An Evaluation of Low-Grade Red Oak and Soft Maple as Raw Material for Cross-Laminated Timber Panel Production

Abstract

Abstract Utilization of hardwoods in the manufacture of cross-laminated timber (CLT) faces many challenges, one of which is the selection of raw material that is both technically and economically feasible. From an economic perspective, it would make sense to choose species and grades that are both readily available and relatively competitive with softwood species currently used in CLT manufacturing. For the purposes of this study, lower grades (2A Common, 2B Common, 3A Common, and 3B Common) of red oak and soft maple were deemed appropriate in fitting this profile. All lumber was visually graded according to both National Hardwood Lumber Association (NHLA) and Northeastern Lumber Manufacturers Association (NeLMA) grading rules, as well as nondestructively tested through flatwise bending to determine modulus of elasticity (MOE). The yield distribution of each species and NHLA grade, by visual structural grade, were analyzed. The mechanical testing of each species was analyzed based on the minimum allowable MOE of 1.2 x 106 psi as required by ANSI/PRG-320. Mechanical testing resulted in much higher yields of acceptable CLT material than visual grading, for both species. A total net worth analysis was conducted to evaluate the value of NHLA graded lumber being processed into structurally graded lumber for both species and both grading methods. Finally, a procurement analysis was conducted to determine the volume of lumber required for both species, in order to achieve a fixed volume of CLT-ready lumber.