Minimum clear cover for bars in walls cast against and permanently exposed to earth is 3 in. Otherwise, minimum cover is 2 in. for bar sizes No. 6 and larger, and 11/2 for No. 5 bars or 5/8-in wire and smaller. Two points requiring special consideration are analysis for load factors of 1.7 times lateral earth pressure and 1.4 times dead loads and fluid pressures, and provision of splices at the base of the stem, which is a point of maximum moment. The footing and stem are usually cast separately, and dowels left projecting from the footing are spliced to the stem reinforcement. A straightforward way of applying Code requirements for strength design is illustrated in Fig. 9.38. Soil reaction pressure p and stability against overturning are determined for actual weights of concrete D and soil W and assumed lateral pressure of the soil H. The total cantilever bending moment for design of stem reinforcement is then based upon 1.7H. The toe pressure used to determine the footing bottom bars is 1.7p. And the top load for design of the top bars in the footing heel is 1.4(W  Dh), where Dh is the weight of the heel. The Code requires application of a factor of 0.9 to vertical loading that reduces the moment caused

Design/build client also has the architect on the developer team and not performing services for the owner. Designers/builders offer to design and construct a facility for a fixed lump-sum price. They bid competitively to provide this service or provide free design services prior to commitment to the project and as a basis for negotiation. Their design work is not primarily aimed at cost-performance tradeoffs, but at reduced cost for acceptable quality. The design/build approach to facilities is best employed when the owner requires a relatively straightforward building and does not want to participate in detailed decision making regarding the various building systems and materials. This does not mean that the owner has no control over these items. On the contrary, the owner is often permitted a wide range of selection. But the range of choices is affected by the fixed-cost restraints imposed by the designer/builder and accepted by the owner. When the facilities required are within the range of relatively standard industry-wide prototypes, this restriction may have little significance. A common misconception regarding design/build is that poor-quality work inevitably results. While there is a general benefit to the builder for reductions in material and labor costs, the more reputable designer/builder may be relied on to deliver a building within acceptable industry standards. Facilities where higher- quality systems, more sensitive design needs, or atypical technical requirements occur deserve the services of an independent design professional. Usually when the term program definition is used relative to an architect, it is understood to mean the clients program for physical space requirements in a building. With the decline in the office market in the late 1980s came the loss of, or minimum use of, the traditional developer and construction management/ construction consultant roles. As an outgrowth of the developer client era, certain developers and construction consultants turned their emphasis to program management. In this process, a firm is engaged by the client to manage the total development process, acting as the clients agent throughout the total process. The program management approach expanded the meaning of the word program beyond that normally associated with only the physical space program requirements. The term program in this new context defines the process of organizing and executing a project from inception to completion. This process takes into account legal, financial, funding, land acquisition, architecture, engineering, specialist consulting, design administration, insurance, construction administration, and facilities operation and/or management. The client, instead of managing portions of the process as in the traditional client and developer client scenarios, looks to one firm for managing

The large PSL sections can be resawn into a variety of smaller dimension lumber or timber products. An extensive use of this product is for beams and headers. Two pieces of 13/4-in-wide LVL can be nailed together to create a 31/2-in-wide beam for use in conventional 2  4 framing. Wider beams of LVL can be created by nailing three or more pieces together or by cutting larger sections from PSL billets. SCL is used for scaffold plank, truss chords, flanges for wood I joists, ridge beams in mobile homes, and a myriad of other building and industrial uses. Structural design properties for SCL are generally much higher than comparable values for sawn lumber. SCL is available with allowable bending stresses up to 3000 psi with corresponding modulus of elasticity up to 2,100,000 psi. ASTM Standard D5456 sets forth the procedures for determining the design properties for SCL products and published values vary among the various manufacturers. APA has promulgated a performance standard for LVL, PRL 501, which establishes uniform design properties among manufacturers. In addition to exhibiting higher strength characteristics than other wood products, design properties for SCL products have less variability. This is largely due to the control in manufacturing of natural strength-reducing characteristics of wood, such as slope of grain, knots, and density. Also, the random dispersal of these strength-reducing characteristics throughout the finished member tends to offset the individual effects of these defects on the overall strength of the end product, much like the use of varying grades of sawn lumber in the manufacture of glulam timber. This combination of higher strengths and reduced variability makes SCL an economical wood structural material. 10.30.5 Environmental Considerations With the increasing emphasis on more efficient uses of the available wood-fiber resource, engineered glued wood products are becoming more attractive. Each of the glued products described in the preceding articles makes optimum use of the base wood products in creating high-end, high-quality engineered products. Innovations in the engineered wood products industry are ongoing and it is these innovative engineered wood products that will allow wood to continue to be a viable construction material for building applications in the future. Frederick S. Merritt* Consulting Engineer, West Palm Beach, Florida This section discusses design and construction of systems generally used for enclosing buildings and the spaces within them. (Some such systems, such as roofs and foundations, however, are treated in other sections, because of their special functions in addition to enclosure of spaces.) The systems covered in this section, as described in Art. 1.7, include exterior walls; interior walls, or partitions; floors;