EVALUATION OF REDUCED-THICKNESS STUDS

Reduced-thickness studs, measuring just 1-1/4 inches thick, are being manufactured and marketed by a northern Idaho sawmill company. The stu ds meet Western Wood Products Association grade standards for stress-r ated boards, which allows the assignment of allowable design values. O ur evaluation of these reduced-thickness studs included a Best-Opening -Face (BOF) computer estimation of the increased lumber yield, prelimi nary determination of allowable bearing loads, and a field evaluation in which the studs were used in the construction of a single-family ho me. The BOF estimation for lumber yield from 9-inch mean diameter, 8-f oot logs indicated a possible 18 percent increase in recovery when 2 b y 4 studs are the primary product being manufactured. In addition, whe n 2 by 4 and 2 by 6 studs were the primary products being produced, 24 percent more 2 by 4 studs and 14 percent more 2 by 6 studs could be m anufactured by sawing to reduced thickness. Engineering calculations d emonstrated that the reduced-thickness studs, graded as No. 2 Stress-r ated Boards, will support approximately 80 percent of the load-bearing capacity of full-sized 2 by 4 and 2 by 6 No. 2 Structural Light Frami ng exterior studwalls; a No. 2 Stress-rated Board 2 by 4 studwall will exceed the load-bearing capacity of a full-sized 2 by 4 Stud grade ex terior studwall by approximately 19 percent. Finally, field evaluation confirmed that when limited wane was allowed, the reduced thickness s tuds offered adequate nailing surface for drywall and exterior panel p roducts.