Douglas Fir-Larch design values confirmed

If fssrenN Wooo Products AssociV Y ation has completed testing of Douglas Fir-Larch lumber in cooperation with other western agencies.

Analysis of the 2012 test data indicates higher (+5.57o) bending strength, (+5.}Vo) tensile strength, and (+8.l%o) stiffness properties than those established in the 1980s' North American in-grade lumber testing program. The data has been submitted to the USDA Forest Products Laboratory for review. The analysis will be completed prior to consideration of the test report by the board of review of the American Lumber Standard Committee for confirmation at its January meeting.

The comparison to the properties established in the original in-grade testing program indicates no needed change to the published design values for Douglas Fir-Larch lumber. The monitoring program affirms current uses, building code recognition, and recognized span data for the species group will remain the same. Had the data indicated a shift in properties, the findings would have to be reviewed by the cooperating agencies' memberships and appropriate actions taken.

DOUGLAS FIR 2x4 lumber underwent bending tests at WWPA's testing facility to ensure no changes were required to published design values.

The coordinating western lumber agencies-including Pacific Lumber Inspection Bureau, Redwood Inspection Service, Timber Products Inspection, West Coast Lumber Inspection Bureau, and WWPA-have been working together since early 2011 on the testing program to monitor western lumber design values. This has resulted in the joint effort of these agencies on the sampling and testing of western lumber.

The published lumber design values are based on the in-grade lumber testing program. The testing plan was approved by the American Lumber Standard Committee board of review in 2011. The plan required destructive testing of 360 pieces in bending and 360 pieces in tension of Douglas FirLarch No. 2 2x4 lumber.

Professor Robert Fountain of Portland State University provided statistical support for the testing program. A total of 36 representative mills were selected for lumber sample collection from the Douglas fir and western larch production region. The test samples were representative of the lumber volume destined for the marketplace.

Following Douglas Fir-Larch, other western species including SprucePine-Fir (South) and Hem-Fir will be sampled and tested. The testing of western species is conducted periodically to monitor for changes, to allow for timely actions to be taken, if needed, to support lumber products.