used should also be galvanized. Regular inspection, maintenance, and replacement of corroded metal parts is necessary when steel is used in the coastal environment. Steel rods used to reinforce concrete or masonry piles or piers require special precautions to prevent saltwater from reaching the steel through hairline cracks in concrete or through masonry joints. This is discussed below. The American Iron and Steel Institute, 1000 Sixteenth Street, Washington, D.C. 20036, can provide specific guidelines. Concrete and Masonry The durability of reinforced concrete and masonry block can be improved by the use of chemical additives mixed with the concrete and mortar and by special treatments and coatings. Additives are numerous and vary from those that will prevent spalling due to freezing to those that will improve strength. Surface treatments and coatings, such as silicone and epoxy paints, can be used to reduce water absorption and penetration and to prevent damage by airborne pollutants. Guidance in the use of concrete and masonry can be obtained from the Portland Cement Association, Old Orchard Road, Skokie, Illinois 60076, and the National Concrete Masonry Association, P.O. Box 781, Herndon, Virginia 22070. INSULATION Like exposed walls of conventional structures, the exposed floor of elevated residences must be insulated against heat losses and heat gains. Depending on the climate, two factors should be considered. First, elevating a building will expose plumbing; such plumbing must be insulated against 95 ---PAGE BREAK--- Figure 4.51. Insulated Floor Section, Wood Post Foundation Figure 4.52. Insulated Floor Section, Foundation Wall freezing. In extremely cold climates, heating cables may be necessary with the insulation. Second, insulated floor decks may be subject to floodwaters and should therefore have either impermeable, closed-pore insulation able to with- stand water submersion or insulation that can be replaced economically (Figures 4.51 through 4.53). BREAKAWAY WALLS As indicated in Design and Construction Manual for Residential Buildings in Coastal High Hazard Areas, cited in the Preface, the area under an elevated structure in a V Zone must be free of obstructions or be constructed with breakaway walls latticework) designed to collapse under stress without jeopardizing the structural support of the building (Figure 4.54). Loads from flood waters and waterborne debris are critical considera- tions in designing breakaway walls. RETROFITTING EXISTING STRUCTURES Existing residential structures in flood hazard areas can often be raised in-place to a higher elevation to reduce their susceptibility to flood damage. The principal consideration in raising existing structures is often the cost; generally, the technology exists to raise almost any structure, even multistory buildings, but the cost increases as the difficulty increases. Residential structures have been satisfactorily raised up to nine feet. Aesthetics, intended use, needed flood elevation, and structural stability influence the height selected. Generally, the additional cost to raise a structure an additional foot or so is small compared to the initial set-up cost. The new foundation for an existing structure should be selected and designed as discussed earlier. Raising in-place is generally feasible for structures that are 1) accessible below the first floor for placement of jacks and beams, 2) light enough to 96 - IN5UIL):ON - aY FopM lN6UiYWOOV / -WATV- d-ist~AKt (JYF-UM W. SFFAY V-OA INSUfLAON -7 / V k F ~WATKR RKE616ATkKf rYPSUM 50. A~~~NNGUATlON 8 (RAS- FL-YWOO7 53: R~141Dj 2 S~GMY f~OAAf A IN5py-r. Wm rv .o ---PAGE BREAK--- be jacked with conventional house moving equip- ment, 3) small enough that they can be raised in one piece, and 4) strong enough to withstand the stress of the raising process. Wood frame residential and light commercial _-uLK structures with first floors above the ground (normally with an 18-inch crawl space beneath the first floor) are particularly suited for raising. Wood frame structures with basements below the first floor are also accessible and lightweight; however, raising the superstructure does not protect the basement, and the basement should IHT- 10 i l - I be filled with a granular material to provide struc- - T tural stability for the walls. Brick, brick veneer, and masonry structures, while heavier and more Ii fl difficult to handle, can also be raised. Utility equipment located in a basement can often Figure 4.53. Double-Insulated Floor be moved to a higher room, such as an upstairs Plenum, Pier Foundation closet, or an attic. It is important to ensure that the closet or attic floor can support the weight of the equipment. If necessary, an elevated addition can be built to house a furnace, hot water heater, and other equipment formerly housed in a basement. Protecting utility equipment in this way can be useful even if the house itself cannot or need not be raised. Raising a structure usually involves the following steps: - Disconnect all plumbing, wiring, and utilities that cannot be raised with the structure. -Place steel beams and hydraulic jacks beneath the structure and raise to desired elevation. - Extend existing foundation walls and piers Figure 4.54. Breakaway Walls or construct new foundation. - If a basement exists, remove water heater, furnace, etc., and fill basement with granu- lar material to support basement walls. - Lower the structure onto the extended or new foundation. - Adjust walks, steps, ramps, plumbing, and utilities and regrade site as desired. - Reconnect all plumbing, wiring, and utilities. - Insulate exposed floor to reduce heat loss and protect plumbing, wiring, utilities and insula- tion from possible water damage. 97 ---PAGE BREAK--- COST ANALYSIS or ---PAGE BREAK--- Once a community decides that the economic risk and environmental impact of developing floodplain land for residential use is acceptable, the dollar cost of that development must be evaluated. Two factors bear significantly on any such evaluation: first, the net cost of con- struction that meets the standards of the National Flood Insurance Program (NFIP) in light of the potential and unpredictable hazard of flooding and the losses that may ensue; second, the cost differentials between construction on elevated foundations and conventional build- ing methods. (Note that standards adapted by local jurisdictions are often more stringent than the NFIP's.) Repeated studies have shown that the savings that can be realized over the lifetime of a struc- ture by building on a raised foundation are usually considerable when compared with the one-time increase in construction costs for anr elevated foundation. This is largelv because the the one-time foundation costs are generally onlv five or six percent of the total cost of a residential structure. while the flood insurance savings that can be achieved over the life of a structure bv elevating it can be considerable. The economic cost to the individual of building a home in the floodplain consists of both flood damages that will occur and the costs of whatever measures are taken to mitigate such damages. The cost of flood damages to the homeowner may be partially shifted to federal, state, and local govern- ment through low-interest loans and tax deduc- tions for losses incurred. In communities parti- cipating in the NFIP, the owner of a new home can purchase flood insurance. Essentially, flood insur- ance allows the homeowner to spread the flood risk to others facing the same hazards and, more importantly, permits one to pay for expected flood losses, which are unpredictable as to size and time of occurrence, in predictable annual pay- ments. These are more manageable than un- expected flood losses, especially if more than one large flood happens to occur in a very short time. 99 ---PAGE BREAK--- / - 2.4 S01il 11F--- 4' Co S-e - , I , ~ 600011/ r, )1 -im. ~ tW 4' Com tt cd Gne.l \ rCr-I tn FOUNDATION SECTION L1- 1L J - 26'-O" 24-O" t EOF-O" I FOUNDATION PLAN SLAB-ON-G RADE $4.61 per square foot t61 _ 6 l ] t Acgeot6,4 12-0 -i L 26' O"0 24' - FOUNDATION PLAN CRAWL SPACE $5.13 per square foot I 10 -0 2et 16 00. tO'- 0-to 0 ~ 0 I r- - 3 d.10 Gidet Ba~eenttt Attoco. 1 2-0t 6.e~32' Steel OseeleInt I Dia. Ancbol dO~~~~s ~ i Mi Plywoo~d De~k Etob~~~emhdded 15" Min-~ 77 7 _210 2041, 8'0O C Me. 6" O-C. 2,E60 piet - 3-2,10 GiOto. 64 , T er m i ihildP. T.o WeIe to. 61 , < ,6,816 Cep 61-0k 3Cotomn end l4.4 / ~~~~~8.12,16 t1o, 00. e 1O e Cru hed , / , 5 Elewn COFrr« _ Di.. S-l O21. Gr'to o'C toneh 6/coot 4 C0)oe CloorSc O8el Drain T El- + _ F/,l co Weld oV6.6-6 Welded 80,10)30000 Toe' C9rLi;Loal & Set tin l- ttie OettttotOilO Tot St- # C o .1r4, Itt.I oleetis CO tioooo C dtoTe e dK Foot ito 20 ' SECTION FOUNDATION SECTION FOUNDATION PLAN Figure 5.1. Conventional Foundations (Estimates are spring 1983.) 100 .1 p11 A-1-11 dol --ede 1e M, ai I M - 1a6 Cs,, d S 1-s Fos -1ll 4;_UX iNt 6 BASEMENT $11.01 per square foot 26'-0" ,I V ---PAGE BREAK--- COST COMPARISON APPROACH The costs of post, pile, and pier foundations are compared here to each other and to the costs of conventional slab, crawl space, and basement foundations. Cost data and estimating forms are provided for roughly estimating one's particular foundation costs. 