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Southern Yellow Pine Design Value Changes

Posted by Suz-Anne Kinney on February 27, 2012

Earlier this year, the American Lumber Standards Committee (ALSC) reduced the design values for some grades and dimensions of southern yellow pine lumber. The new design values were recommended by the Southern Pine Inspection Bureau (SPIB) in order to address changes in the nature of the pine sawtimber being used to manufacture lumber.

Due to changes in forest management regimes in the South—the planting of fast-growing or genetically altered species, the application of herbicides to reduce competition or fertilizer to spur tree growth, to list a few—pine trees grow more quickly than ever, leaving wider spaces between growth rings. Unfortunately, because tighter rings mean stronger lumber, southern yellow pine trees are no longer as strong as they once were.

The new design values recognize this fact. They reduce by 25% to 30% some of the design values for No.2 2x4s, effective June 1. The new values cover all visually inspected lumber that meets these qualifications:

  • Dimensions: All lumber 2” x4” thick and 2” X 4” inches wide; in other words, everything from a 2” x 2” through a 4” x 4”.
  • Grades: #2, #3, Stud, Construction, Standard and Utility

The new rule does not assign specific design values for Dense and non-Dense No. 2s, however. Following the adoption of the new values, the SPIB asked the ASLC to set new standards for No. 2s classified as Dense or Non-dense based upon the previously pulled samples (i.e., dividing the No. 2 test sample used for the earlier design value changes into three groups—dense, non-dense and unclassified) and then using those results to determine the new values (dense getting a higher value than unclassified No. 2s and non-dense getting a lower value).

On February 23, 2012, the ALSC’s Review Board held a meeting to discuss this proposal, providing an opportunity for approximately 40 concerned industry parties to provide comments on the SPIB’s proposal. At the end of the meeting, the Executive Committee met and decided that more time was needed to study the SPIB’s proposal. One of the questions being debated concerns the sample used to set the new values.

The Forest Products Laboratory (FPL) points out, for instance, that the sample sizes used by the SPIB in this case were lower than the standard set out in ASTM D1990: “The approach used by SPIB to develop design values for these grades is outside the procedures described in D1990. Fully representative samples equal to or exceeding 360 pieces for Dense or Non-dense grade were not gathered.” In some of the tests, sample sizes ranged from 194 to 216. Despite this, the FPL’s preliminary assessment of the proposed values is this:

t would be inappropriate to continue to apply the past No. 2 Dense value to the current resource considering the reduced approved Unclassified design values and the observed reduced values for sorted No. 2 Dense and Non-dense. . . . If a representative sample of Dense and Non-dense had been gathered it is likely the values for Dense and non-dense would increase as more pieces are added and the lower tail becomes more fully defined. Therefore a case can be made that the proposed values determined by the smaller sample size sort method are likely conservative.”

Dr. Rubin Shmulsky, head of the Department of Forest Products at the Mississippi State University, who also submitted comments, points out that the “conservative” nature of the values is exactly the problem. Shmulsky argues that unless SPIB began with the objective of testing No. 2 Dense and Non-dense and then pulled samples specifically with a valid test of this objective in mind, the tests are invalid. “[T]he actual Dense classification lumber, as produced at the mill, would not intentionally occur in a pack of unclassified or Non-dense lumber; rather it would have already been removed.” As a result, the sample would be “necessarily biased and skewed below the Dense-class as pulled from these mills.”

According to Tom Searles, President of the ALSC, the Board will meet again on March 9, 2012 in order to further discuss the proposal. At that meeting, they will continue deliberations on this issue. It is uncertain at this point whether they will decide to accept the SPIB proposed values changes or whether they will, as Shmulsky writes: “remand the submission to SPIB pending further review, testing, and some type of proposal for investigation that actually seeks to address the issue of Dense classification lumber.”

As these issues indicate, the southern yellow pine industry is going through challenging times. And it doesn’t stop here. The SPIB is conducting further tests to determine if changes to the design values of other dimensions and grades are needed. While the modifications are in the best long-term interest of the industry (ensuring that both home builders and home owners have confidence in their products thereby preserving the market for SYP), the short-term pain of SYP lumber and building products manufacturers (as well as architects and builders) will be significant.

Caught between long-term gain and short-term pain, many in the industry are understandably looking for ways to bridge the gap. If you would like to provide feedback during the next conference call on this issue, visit the ALSC’s website: A meeting notice and agenda will be available there prior to the meeting.


J.W. Griffin


Since when did the University of Mississippi get a Department of Forestry Resources?


New Southern Pine Design Values Unlikely to Take E


[...] have a history of providing a six-month period after approval before new values go into effect. Changes to the southern pine 2 x 4 values that were approved in January of 2012 did not take effect .... In keeping with this tradition, it is unlikely that mills and consumers would feel the effects of [...]

Topics: Southern Yellow Pine lumber