They Don’t make ‘Em Like They Used To – Update #3 (August 21, 2012)
We have been posting on the changes in the design values for Southern Yellow Pine. You might recall that recent test results for the strength values of 2×4 lumber showed that the strength values for Southern Pine are about 33% lower than listed on the strength value tables. Tests were to be performed on other sizes of Southern Pine lumber by July 2012. Here is the latest update.
The news is better from the July 19 2012 meeting of the Southern Pine Inspection Bureau (SPIB) according to a report from the Structural Building Components Association.
The test results for 2×6, 2×8, 2×10, and 2×12 Southern Pine lumber have been gathered and are being reviewed. The preliminary reports state that the results for 2×6 size lumber are reportedly similar to 2×4’s. However, the other sizes reportedly showed a show a reduced bending strength value of “only” 15% for Select Structural grade, 20% for #1 grade, and 25% for #2 grade. The modulus of elasticity, which affects the deflection or sag of the member, was reportedly found to be 5% lower for #1 and #2 grade. Shear strength values were not tested, and thus, remain the same. After further review of these results, new strength values will be recommended.
Our thanks to the Structural Building Components Association for keeping on top of this issue for us.