1. Slab-on-grade, crawl space, and basement foundations were selected as three of the most common types of residential foundations, and detailed drawings of them were prepared (Figure 5.1). Detailed drawings were also pre- pared for the three most typical elevation foundation types. These are post, pile, and pier foundations (Figure 5.2). (Regarding use of earth fill, see below.) 0,I o s' 2 .I O O. t. la " O C C . ~ ~ ~ ~ ~ ~ PI . 7x10eraier~~10 Di..bi 1-p0 r U I fi_ ' I [II I I J l I- 1- 1 ~ ~ I ; > O i.cnf TI lr I A [ h I > 1 . - p 1 2'.24"o24" - v 4 0 f. 'FN A IN 'C O 24 , ~~~~~~~~FOUNDATION SECTION CONCRETE PIER $7.08 per square foot 1. 2 Doll 2 Gsd2s X) t00 - - 2 I 8 B-0" 8'01 BK'-0 j8'j r B' 8 0 - 2B'=" 24-0" FOUNDATION PLAN I I0.0008..I, 2,18 H-0. II I I I I I I Il.Fr r= JL FOUNDATION SLITION WOOD POST $6.96 per square foot Wood Pol.. f hj! Jois , _ ' t 1 . A i 2 7 PLAN 8-0 8-0"/B' 8' 8-0" 8 8-0" 2d'_0 ' 24'-0" FCUNDATION PLAN , PIy2. 00 k I .,O11 Jit.''/ i_-g 1 I2tGild 60I. Gtd 2"Bs nl. v -0az"[§ r~~~~~~~Sieldo _f . ' 2x0ldr__T T' I SPIN lRinD, IB\.i"UDAO SECTION w~~j,&L / < , . I il, .,illili FOUNDATION SECTION WOOD PILE $6.58 per square foot DC.,ol T,..t.d Wo. Pil,, X _ r-TI IftF IW I FI ,A;!,FJF I ~ 28-0 B0" 24 B-0:SqId'O t ~FOUNDATION PLAN Figure 5.2. Elevated Foundations (Estimates are spring 1983.) 101 I I 2-1-Joit. S6 O.C.. - X0 -ot IB" O.C. ---PAGE BREAK--- Conventional Foundations Slab-on-Grade Crawl Space Basement Elevated Foundations Wood Post Wood Pile Concrete Pier $4.61 per sq. ft. $5.13 per sq. ft. $11.01 per sq. ft. $6.96 per sq. ft. $6.58 per sq. ft. $7.08 per sq. ft. Estimates-Spring 1983 Figure 5.3. Foundation Cost Estimates Elevated Foundations 2. The estimates are summarized in Figure 5.3. They are based on the foundation and deck of a 1,500-square-foot house, 28'x50', with a small offset. The total cost of this house is approximately $60,000, excluding land. All estimates were based on FHA construc- tion practices. 3. Using data from this cost sampling, the average cost of each conventional foundation type is compared to the average cost of each elevated foundation type. This comparison is done in two ways: first, each foundation as a percentage of the cost of the entire house (conventional foundations were established as base 100) and, second the dollar increase in the cost of the foundation above. Conventional Foundations Slab on Grade Crawl Spaces Basement % Increase of Total House Cost Dollar Increase, Foundation Cost Only Wood Post Wood Pile, Concrete Pier Wood Post Wood Pile Concrete Pier Figure 5.4 Cost Differentials, Conventional Vs. Elevated Foundations, for House Costing $60,000, Excluding Land. 102 +5.9 +4.9 +6.2 $3,525 $2,955 $3,707 +4.6 +3.6 +4.9 $2,745 $2,175 $2,925 -10.1 -11.1 -9.8 -$6,075 -$6,645 -$5,895 ---PAGE BREAK--- 4. Figure 5.5 graphically compares the cost of constructing the different types of foun- dations at various elevations. Note that increasing the elevation increases costs at a substantial rate only in the case of the fill option (which is based on the availability of usable fill material on the site). Slab+ Site fill 15 14 13 12 1 1 10 9 8 7 6 5 4 3 2 1 0 0 1 2 3 4 5 6 7 8 9 101112131415 ELEVATION (in feet) Figure 5.5. Relative Costs of Foundations Elevated to Different Heights 103 * Conc. piers . * Wood posts * 0 Wood piles co C''a 0 'a C CO) 0 C I- CD)00 ---PAGE BREAK--- Fill Fill can often be used in A Zones to elevate con- ventional foundations such as slab-on-grade. The cost of this approach varies widely, depending on the availbility, quality, and unit cost of fill as well as the height and compaction necessary. Local building officials or soils engineers should be consulted to evaluate local conditions. COST COMPARISON CAVEATS The comparative cost data given above do not take into account a number of factors that can affect either basic construction costs or long-term insur- ance costs. Insurance Costs Insurance rates under the NFIP vary greatly de- pending on the elevation of a building and other features related to flood safety. Differences in these rates can overshadow the construction cost differentials discussed in this chapter, and should be considered carefully in making design deci- sions. Design Assumptions Each house elevated on piles, posts, and piers was assumed to have 21 foundation elements. In addi- tion, each element was assumed to be an average length that included the length below grade and the length between grade and the structure. These are 16 feet for piles, 14 feet for posts, and 15 feet for piers. In practice, both the number and length of foundation elements will vary depending on soil conditions, expected flood levels, etc. Earthquakes Constructing elevated foundations in earthquake areas may require additional structural expendi- tures that should be noted in cost estimates. Local building officials or a structural engineer should be consulted to evaluate local conditions. 104 ---PAGE BREAK--- Stairs and Utilities Elevating a residence may result in increased cost for stairs and for utilities that must be elevated above grade. These costs were not considered in the estimates presented here since they vary with height of elevation, cost assignment, i.e., who pays for installation of utilities, and elevation method. Regional Cost Variations The cost data presented above are based on national averages, and do not take into account regional cost variations. Cost Inflation Building costs are difficult to predict because of the tendency for the cost of basic construction commodities-lumber, concrete, and steel-to fluc- tuate and to vary relative to each other. The costs here are estimated using data for the spring of 1983. Non-Cost Considerations Cost is not the only determinant for selecting the material and method for elevating. Market accept- ance (buyers and banks), architectural design inte- gration, climatic conditions, site conditions, and anticipated flood hazards should also be con- sidered. ESTIMATING FORMS The forms on the following pages can be used for making cost estimates for conventional and ele- vated foundations. 105 ---PAGE BREAK--- SLAB-ON-G RADE ESTIMATING FORM TO DETERMINE LOCAL COSTS Compute the following and enter: Square Footage of Floor Area Lineal Footage of Perimeter Square Footage of Foundation Wall Enter you costs (combine labor and material) and extend: Layout house on lot Trench for footing Place footings Lay-up or form & pour foundation wall Fill & grade for slab Place vapor barrier, wire mesh & insulation Place & finish slab x x x x x x LF LF SF SF = $ SF SF = $ Grand Total 106 $ ---PAGE BREAK--- CRAWL SPACE ESTIMATING FORM TO DETERMINE LOCAL COSTS Compute the following and enter: Square Footage of Floor Area Lineal Footage of Perimeter Square Footage of Foundation Wall Number of Piers Enter your costs (combine labor and material) and extend: Layout house on lot Trench for footing Place footings Lay-up or form and pour foundation wall Place pier footings Lay-up or form and pour piers Backfill Floor Girder Floor Framing Insulation & sealer Subfloor Place floor slab x x x x x x x x x x x LF LF SF Ea. Ea. CY LF SF = $ SF = $ SF = $ SF = $ Grand Total $ 107 - ---PAGE BREAK--- BASEM ENT ESTIMATING FORM TO DETERMINE LOCAL COSTS Compute the following and enter: Square Footage of Floor Area Lineal Footage of Perimeter Square Footage of Basement Wall Area Number of Basement Support Columns Enter your costs (combine labor and materials) and extend: Layout house on lot Excavation & spoil removal Place footings Place pier footings Lay-up or form & pour foundation wall Parge wall Set drain tile Backfill Place vapor barrier and wire mesh Place and finish floor slab Place girder Frame Floor Place subfloor x _ _ x _ _ x _ _ x _ _ _ _ x _ _ x x _ _ SF LF Ea. SF SF LF CY x SF x SF x LF x SF x SF Grand Total $ ---PAGE BREAK--- WOOD POST ESTIMATING FORM TO DETERMINE LOCAL COSTS Compute the following and enter: Square Footage of Floor Area Lineal Footage of Girders Number of Posts Enter your costs (combine labor and material) and extend: Layout house on lot Auger or dig post holes and remove spoil Place concrete punching pad Place poles Backfill poles and plumb Set girder Frame floor Place insulation & sealer Place subfloor x _ O ty x Oty x Qty x _ Oty x LF x_ SF x_ SF x _ SF Grand Total $ 109 ---PAGE BREAK--- WOOD PILE ESTIMATING FORM TO DETERMINE LOCAL COSTS Compute the following and enter: Square Footage of Floor Area Lineal Footage of Girders Number of Piles Total Lineal Footage of Piles Enter your costs (combine labor and material) and extend: Layout house on lot Bring pile-driving equip- ment to site Furnish and drive piles Set girder Frame floor Place insulation and sealer Place subfloor Grand Total x x LF x LF x SF x SF x SF $ 110 ---PAGE BREAK--- CONCRETE PIER ESTIMATING FORM TO DETERMINE LOCAL COSTS Compute the following and enter: Square Footage of Floor Area Lineal Footage of Girder Number of Piers Enter you costs (combine labor and material) and extend: Layout house on lot Auger or dig pier holes and remove spoil Place concrete footing Form & pour piers Backfill Set girder Frame floor Place insulation and sealer Place subfloor x Qty=$ x Qty=$ x Qty=$ x Qty=$ x LF x SF x x SF = $ SF = $ Grand Total $ 111 L ---PAGE BREAK--- RESOURCE MATERIALS ---PAGE BREAK--- Glossary Base Flood Elevation (BFE) The elevation for which there is a one-percent chance in any given year that flood levels will equal or exceed it (see Special Flood Hazard Areas). The BFE is determined by statistical