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July 2021 #13264 Page #82
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The Use of Non-Typical Lumber Grades
n our January 2021 issue, Frank Woeste and Don Bender wrote, “Hybrid Lumber” Grade Stamps Require Special Attention. This article provided information on how to recognize hybrid grade marks and how to calculate hybrid lumber values for truss design. Included was this caution:
A hybrid product grade mark indicates a mixture of species groupings and/or regions, requiring careful consideration of design values. For each design value, the lowest of the mixture must be used. This includes strength and stiffness values, along with the specific gravity. Specific gravity is especially important as it influences truss plate gripping values, unit shear capacities for diaphragms and shear walls, and hold-down capacities for shear walls.
In our May 2021 issue, we were pleased to provide an update on the situation, made available by the American Wood Council (AWC), New Table 4G in NDS Supplement – Multi-Species and Country Grademarked Lumber. This included the following from AWC’s WoodPost: To help designers and code officials navigate this relatively new approach to grade marking, the lumber grading agencies, working with the American Lumber Standards Committee and AWC staff, have developed a new table of design values for multi-species lumber grade marks. This new table, entitled Table 4G, Reference Design Values for Multi-Species and Country Grademarked Visually Graded Dimension Lumber (2”-4” thick), has been approved and included as an addendum to AWC’s 2018 NDS Supplement. For an extensive number of multi-species grade stamps from various countries, including some North American multi-species groupings, the table provides the lowest design values among the combined species for each design property (and therefore the appropriate single set of design values to be used with the grade stamp). Users of this table will no longer have to check the design values for each included species indicated by a multi-species grade stamp to determine the minimum values for each design property. The new Table 4G can be viewed and downloaded here. In mid-June, the use of European lumber came in question in North Carolina following a press release by the NC Dept. of Insurance (NCDOI): N.C. Building Code Council warns of the use of European lumber in North Carolina. That statement was met with responses by AWC and the Pacific Lumber Inspection Bureau— both of which are included on the following pages. It is expected that NCDOI will be issuing a revision to its opinion, which we hope will further clarify the proper use of this non-typical lumber. Continued next page
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