Table 3-6.-Nominal and Dressed Sizes of Lumber

Figure 3-29.-Laminated lumber.

LAMINATED LUMBER

Laminated lumber (figure 3-29) is made of several pieces of lumber held together as a single unit, a process called lamination. Usually 1 1/2-inches thick, the pieces are nailed, bolted, or glued together with the grain of all pieces running parallel. Laminating greatly increases the load-carrying capacity and rigidity of the weed. When extra length is needed, the pieces are spliced - with the splices staggered so that no two adjacent laminations are spliced at the same point. Built-up beams and girders are examples. They are built as shown in figure 3-30, usually nailed or bolted together, and spliced.

Lamination can be used independently or with other materials in the construction of a structural unit. Trusses can be made with lamination for the chords and sawed

Figure 3-30.-Built-up beam.