analysis of stream- flow records for the watershed and rainfall and runoff characteristics in the general region of the watershed. Coastal High Hazard Area The portion of a coastal floodplain that is subject to high velocity waters caused by tropical storms, hurricanes, northeasters, or tsunamis. Labeled V Zones on Flood Insurance Rate Maps, these areas experience breaking waves of three feet or more. Debris Impact Loads Loads induced on a structure by solid objects carried by flood water. Debris can include trees, lumber, displaced sections of structures, tanks, runaway boats, and chunks of ice. Debris impact loads are difficult to predict accurately, yet rea- sonable allowances must be made for them in the design of potentially affected structures. Encroachment Any physical object placed in a floodplain that hinders the passage of water or otherwise affects flood flows. Existing Construction Those structures already existing or on which construction or substantial improvement was started prior to the effective date of a community's floodplain management regulations. Flood or Flooding A general and temporary condition of partial or complete inundation of normally dry land areas. Flooding results from the overflow of inland or tidal waters or the unusual and rapid accumula- tion of surface water runoff from any source. Flood Insurance Rate Map (FIRM) An official map of a community, issued or approved by the Federal Emergency Management Agency, that delineates both the special hazard areas and the risk premium zones applicable to the community. Zones are as follows: Zone A (unnumbered) - special flood hazard area inundated by the 100-year flood; deter- mined by approximate methods with no base flood elevation shown. Zones Al-A30 - special flood hazard area inundated by the 100-year flood; determined by detailed methods with base flood elevations shown. Zone B - area between the limits of the 100- year flood and the 500-year flood, or certain areas subject to 100-year flooding with average depths less than 1 foot, or areas protected by levees from the base flood. Zone C - area of minimal flooding; located out- side the limits of the 500-year flood. Zone V (unnumbered) - area subject to wave action, without base flood elevation shown. Zones VI-V30 - special flood hazard area of 100-year coastal flooding with velocity (wave action); base flood elevations shown. 113 ---PAGE BREAK--- Floodplain Any normally dry land area that is susceptible to being inundated by water from any natural source. This area is usually low land adjacent to a river, stream, watercourse, ocean, or lake. Floodplain Management The operation of a program of corrective and preventive measures for reducing flood damage, including but not limited to flood control pro- jects, floodplain land-use regulations, flood- proofing of buildings, and emergency prepared- ness plans. Floodway The channel of a river or watercourse and the adjacent land areas that must be reserved to discharge the one-percent-probability flood with- out cumulatively increasing the water surface elevation more than a designated height, generally one foot. Hydrology The science of the behavior of water in the atmos- phere, on the earth's surface, and underground. Hydrodynamic Loads As flood water flows around a structure it imposes loads on the structure. These loads consist of frontal impact by the mass of moving water against the structure, drag effect along the sides of the structure, and eddies or negative pressure on the structure's side. Hydrostatic Loads Those loads or pressures resulting from the static mass of water at any point of flood water contact with a structure. They are equal in all directions and always act perpendicular to the surface on which they are applied. Hydrostatic loads can act vertically on structural members such as floors, decks, and roofs, and can act laterally on upright structural members such as walls, piers, and foundations. Mean Sea Level The average height of the sea for all stages of the tide, usually determined from hourly height ob- servations over a nineteen-year period on an open coast or in adjacent waters having free access to the sea. New Construction Structures on which construction or substantial improvement was started after the effective date of a community's floodplain management regu- lations. One-Hundred Year Flood (See Special Flood Hazard Areas). Permeability The property of soil or rock that allows passage of water through it. Regulatory Floodway Any floodway referenced in a floodplain ordinance for the purpose of applying floodway regulations. Special Flood Hazard Areas Areas in a community that have been identified as susceptible to a one-percent or greater chance of flooding in any given year. A one-percent probability flood is also known as the 100-year flood or the base flood. Stillwater Elevations The elevation that the surface of the water would assume if all wave action were absent. 114 ---PAGE BREAK--- Storm Surge Watershed A rise above normal water level on the open coast due to the action of wind stress and atmospheric pressure on reduction on the water surface. Substantial Improvement Any repair, reconstruction, or improvement of a structure, the cost of which equals or exceeds 50 percent of the market value of the structure either before the improvement is started or if the structure has been damaged, and is being restored, before the damage occurred. An area from which water drains to a single point; in a natural basin, the watershed is the area contri- buting flow to a given place or stream. Wave Height The vertical distance between a wave crest and the preceding trough. Wave Crest Elevation The elevation of the 100-year storm surge plus wave height. 115 Storm Surge 1 Watershed ---PAGE BREAK--- Information Required Purpose or Implications of Data Possible Forms of Date Potential Sources of Data a National Flood Insurance Pro- * Requires local communities to * Program regulations * Federal Insurance Administration gram (NFIP) implement flocdplain regulations aInsurance rate information and * Federa Emergency Management * Sets minimum standards for tables Agency floodplain regulations * Flood Insurance Studies * State Floodplain Management * Prohibits federal funding for * Flood Maps Coordinating Agency projects in violation of floodplain Sect on 1362 Guidelines * Local Government Planning regulations Agency a Prohibits federa can guaran- tees for projects in violation of foodplain regulations * Establ shes flood insurance rate different als for properties in flood-prone areas * Local Government Planning * Implements floodplain regulations * Planning and Zoning Ordinances * Local Government Planning Programs * Determ nes ocal f oodplain * Zoning Maps Agency regulations based on NFIP * Bui ding Codes * Local Government Engineer guidelines (includes zoning and * Building Code Officials subdivision regulations, per- formance standards, Planned Unit Development ordinances. building codes etc.) Note Local regulations can be set at a higher standard than NFIP minimum standards de- pending on local needs and circumstances * State Floodplain and Coastal * Provides statewide floodpain * State program regu ations * State Floodplain Management Zone Programs development regu ations and * State development guidelines Coordinating Agency guidelines * State Office of Coastal Zone * Regulates development in Management coastal zones * State Of f ce of Natural or Water * Coordinates implementation of Resources NFIP in ocal jurisdictions and in areas where multiple state agencies have an nterest n f coding * Clearinghouse for Floodp ain Management Information * Regional P anning Restrictions * Can provide additional regula- * Program regulat ons *Regiona Authorities (e g Ten or Guidelines tions and guidelines for regional a Development guidelines nessee Valley Authority Appa- jurisdictions lachian Regional Commission.etc * Coordinates activities of differ- *Regional P anning Commissions ent agenc es within the region * R ver Basin Commissions * Source of nlormation and in some cases technical ass stance * Federal Agency Requirements * May include regulations relating * Program regulations U S Army Corps of Engineers and Guidelines (other than NFIP) to development in flood-prone * Environmental Protection Agency areas (e g Corps of Engineers * Federal Emergency Manage- perm ts for development on ment Agency nav gable rivers) * State Floodplain Management a May invo ve federal fund ng. the Coordinating Agency use of which is restricted in * Local Planning Agency flood-prone areas * Projects may requ re federal approva for development in flood-prone areas (e g En- v ronmental mpact Statements) Information Required Purpose or Implications of Data Possible Forms of Data Potential Sources of Information * Flood Hazard Boundaries * Determines where floodplain regulations Insurance and fed- eral financ ng restrictions apply * Determines specific flood haz- ard zones * Determines var able f ood insur- ance rate zones * Flood Hazard Boundary Maps * Flood Insurance Rate Maps a Flood Boundary and Floodway Maps a Hydrologic Atlases * Local Zoning Maps * Food Insurance Studies * F ood Depths * Ind cates e evarons at which * Flood Elevations flood damage is likely to occur a Water Surface Profiles a Determines appropriate build- * Stream and Coast Cross-sections ing elevations for meeting * Flood Insurance