As a follow-up to our January 2021 All Things Wood article by Frank Woeste and Don Bender, “Hybrid Lumber” Grade Stamps Require Special Attention, we are pleased to report that additional information is now available for designers and code officials.
The following article appears in the April 19, 2021 edition of the American Wood Council’s WoodPost.
New Table 4G in NDS Supplement – Multi-Species and Country Grademarked Lumber
AWC’s January edition of WoodPost featured multi-species grade stamps that require the designer to check each specie's design values and use the lowest design value among the different species for each design property. These new multi-species grade marks are the result of certain mills producing lumber from two or more species without separating them in production. Lumber with these grade stamps could be any of the species and countries shown on the grade mark. To review that WoodPost information, go here.
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.