The Southern Pine Inspection Bureau (SPIB) has handed over expanded and updated design values for visually graded southern pine. For higher grades and wider widths, requested changes include smaller cuts in the values than were implemented in June for No. 2 2x4s. SPIB’s requests now go to the American Lumber Standard Committee (ALSC) Board of Review for consideration.
Better Than Expected
Design values indicate how much a piece of wood can be expected to withstand pressures when used in construction. Engineers and designers rely on them to determine, for instance, how far a joist may span or how much weight a truss member can bear.
In January, ALSC reduced design values for visually graded No. 2 southern pine 2x4s by as much as 30%, but declined to change values for any other grades and sizes of the species until testing occurred.
SPIB’s new report, submitted in October, contains the results of those tests and the bureau’s recommendations. It also suggests a six-month waiting period before the enactment date of any changes.
“The results are encouraging, better-than-expected news for southern pine lumber producers and users,” says Cathy Kaake, vice president of technical marketing for the Southern Forest Products Association. “For example, the impact on joists, rafters, and headers is smaller than originally projected due to smaller reductions for the wider widths commonly used for those applications.”
While southern pine has dominated this issue, ALSC also has asked other organizations to test their own species. The Western Wood Products Association says its tests of Douglas fir and western larch found that the species have higher bending, tensile, and stiffness properties than when they were last tested in the 1980s.
—Craig Webb, editor, PROSALES.