Studies floodplain regulations and flood insurance restrictions and rates * Indicates hydrostatic loads in flood-prone areas a Flood Water Velocity * Determines hydrodynamic cads in f ood-prone areas a Determines debris mpact cads n flood-prone areas * ndicates potent a[ for erosion and slope deterioration * Floodp ain Techn ca Studies * Hydrologic Studies * Flood Insurance Studies a Local Government Planning Agency a Local Government Municipal Engineer a State F oodplain Coordinating Agency * State Off ce of Natural Re- sources a Federal Insurance Administra- tion * Federa Emergency Manage- ment Agency * U S Army Corps of Engineers * U S Geologic Survey Sources of Design Information 'S c1 IX I .9I 116 ---PAGE BREAK--- * Warning Time * Indicates importance of emergency evacuation as part of the design program * Influences design of floodproof ng techniques such as f ood shields * Influences design of drainage systems * Influences design of wet f ood- proof ng techniques * Hydrographs * F oodp ain Technical Studies * Historical Records * Flood Insurance Studies * Duration of Flooding * Affects seepage into buildings * Floodplain Technical Studies and saturation of soils and * Historical Records building materials * Flood Insurance Studies * Affects the length of time facili- ties might be inaccessible or inoperable * Affects building design relative to orientation, configuration and choice of floodproofing techniques. * Frequency of Flooding * Influences site choice. * Floodplain Technical Studies * Affects choice of floodproofing * Historical Records techniques, especially those that require installation before every flood * Indicates need for special access * Climate and Weather * Indicates frequency and type of * Weather Service Records precipitation and in turn, the * Historical Records type and magnitude of flooding that is likely * Ground Water Level * Influences potential water * Geologic Surveys pressure on footings founda- * Soil Analysis Reports tions, and floors. * Affects site design techniques for controil ng water runoff * Structura Food Control Meas- ures dams levees chan- nel improvements) * Existing measures can affect site if the limits of the flood con- trol device are exceeded * Proposed measures can when implemented alter basic flood data * Feasibility Studies * Design Specifications * Probability Reports * Regiona Author ties -Tennessee Valley Authority -Appalachian Regiona Com- m ssion -R ver Basin Comm ssions * Hydrologic Engineer ng Con- sultants * Surveys by Professional Staff * U. S Department of the Interior Water and Power Resources Service (operates west of the M sIissippi River) I :1 PU a in1 Information Required Purpose or Implications of Data Possible Forms of Data Potential Sources of Information * Features * Affects location and magnitude * Topographic Maps * Local Government Planning of flooding on the site * Floodplain Technical Studies Agency * Identifies areas of the site that * Site Surveys should be avoided or protected * Local Government Municipal * Affects orientat on distribution Engineer and density of bur t elements on the site * State Floodplain Coordinating * Identifies physical constraints Agency and advantages for site devel- opment * State Office for Natural Re- sources * Topography * Influences siting of buildings * Topographic Maps * Indicates erosion potential. * Floodplain Technical Studies * Soil Conservation Service. U S * Indicates need for and feasibi - * Site Surveys Department of Agriculture ty of using, fill material on the site. * Indicates appropriate site de- * US Geologic Survey sign techniques for controlling water runoff * Regional Authorities * Soil Character st cs * Soil porosity influences the rate * Soil Maps * Hydrologic and Civil Engineer- of water runoff and flooding po- * Soil Analysis Reports ing Consultants tential * Site Surveys * Determines the feasibility and * Surveys by Professional Staff design specifications for use of fill material to elevate buildings * U S Department of the Inter or the use of backfill around foun- Water and Power Resources datons and construction of Service(operates west of the earth berms Mississippi River ) * Indicates required depth for footings, pilings, or columns * Slope Stabi ity * Affects choice of buiding sites * Analysis of combined effects of the use of fill material, and the topography and soil charac- design of foundations, footings, teristics and pilings * Site Surveys * Influences erosion * Indicates the need for terracing or ground cover to protect slopes * Vegetation * Aids in contro of water runoff, * Site Surveys and thus can be a factor in re- ducing flooding levels * Water Storage * Aids in control of water runoff * Geologic, soil and hydrologic and thus can be a factor in re- surveys ducing flooding levels * Site Surveys * Recharges ground water supplies 117 ---PAGE BREAK--- FEMA Regional Offices The Federal Emergency Man- agement Agency (FEMA) was created in 1978 to provide a single point of accountability for all federal activities related to disaster mitigation and emer- gency preparedness and response. It was established as an indepen- dent agency in the executive branch to consolidate a variety of existing agencies and offices performing related functions. The Federal Insurance Adminis- tration (FIA), formerly a part of the Department of Housing and Urban Development, is only responsible for administering the National Flood Insurance Program. This responsibility in- cludes assisting state and local governments in the implementa- tion of flood-plain management programs and providing informa- tion on flooding to communities and individuals. Regional offices are the primary means by which FEMA's programs are carried out at the state and local level. Connecticut, Maine, Massachusetts, New Hamp- shire, Rhode Island & Vermont Region III J.W. MacCormack Post Office Building, Room 442 Boston, Massachusetts 02109 (617) 223-9540 New Jersey, New York, Puerto Rico & Virgin Islands Region IV 26 Federal Plaza Rm. 1349 New York, New York 10278 (212) 264-8980 Delaware, District of Columbia, Maryland, Virginia & West Virginia Liberty Square Building 105 South Seventh Street Philadelphia, 19106 (215) 597-9416 Alabama, Florida, Georgia, Kentucky, Mississippi, North Carolina, South Carolina & Tennessee 1375 Peachtree Street, N.W. Suite 700 Atlanta, Georgia 31792 (404) 347-2400 q Region I Region II 118
, , , 1 1, V I
- ---PAGE BREAK--- Illinois, Indiana, Michigan, Minnesota, Ohio & Wisconsin Region VIII Colorado, Montana, North Dakota, South Dakota, Utah & Wyoming 300 South Wacker Drive 24th Floor Chicago, Illinois 60606 (312) 353-8661 Arkansas, Louisiana, New Mexico, Oklahoma & Texas Region IX Federal Regional Center Rm. 206 800 North Loop 288 Denton, Texas 76201 (817) 387-5811 Iowa, Kansas, Missouri & Nebraska 911 Walnut Street Room 300 Kansas City, Missouri 64106 (816) 374-5912 Region X Federal Regional Center Building 710, Box 25267 Denver, Colorado 80225 (303) 235-4811 Arizona, California, Hawaii & Nevada Building 105 Presidio of San Francisco San Francisco, California 94129 (415) 556-8794 Alaska, Idaho, Oregon & Washington Federal Regional Center 130 228th Street, S.W. Bothell, Washington 98011 (206) 481-8800 Federal Emergency Management Agency Regional Offices and Boundaries 119 Region V Region VI Region VII ---PAGE BREAK--- State Coordinating Offices for the NFIP Each of the states, in cooperation with the Federal Emergency Management Agency, has designated a specific agency to coordinate implementation of the National Flood Insurance Program. This agency provides a link between federal, state, and local levels of government and between different state agencies with flood-related responsibilities. The designated agency will typically be a depart- ment responsible for natural resources, emergency services, or physical development, and is a focal point for information relating to flood insurance and floodplain management. It can be an important source of physical data, information on community eligibility for flood insurance, relevant state regulations, references to other agencies, and, in some instances, technical assistance. The authority of each state's coordinating agency varies, and can best be determined through direct contact. Arkansas California Colorado Soil & Water Conservation Commission #1 Capitol Mall Suite 2D Little Rock, Arkansas 72201 (501) 371-1611 Department of Water Resources P.O. Box 388 Sacramento, California 95802 (916) 445-6249 Colorado Water Conservation Board State Centennial Building, Room 823 1313 Sherman Street Denver, Colorado 80202 (303) 866-3441 Department of Economics and Community Affairs State Planning Division P.O. Box 2939 3465 Norman Bridge Road Montgomery, Alabama 36105 (205) 284-8735 Department of Community & Regional Affairs Division of Municipal and Regional Affairs 949 East 36 Avenue Suite 400 Anchorage, Alaska 99508 (907) 561-8586 Connecticut Delaware District of Columbia Department of Water Resources Flood Control Branch 99 E. Virginia 2nd Floor Phoenix, Arizona 85004 (602) 255-1566 Dept. of Environmental Protection 165 Capitol Avenue Hartford, Connecticut 06106 (203) 566-7245 Dept. of Natural & Environmental Control Division of Soil & Water Conservation Edward Tatnall Building P.O. Box 1401 Dover, Delaware 19901 (302) 736-4411 Department of Consumer Regulatory Affairs 614 H Street, N.W. Washington, D.C. 20001 (202) 