New design values for visually-graded southern pine dimension lumber have been submitted for review.
The Southern Pine Inspection Bureau submitted the values, which will ensure the lumber can continue to be strong and reliable when used in construction, to the American Lumber Standard Committee.
The last major change for visually-graded dimension lumber occurred in 1991. Since 1994, the inspection bureau has conducted an annual resource monitoring programme developed in collaboration with the US Forest Products Laboratory.
The reason for the new values is a change in overall trends in the annual test data which suggested possible shift in the resource mix. These trends, along with anecdotal external information, prompted the bureau to conduct a year-long programme of testing and data review.
Design values for four of the properties – bending, tension, compression and stiffness – are based on data from testing full-size, commercially-produced lumber specimens.
