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JAS Dimension Lumber Standard Revision Defends NA Species Group Strength Properties

Hidehiko Fumoto

By Hidehiko Fumoto

Deputy Director and Manager Technical Services, Canada Wood Japan

September 3, 2014

JAS Dimension LumberAs we reported previously, new Japanese species groups have been proposed for the first time in the JAS600 revision committee; the Japanese Agricultural Standard for dimension lumber. During the course of the revision committee the FFPRI1) had proposed new design stress values which were unrealistically inflated for Japanese species; some of those proposed were even higher than for DFir (N).  With the help from Dr. David Barrett, Professor Emeritus of UBC and an in-grade test authority, COFI demonstrated to MAFF2)/FFPRI that the proposed values for Japanese species should have been significantly reduced with the use of a “Grade Quality Index (GQI)”, which is the internationally recognized concept designated in ASTM D 1990.  This lobbying activity appears to have been successful.  On August 26th, a JAS Council meeting took place at MAFF to finalize the JAS600 revision.  In this meeting, the committee concluded that the revision draft should be approved with FJ bending strengths which are identical to what COFI counter-proposed with the including of the GQI for the visually graded lumber.  Usually, MLIT3) assigns design stresses after the establishment/revision of the forest product JAS standards.  However, this JAS600 revision is integrating FJ dimension lumber standard, where FJ bending strength requirement is being incorporated.  The values in this requirement should basically be identical to the bending design stresses that MLIT assigns for visually graded dimension lumber.  Therefore, this time the JAS revision governs the entire procedures of assigning design stresses that only MLIT should have been responsible for.  As the JAS600 revision went preferably, it is anticipated that MLIT is following our proposal when they assign the design stresses.  The MLIT’s final process of designating the design stresses is scheduled within this fiscal 2014.


1) Forestry and Forest Products Research Institute

2) Ministry of Agriculture, Forestry and Fisheries

3) Ministry of Land, Infrastructure, Transport and Tourism