727-7577 Alabama Alaska Arizona 120 ---PAGE BREAK--- Department of Community Affairs Div. of Resource Planning and Management 2571 Executive Ctr. Circle East Tallahassee, Florida 32301 (904) 488-9210 Georgia Department of Natural Resources, Environmental Protection Division 19 Martin Luther King, Jr. Dr., S.W., Room 400 Atlanta, Georgia 30334 (404) 656-3214 Office of Civil Defense Post Office Box 2877 Agana, Guam 96910 011-[PHONE REDACTED] Hawaii Board of Land and Natural Resources P.O. Box 373 Honolulu, Hawaii 96809 (808) 548-7539 Department of Water Resources State House Boise, Idaho 83720 (208) 334-4470 Illinois Department of Transportation Division of Water Resources Local Flood Plain Programs 300 North State Street, Room 1010 Chicago, Illinois 60610 (312) 793-3864 Iowa Kansas Kentucky Louisiana Maine Maryland Iowa Natural Resources Council Wallace State Office Building Des Moines, Iowa 50319 (515) 281-5029 Kansas State Board of Agriculture Division of Water Resources 109 Southwest Ninth Street Topeka, Kansas 66612 (913) 296-3717 Department of Natural Resources Division of Water 18 Reilly Road Fort Boone Plaza Frankfort, Kentucky 40601 (502) 564-3410 Louisiana Department of Urban & Community Affairs P.O. Box 44455, Capitol Station Baton Rouge, Louisiana 70804 (504) 925-3730 Bureau of Civil Emergency Preparedness State House 187 State Street Augusta, Maine 04330 (207) 289-3154 Maryland Water Resources Administration Flood Management Section Tawes State Office Building D-2 Annapolis, Maryland 21401 (301) 269-3826 Department of Natural Resources 608 State Office Building Indianapolis, Indiana 46204 (317) 232-4160 Massachusetts Massachusetts Water Resources Commission State Office Building 100 Cambridge Street Boston, Massachusetts 02202 (617) 727-3267 121 Florida Georgia Guam Hawaii Idaho Illinois Indiana ---PAGE BREAK--- Michigan Department of Natural Resources Water Management Division P.O. Box 30028 Lansing, Michigan 48909 (517) 373-3930 Minnesota Department of Natural Resources Division of Waters 444 LaFayette Road St. Paul Minnesota 55101 (612) 296-9226 Mississippi Research & Development Center 3825 Ridgewood Road Jackson, Mississippi 39211 (601) 982-6376 Department of Natural Resources 1101 R. Southwest Blvd. P.O. Box 1368 Jefferson City, Missouri 65102 (314) 751-4932 Department of Natural Resources & Conservation 32 South Ewing Street Helena, Montana 59601 (406) 449-6646 Nebraska Natural Resources Commission P.O. Box 94876 Lincoln, Nebraska 68509 (402) 471-2081 Division of Emergency Management Capitol Complex Carson City, Nevada 89710 (702) 885-4240 New Hampshire New Jersey New Mexico New York North Carolina New Hampshire Office of State Planning 21/2 Beacon Street Concord, NH 03301 (603) 271-2231 New Jersey Department of Environmental Protection Division of Water Resources P.O. Box CN 029 Trenton, New Jersey 08625 (609) 292-2296 State Engineer Bataan Memorial Bldg. Santa Fe, New Mexico 97501 (505) 827-6140 New York Department of Environmental Conservation Flood Protection Bureau 50 Wolf Road-Room 422 Albany, New York 12233 (518) 457-3157 North Carolina Department of Natural Resources & Community Development Division of Community Assistance 512 North Salisbury Street P.O. Box 27687 Raleigh, North Carolina 27611 (919) 733-2850 Michigan Minnesota Mississippi Missouri Montana Nebraska Nevada 122 ---PAGE BREAK--- North Dakota State Water Commission 900 E. Boulevard Bismarck, North Dakota 58501 (701) 224-2750 Ohio Oklahoma Oregon Puerto Rico Rhode Island South Carolina South Dakota Ohio Department of Natural Resources Flood Plain Planning Unit Fountain Square Columbus, Ohio 43224 (614) 265-6755 Oklahoma Water Resources Board 12th Floor Northeast 10th & Stonewall Oklahoma City, OK 73105 (405) 271-2533 Department of Land Conservation and Development 1175 Court Street, N.E. Salem, Oregon 97310 (503) 378-2332 Department of Community Affairs 551 Forum Building, Room 317 Harrisburg, PA 17120 (717) 787-7400 Tennessee Texas Utah Puerto Rico Planning Board P.O. Box 4119, Minillas Station D-Diego Avenue Santurce, Puerto Rico 00940 (809) 726-7110 Rhode Island Office of State Planning Statewide Planning Program 265 Melrose Street Providence, RI 02907 (401) 277-2656 South Carolina Water Resources Commission 3830 Forest Drive P.O. Box 4440 Columbia, SC 29240 (803) 758-2514 Department of Military and Veterans Affairs Division of Emergency and Disaster State Capitol Pierre, South Dakota 57501 (605) 773-3231 Department of Economic- and Community Development Division of Local Planning 1800 James K. Polk Office Building 505 Deaderick Street Nashville, Tennessee 37219 (615) 741-2211 Texas Dept. of Water Resources P.O. Box 13087, Capitol Station 1700 North Congress Avenue Austin, Texas 78711 (512) 475-2171 Office of Comprehensive Emergency Management 1543 Sunnyside Avenue Salt Lake City, Utah 84108 (801) 533-5271 123 ---PAGE BREAK--- Environmental Conservation Agency Division of Water Resources State Office Building Montpelier, Vermont 05602 (802) 828-2761 West Virginia West Virginia Office of Emergency Services Room EB-80 Capitol Building Charleston, WV 25305 (304) 348-3831 Disaster Preparedness Office Box 1208 St. Thomas, VI 00801 (809) 774-6555 Virginia State Water Control Board P.O. Box 11143 Richmond, Virginia 23230 (804) 257-0075 Wisconsin Wyoming Department of Ecology Mail Stop PV11 Olympia, Washington 98504 (206) 459-6288 Department of Natural Resources Flood Plain-Shoreline Management Section P.O. Box 7921 Madison, Wisconsin 53707 (608) 266-1926 Wyoming Disaster and Civil Defense Agency P.O. Box 1709 Cheyenne, Wyoming 82003 (307) 777-7566 124 Vermont Virgin Islands Virginia Washington ---PAGE BREAK--- Performance Criteria The following performance requirements and criteria identify a range of considerations that should be addressed during the design of residential structures for flood hazard areas. These performance criteria do not represent the entire range of items applicable to each requirement. Instead, a selective number of criteria have been- presented. The performance requirements and criteria are applicable to all structural materials and all con- struction methods used in flood hazard areas. Traditional or conventional construction solutions, as well as innovative techniques, are acceptable so long as the performance requirements and criteria are satisfied. DEFINITIONS Terms important to proper interpretation of the performance requirements and criteria are defined as follows: Applicable Codes The system of legal regulations adopted by a community setting forth standards for the con- struction, addition, modification, and repair of buildings and other structures for the purpose of protecting the health, safety and general welfare of the public. Community Any state or political subdivision thereof with authority to adopt and enforce floodplain manage- ment regulations for areas within its jurisdiction. Design Flood (Base Flood) The design flood is the base or 100-year flood used for purposes of compliance with the National Flood Insurance Program (NFIP). Design Loads The design load is the minimum loading condition that the building should be designed to resist. Some loading conditions most likely will be defined in the applicable codes while other load conditions flood impact loads) will have to be determined. The following loads constitute the design load and should be considered as minimum loading conditions as defined in Criterion A.1 (see below): Dead Load The weight of all permanent construction. The dead load includes a) the weight of the structure itself, b) the weight of all materials of construction incorporated into the building that are to be permanently supported by the structure, including built-in partitions, c) the weight of permanent equipment, and d) forces due to prestressing. Gravity Live Load Gravity live loads result from both the occupancy (floor) and the environment (roof) of the building, as stipulated in the applicable code. These include, where applicable, loads caused by soil and hydro- static pressures. Wind Loads Wind loads stipulated in the applicable code. Restraint Loads Loads, forces, and effects due to contraction or expansion resulting from temperature changes, shrinkage, moisture changes, creep in component materials, movement due to differential settlement or combinations thereof. In coastal high hazard zones the 100-year flood includes wave height above the stillwater level. 