The influence of growth characteristics on warp in two structural grades of southern pine lumber

The impact of growth characteristics on warp was evaluated for 438 pieces of grades No. 2 and No. 3 Structural Joists and Planks (22) (nominal 2 by 6 by 16 southern pine lumber (dry-dressed size 1.5 in. by 5.5 in. by 16.0 feet (3.8 cm by 14.0 cm by 4.88 m)). Compression wood cubed had significant influence on variation in bow. Compression wood cubed and wane had significant influence on variation in crook. Juvenile wood, distorted grain, slope of grain, specific gravity, fast-growth wood, knot area, knot quantity, and largest knot had no significant impact on variation in bow, crook, or twist in the graded lumber. Although certain growth characteristics did significantly influence the variation in either bow or crook, the total impact of these growth characteristics was slight. Regression analyses showed that the variation in bow, crook, and twist explained by growth characteristics ranged from 0 to 9 percent. Therefore, most warp in the study pieces was caused by factors other than the growth characteristics tested.

You must be logged in to download any documents. Please login (login accounts are free) or learn how to Become a Member