Dimensional stability and mechanical performance of face-glued spruce-pine-fir and Douglas-fir studs

Warpage of dimensional lumber has been identified to be the major issue for its use in wood construction prefabrication companies in North America. Face-gluing is a promising technique to mitigate warp of dimensional lumber. This paper studies the dimensional stability and mechanical performance efficacy of 2-ply face-glued lumber to reduce warpage in both Spruce-Pine-Fir (S-P-F) and Douglas-fir (D.fir) lumber. Planks were paired and subsequently laminated based on their initial dynamic modulus of elasticity (MOE) and shape compatibility. Warp was measured in twist, bow, and crook at varying moisture contents. Mechanical performance was measured through the MOE, modulus of rupture (MOR), and shear strength. This pairing regime between component planks offers a means to reduce the twist and bow tendencies of face-glued lumber while increasing the lumber strength uniformity. Flexural MOE and MOR performances were consistent with visual grades of No.1/No.2, showing the potential of face-glued lumber as a value-added product for the automatic prefabrication of wood constructions.