125 ---PAGE BREAK--- Sec. 602.2.2 Lateral Loads Loads caused by the design flood, which include: - Flood-induced dimensional changes such as swelling of wood or heave of expansive founda- tion soils - Water loads as defined in Section 602.0 of the Corps of Engineers' publication, Flood- Proofing Regulations - Soil loads as defined in Section 604.0 of the Corps of Engineers' publication, Flood- Proofing Regulations Sections of 602.0 and 604.0 of Flood-Proofing Regulations (EP 116S-2-314, Office of the Chief of Engineers, U.S. Army, June 1972), are reproduced below: SECTION 602.0 WATER LOADS Sec. 602.1 Types Water loads, as defined herein, are loads or pressures on surfaces of the buildings and structures caused and induced by the presence of flood waters. These loads are of two basic types: hydrostatic and hydrodynamic. Sec. 602.2 Hydrostatic Loads Hydrostatic loads are those caused by water either above or below the ground surface, free or confined, which is either stagnant or moves at very low velocities, or up to five feet per second. These loads are equal to the product of the water pressure times the surface area on which the pressure acts. The pressure at any point is equal to the product of the unit weight of water (62.5 pounds per cubic foot) multiplied by the height of water above the point or by the height to which confined water would rise if free to do so. Hydrostatic pressures at any point are equal in all directions and always act perpendicular to the surface on which they are applied. For the purpose of these Regulations, hydrostatic loads are subdivided into the following types: Sec. 602.2.1 Vertical l[oads These are loads acting vertically downward on horizontal or inclined surfaces of buildings or structures, such as roofs, decks or floors, and walls, caused by the weight of flood waters above them. Lateral hydrostatic loads are those which act in a hori- zontal direction, against vertical or inclined surfaces, both above and below the ground surface and tend to cause lateral displacement and overturning of the building, structure, or parts thereof. Sec. 602.2.3 1plift Uplift loads are those which act in a vertically upward direction on the underside of horizontal or sloping surfaces of buildings or structures, such as basement slabs, footings, floors, decks, roofs and overhangs. Hydrostatic loads acting on inclined, rounded or irregular surfaces may be resolved into vertical or uplift loads and lateral loads based on the geometry of the surfaces and the distribution of hydro- static pressures. Sec. 602.3 Hydrodynamic Loads Ilydrodynamic loads . . . are those induced on buildings or structures by the flow of flood water moving at moderate or high velocity around the buildings or struc- tures or parts thereof, above ground level. Such loads may occur below the ground level when openings or conduits exist which allow free flow of flood waters. Hydrodynamic loads are basically of the lateral type and relate to direct impact loads by the moving mass of water, and to drag forces as the water flows around the obstruction. Where application of hydrodynamic loads is required, the loads shall be computed or estimated by recognized and authori- tative methods. \lethods for evaluating water velocities -and related dynamic effects are beyond the scope of these Regulations, but shall be subject to review and approval by the Building Official. Sec. 602.3.1 Conversion to Equivalent Hydrostatic Loads For cases when water velocities do not exceed 10 feet per second, dynamic effects of the moving water may be converted into equivalent hydrostatic loads by increasing the depth of water to the RFL) [use the level of the base or design flood], by an amount dh, on the headwater side and above the ground level only, equal to: aV2 dh = where V is the average velocity of the water in feet per second; g is the acceleration of gravity, 32.2 feet per second; a is the coefficient of drag or shape factor (The value of a, unless otherwise evaluated, shall not be less than 1.25) 126 Flood Loads ---PAGE BREAK--- The equivalent surcharge depth, dh, shall be added to the depth measured between the design level and the RFD and the resultant pressures applied to, and uniformly distributed across, the vertical projected area of the build- ing or structure which is perpendicular to the flow. Sur- faces parallel to the flow or surfaces wetted by the tail- water shall be considered subject to hydrostatic pressures for depths to the RFD only. Sec. 602.4 Intensity of Loads Sec 602.4.1 Vertical Loads Full intensity of hydrostatic pressure caused by a depth of water between the design elevation(s) and the RFD applied over all surfaces involved, both above and below ground. Sec. 602.4.2 Lateral Loads Full intensity of hydrostatic pressure caused by a depth of water between the design elevation(s) and the RFD applied over all surfaces involved, both above and below ground level, except that for surfaces exposed to free water, the design depth shall be increased by one foot. Sec. 602.4.3 Uplift Full intensity of hydrostatic pressures caused by a depth of water between the design level and the RFD acting on all surfaces involved Sec. 602.4.4 Hydrodynamic Loads Hydrodynamic loads, regardless of method of evaluation, shall be applied at full intensity over all above ground surfaces between the ground level and the RFD. Sec. 602.5 Applicability Hydrostatic loads shall be used in the design of buildings and structures exposed to water loads from stagnant flood waters, for conditions when water velocities do not exceed five feet per second, and for buildings and structures or parts thereof not exposed or subject to flowing water. For buildings and structures, or parts thereof, which are exposed and subject to flowing water having velocities greater than five feet per second, hydrostatic and hydrodynamic loads shall apply. 127 1
I ---PAGE BREAK--- Sec. 603.1.2 Special Impact Loads Sec. 604.1 Applicability Full consideration shall be given in the design of buildings, structures and parts thereof, to the loads or pressures resulting from the presence of soils against or over the structure. Loads or pressures shall be computed in accordance with accepted engineering practice, giving full consideration to the effects that the presence of flood water, above or within the soil, has on loads and pressures. When expansive soils are present, the Building Official may require that special provisions be made in foundation and wall design and construction to safeguard against damage due to this expansiveness. He may require a special investigation and report to provide these design and construction criteria. Flood Impact Loads (Fl) The loads caused by the design flood as defined in Section 603.0, "Impact Loads," and Section 605.0, "Hurricane and Tidal Wave Loads," of the Corps of Engineers' publication, Flood-Proofing Regulations. In the case of Section 605.0, where no specific guidance is provided, design loads shall be recommended by a professional engineer. (Also refer to FIA-7, Design and Construction Manual for Residential Buildings in Coastal High Hazard Areas, cited in this manual's preface.) Section 603.0 of Flood-Proofing Regulations is reproduced below: SECTION 603.0 IMPACT LOADS Sec. 603.1 Types Impact loads are those which result from floating debris, ice and any floatable object or mass carried by flood waters striking against buildings and structures or parts thereof. These loads are of three basic types: normal, special and extreme. Sec. 603.1.1 Normal Impact Loads Normal impact loads are those which relate to isolated occurrences of logs, ice blocks or floatable objects of normally encountered sizes striking buildings or parts thereof. Special impact loads are those which relate to large con- glomerates of floatable objects, such as broken up ice floats and accumulation of floating debris, either striking or resting against a building, structure, or parts thereof. Sec. 603.1.3 Extreme Impact Loads Extreme impact loads are those which relate to large floatable objects and masses such as runaway barges or collapsed buildings and structures, striking the building, structure or component under consideration. Sec. 603.2 Applicability Impact loads should be considered in the design of build- ings, structures and parts thereof as stipulated below: Sec. 603.2.1 Normal Impact Loads A concentrated load acting horizontally at the RFD or at any point below it, equal to the impact force, produced by a 1,000-pound mass traveling at the velocity of the flood water and acting on a one square foot surface of the structure. Sec. 603.2.2 Special Impact Loads Where special impact loads are likely to occur, such loads shall be considered in the design of buildings, structures, or parts thereof. Unless a rational and detailed analysis is made and submitted for approval by the Building Official, the intensity of load shall be taken as 100 pounds per foot acting horizontally over a one-foot wide horizontal strip at the RFD [use the level of the base or design flood], or at any level below it. Where natural or artificial barriers exist which would effectively prevent these special impact loads from occurring, the loads may be ignored in the design. Sec. 603.2.3 Extreme Impact Loads It is considered impractical to design buildings having adequate strength for resisting extreme impact loads. Accordingly, except for special cases when exposure to these loads is highly probable and the resulting damages are extremely severe, no allowances for these loads need be made in the design. Flood or Flooding - A general and temporary condition of partial or complete inundation of normally dry land areas from: 128 SECTION 604.0 SOIL LOADS ---PAGE BREAK--- the overflow of inland or tidal waters - the unusual and rapid accumulation or run- off of surface waters from any source - mudslides mudflows) which are proximately caused or precipitated by accumulations of water on or under the ground. - The collapse or subsidence of land along the shore of a lake or other body of water as a result of erosion or undermining caused by waves or currents of water exceeding antici- pated cyclical levels or suddenly caused by an unusually high water level in a natural body of water, accompanied by a severe storm, or by an unanticipated force of nature, such as a flash flood or an abnormal tidal surge, or by some similarly