This study aimed to investigate the durability of structural laminated veneer lumber (LVL) during outdoor use. We subjected LVL to outdoor exposure tests for 48 months; the tests were designed under the assumption of outdoor use such as temporary enclosure plates used in the construction field. The surfaces of the LVL specimens were painted, or preservatives were mixed with the adhesive in the glue line. Very slight changes were observed in the color of the specimens painted with solvent-born coatings. Modulus of rupture (MOR) in the flatwise direction after 48 months exposure was deteriorated to 60–80% of the initial value. The MOR in the edgewise direction was higher than that in the flatwise direction. The MOR values of the painted specimens were higher than those of the control specimens before 24 months of outdoor exposure, whereas after 36 months of exposure, the values of the painted specimens were almost equal to those of the control specimens. Shear strength retention was greater than MOR retention. We found that the face veneers of the specimens were deteriorated by outdoor exposure, whereas their inner layers were relatively sound.