Structurally, wood may be used for joists, posts, columns, beams, and trusses. It may also be laminated into structural shapes, such as columns, beams, rigid frames, arches, vaults, with fiberboard, particle board, plywood, or wood decking (plain or laminated) to form composite panels. Wood may be exposed and finished for interior or exterior use. It may be purchased pressure-treated to provide resistance to moisture, rot, or exposure.
Structural lumber is stress-graded for bending, tension parallel to the grain, horizontal shear, compression perpendicular to the grain, compression parallel to the grain, and modulus of elasticity. Structural lumber is usually dressed on four sides and, therefore, reduced from its normal size by approximately 1/2" in each direction. For example, the actual dimensions of a 6" x 10" beam dressed is 5-1/2" x 9-1/2".
Wood structures are fastened by nails, pins, dowels, screws, bolts, and adhesives, or by fabricated metal connectors, tailored to perform specific connection functions.