unusual and unforeseeable event which results in flooding as defined above. PERFORMANCE REQUIREMENTS AND CRITERIA FOR RESIDENTIAL STRUCTURES IN FLOOD HAZARD AREAS PERFORMANCE REQUIREMENT A The building, its contiguous structure(s), and its service systems shall be designed to withstand the design flood without causing unacceptable risks to its occupants or to adjacent property owners. The building complies with Performance Require- ment A if the following conditions are satisfied: Criterion A. 1: Strength The building is designed to resist the following loads, acting simultaneously: 1.1 D, L, R, and F 1.2 D, L, R, F, and Fl 1.3 D, L, R, W, F, and Fl 1.4 D, R, and F 1.5 D, R, W, F, and FL Where the working stress method of design is used the following provisions apply: 2.1 In load combinations 1.1 through 1.5 all loads are applied as listed or as required by the applicable codes for the same load combina- tions with loads F and Fl. 2.2 Allowable (working) stresses cannot be exceeded for loading conditions 1.1 and 1.4. For all other loading conditions the allowable stresses can be increased by the amount per- mitted in applicable codes for design against load combinations including wind or earth- quake load. Where ultimate-load design is used (such as instances where the American Concrete Institute, Building Code Requirements for Reinforced Con- crete [AC1 378, ACI, Detroit, current edition], is applicable) load factors are applied as recommend- ed in the applicable standard, and F will be com- bined with L, or factored as if it were a live load for loading conditions 1.1 and 1.4. For all other loading conditions loads F + Fl will be combined with W, or considered to be equivalent to a wind load. Test Structural analysis and/or physical simulation. Commentary The criterion provides a suitable margin of safety against structural collapse when the building is subjected to the base flood. The intent of the criterion is that the margin of safety for these buildings, when subjected to the base flood, be no less than the margin required for other build- ings not subjected to flooding. It is assumed that loads F may act on the building over a long period of time, while loads Fl are short-term loads. Thus the margin of safety against load combinations containing Fl need not exceed that provided against wind or seismic loads. 129 ---PAGE BREAK--- The combined load of earthquakes and floods is not considered here because of the low probabi- lity of a flood and an earthquake occurring simul- taneously. Where tsunami flooding is the base flood, earthquake loading should perhaps be con- sidered concurrently. Criterion A.2: Stability and Flotation There shall be a factor of safety of 1.5 against overturning, sliding, and flotation under the following load: D + W + R + F + Fl Test Structural analysis and/or physical simulation. Commentary This criterion provides a suitable margin of safety against sliding and overturning. The most critical load combination is being considered. Tie-down devices can be used to achieve structural stability, provided it can be demonstrated that deterioration of these devices during the service life of the build- ing or by flood conditions will not cause the factor of safety to fall below its stipulated value. Criterior A.3: Provision Against Debris and Scour Unless it can be demonstrated that the flood waters will be stagnant, or that there will be no floating debris during the design flood, the follow- ing provisions apply: 1.1 Building on stilts shall comply with Section 612.2.3 of the Corps of Engineers' publica- tion, Flood-Proofing Regulations. This section is reproduced below. Sec. 612.2.3 Building on "Stilts" direction of flood flow shall not be less than eight feet apart at the closest point. The "stilts" shall, as far as practicable, be compact and free from unnecessary appen- dages which would tend to trap or restrict free passage of debris during a flood. Solid walls, or walled in columns are permissible if oriented with the longest dimension of the member parallel to the flow. "Stilts" shall be of a type that causes the least obstruction to the flow and the least potential for trapping floating debris. Foundation supports for the "stilts" may be of any approved type capable of resisting all applied loads, such as spread footings, mats, piles and similar types. In all cases, the effect of sub- mergence of the soil and additional flood water related loads shall be recognized. The potential of surface scour around the stilts shall be recognized and protective measures provided, as required. 1.2 For flow velocities in excess of 5 feet per second the hydrodynamic loads in F shall be assumed to act over the entire width of the building, perpendicular to the direction of flow, and reasonable vertical clearance shall be provided for the passage of debris. The depth of all foundation elements shall allow for the potential effect of scour. Test Structural analysis and/or physical simulation. Evaluation of data and documentation for design, tests, and installation; evaluation of plans and specifications. Commentary Criterion A.3 is designed to prevent structural collapse caused by the accumulation of floating debris or the undermining of foundation elements as a result of scour. Part of the provision is de- signed to avoid debris accumulation. The other part provides adequate strength to resist the effects of the formation of a barrier over the entire width of the building. Buildings are exempt if it can be demonstrated that no debris will accu- mulate and no scour will occur. The building may be constructed above the RFD [use the level of the base or design flood] by supporting it on "stilts" or other columnar type members, such as columns, piers, and in certain cases, walls. Clear spacing of support members, measured perpendicular to the general 130 ---PAGE BREAK--- Criterion A.4: Disruption of Service Systems The service systems shall be designed to resist the loads stipulated in Criterion A.1 with safety margins as stipulated in A. 1 against disruptions which may endanger human lives. Test Engineering analysis and/or physical simulation. Evaluation of data and documentation for design, tests, and installation; evaluation of plans and specifications. Commentary This criterion only applies to disruption which may cause fatal accidents, such as rupture of gas lines. Lesser load levels are stipulated in B. 1 for disrup- tions which constitute a health hazard. Criterion A.5: Execution of Rescue Operations The building is designed to permit the execution of rescue operations. During the duration and at heights of the design flood the building shall: 1.1 Allow the safe evacuation of the occupants out of the building 1.2 Allow the safe transfer of occupants from the building to rescue vehicles 1.3 Provide means of access or adjacency for rescue vehicles. Test Evaluation of data and documentation for design, tests, and installation; evaluation of plans and specifications. Commentary Criterior A.5 is designed to prevent the entrap- ment of building occupants by rising water levels. Part of the provision is designed to provide means to evacuate the building windows, roof trap door). The other parts provide for the accomoda- tion and execution of rescue operations by boat, helicopter). 1t-X ,k " IS f f fX' I0 V\ f: i - 131 ---PAGE BREAK--- PERFORMANCE REQUIREMENT B The building, its contiguous structure(s), and its service systems shall be designed to withstand the design flood without causing unacceptable health hazards to its occupants. The building complies with Performance Require- ment B if the following conditions are satisfied: Criterion B. 1: Disruption of Utility Connections Building utility connections shall be designed to resist the following loads: At loading conditions: 1.1 1) + L+ R+W+ F +Fl 1.2 D+W+R+F+Fl The building utility connections should not sus- tain: 2.1 Permanently disrupted and/or broken attach- ment with their fixtures and/or supporting structural elements 2.2 Leakage or escape of effluent that could contaminate drinking water 2.3 Rupture of electrical service that could cause electrocution and/or fire. Test Evaluation of data and documentation for design, tests, and installations; evaluation of plans and specifications. Inspection and/or testing of built elements when deemed essential. Determination of conformances to generally accepted codes, standards and engineering and trade practices, where applicable. Commentary This criterion applies to all utility connections subject to the forces of the design flood. Utility connections which are designed to disconnect during the design flood without the release of deleterious substances are exempt from provisions 1.1 and 1.2. Criterion B.2: Provision Against Drinking Water Contamination There will be no contamination of drinking water with sewer effluent or flood water. Criterion B.2 and Performance Requirement B are deemed satisfied if the following provisions are met. 1.1 Approved backflow preventers or devices are installed on main water service lines, at water wells and/or at suitable building locations to protect the system from backflow or back siphonage of flood waters or other contami- nants in the event of a line break or temporary disconnection. Devices are installed at accessible locations and maintained in good working order. 1.2 Sanitary sewer and storm drainage system con- nections are provided with approved backflow preventers or devices installed at each discharge point. 1.3 No storm or flood waters are drained into systems designed for sewage only, and vice versa. Test Evaluation of data and documentation for design, tests, and installation; evaluation of plans and specifications. Commentary Criterion B.2 is designed to prevent contamination of drinking water with sewer effluent or flood waters. Also, the criterion is designed to prevent damage to fixtures and interior finishes floor- ing, wall surfaces) from backflow or back siphonage of flood waters. 132 ---PAGE BREAK--- Criterion B.3: Provision Against Contamination of Potable Water Wells Private potable water wells shall not be contamina- ted by toxic substances or impurities caused by the design flood. Criterion B.3 is deemed satisfied if the following provisions are satisfied. 1.1 Private potable well water is not supplied from a water table located less than 25 feet below grade, nor from any deeper supply which may be polluted by contamination entering fissure or crevice formations. 1.2 Each well is provided with a watertight casing to a distance of at least 25 feet below the ground surface that extends at least one foot above the well platform. Test Evaluation of data and documentation for design, tests, and installation; evaluation of plans and specifications. Geological analysis of site. Commentary Criterion B.3 is designed to prevent the contamina- tion of water wells used as a source for potable water. Part of the provision provides against the contamination of the water supply source. The other part provides against the contamination of the water removal system. In any case, local health codes should be consulted. 133 ! X- s~ r , ' * I, D i . e . . X '9 s i 46 j i I # W § X ---PAGE BREAK--- PERFORMANCE REQUIREMENT C The building, its contiguous structure(s), and its service systems shall be designed to withstand the design flood without sustaining damage of un- acceptable magnitude. The building complies with Performance Require- ment C if the following conditions are satisfied: Criterion C. 1: Provision Against Permanent Damage tinder loading conditions 1.1 through 1.3 the building as a whole, or any element thereof, shall not suffer permanent damage which would require replacement or major repair, or which would extensively impair its intended function. 1.1 D + l, + R +W + F + Fl 1.2 I) + + R + F + Fl 1.3 D + 1. + R + F + Fl The criterion is deemed satisfied if stress and de- flection limits under loading conditions 1.1 through 1.3 do not exceed those stipulated in applicable codes, or if it can be demonstrated that deflections caused by load combinations 1.1 through 1.3 can be accomodated by suitable detail and adequate flexibility of elements. Test Evaluation of data and documentation for design, tests, and installation; evaluation of plans and specifications. Inspection and/or testing of built elements when deemed essential. Determination of conformance to generally accepted standards and engineering and trade practices, where applicable. Commentary This criterion assures that the design flood will not cause excessive damage. Effects of swelling caused by increased moisture or inundation must be included in F. Criterion C.2: Provision Against Unnecessary Damage All living areas, major utilities, furnaces, and air- conditioning units shall not be submerged by the design flood. 1.1 Living areas shall be considered habitable areas that provide for the essential needs of people: living, sleeping, dining, cooking and sanitation. Recreation areas, libraries, and other speciality areas are to be considered habitable areas and therefore should not be submerged by the design flood. 1.2 The electrical system complies with Criterion C.2 if the following conditions are satisfied: 1.2.1 All portions of the electrical system installed below the design flood level are suitable for continuous submergence in water. Only submersible type splices are used and conduits located below the design flood level are self draining if subject to flooding. 1.2.2 Lighting panels, distribution panels, and all other stationary electrical equipment are located above the design flood. 1.3 The mechanical system complies with Criteri- on C.2 if the following conditions are satisfied: 1.3.1 Heating, air-conditioning, and ventila- ting are installed above the design flood. 1.3.2 All duct work for warm air heating systems located below the design flood level is provided with emergency open- ings for drainage of ducts after a flood condition. 1.4 The plumbing system complies with Criterion C.2 if the following conditions are satisfied: 1.4.1 Tanks, softeners and heaters are instal- led above the design flood. 134 ---PAGE BREAK--- 1.4.2 Plumbing below the design flood level will not suffer loss of stability or loss of tightness that will permit leakage or physical damage to fix- tures and joints and connections that will permanently impair functioning. 1.4.3 Utility connections designed to dis- connect during the design flood are easily reconnected. (See Criterion B.1.) Conmmentary Criterion C.2 is designed to prevent unmcessary damage of living areas, major utilities, furnaces, and air-conditioning units by the design flood. Part of the provision is designed to elevate living areas and equipment above the design flood. Other parts are designed to prevent the damage of utili- ties and mechanical/electrical connections below the design flood. Test Evaluation of data and documentation for design, tests, and installation; evaluation of plans and specifications. 135 ---PAGE BREAK--- References AIA Research Corporation. Design Guidelines for Flood Damage Reduction. Washington, D.C.: Federal Emergency Management Agency, 1981. American Concrete Institute. Building Code Requirements for Reinforced Concrete (ACI 318). Detroit: ACI, current edition. American Institute of Architects. Coastal Zone Management: Balancing Protection and Growth. Washington, D.C.: AIA Component Affairs, 1978. American National Standards Institute, Inc. 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Washington, D.C.: U.S. Government Printing Office, June 1981. Geis, Donald and Steeves, Barry. "Designing Against Flood Damage," AIA Journal, November 1980, pp. 52-58. General Adjustment Bureau, Inc. Nature's Des- tructive Forces. New York: GAB, 1973. Great Lakes Basin Commission. The Role of Vegetation in Shoreline Management. Chicago: U.S. Army Corps of Engineers, North Central Division 1977. Hunt, Charles B. Natural Regions of the United States and Canada. San Francisco: W.H. Freeman and Co., 1974. 136 ---PAGE BREAK--- Johnson, William U. Physical and Economic Feasibility of Nonstructural Flood Plain Manage- ment Measures. Davis, Calif.: U.S. Army Corps of Engineers Hydrologic Engineering Center, 1978. Kusler, Jon and Lee, Thomas M. Regulations for Flood Plains. Chicago: American Society of Planning Officials, 1972. Leopold, Luna B. Water: A Primer. San Fran- cisco: W.H. Freeman and Co., 1974. National Flood Insurers Association. National Flood Insurance Program-Flood Insurance Manual. New York: NFIA, current edition. National Science Foundation. A Report on Flood Hazard Mitigation. Washington, D.C.: NSF, September, 1980. Owen H. James. Annotations of Selected Litera- ture on Nonstructural Flood Plain Management Measures. Davis, Calif.: U.S. Army Corps of Engineers Hydrologic Engineering Center, March 1977. Pilkey, Orrin HI. Jr., Pilkey, O.H. Sr., and Turner, Robb. How to Live with an Island. Raleigh, N.C.: Science & Technology Section, North Carolina Department of Natural & Economic Resources, 1975. Phippen, George "A New Course to Ararat," Water Spectrum, Summer 1971, pp. 9-15. Sheaffer, John R. Introduction to Flood Proofing. Chicago: Center for Urban Studies, University of Chicago, 1967. Tennessee Valley Authority. Guide for the Use of Technical Information and Data for Floodplain Management in the Tenessee River Basin. Knoxville, Tenn.: TVA, October 1980. U.S. Army Corps of Engineers. Flood-Proofing Regulations. Washington, D.C.: U.S. Army, Office of the Chief of Engineers, 1972. U.S. Army Corps of Engineers. Low Cost Shore Protection. Washington, D.C.: U.S. Army, Office of the Chief of Engineers, 1981. U.S. President, Executive Order 11296, Flood- plain Management, Code of Federal Regulations, 1970 ed., Title 3, p. 181, USC 701. U.S. President. Executive Order 11988, Flood- plain Management. Federal Register, 42/101, 25 May 1977. U.S. President, Executive Order 11990, Protection of Wetlands. Federal Register, 42/101, 25 May 1977. U. S. Water Resources Council. Regulation of Flood Hazard Areas to Reduce Losses. Washington, D.C.: Water Resources Council, 1971-1972. U.S. Water Resources Council. Flood Hazard Evaluation Guidelines for Federal Agencies. Washington, D.C.: Water Resources Council, 1972. U.S. Water Resources Council. Unified National Program for Flood Plain Management. Washing- ton, D.C.: Water Resources Council, 1976. Waananan, A.O., et al. Flood-Prone Areas and Land-Use Planning-Selected Examples from the San Francisco Bay Region, California. U.S. Geological Survey Professional Paper 942. Washington, D.C.: U.S. Government Printing Office, 1977. Texas Coastal and Marine Council. Model Mini- mum Hurricane-Resistant Building Standards for the Texas Gulf Coast. Austin: September 1976. *U.S. Government Printing Office: 2001- 619-056/95398 137