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Don’t Forget! You Saw it in the
Adverti$$er
December 2020 #12257 Page #37
Who is Responsible for Lumber Quality in Your Trusses?
By Glenn Traylor
here are many steps in the process of bringing lumber to the truss plant to be used in our trusses. Lumber must be harvested then sawn. Drying and planing brings the lumber closer to potential use, but it is not until the lumber makes it through the grading process that it is suitable for use. Sometimes the lumber is reviewed by inspectors to make sure visual inspecting and/ or machinery is accurately qualifying the lumber. In the photo, the lumber grader is remarking lumber that has been upgraded because the optical machinery judged some darkness in the lumber as knots larger than the grade allowed. With a visual re-inspection, the knots are within the upgrade and can be used appropriately. Is “Too bad the truss plant can’t upgrade lumber” what you are thinking now? “Where do I get one of these stamps?”
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Am I right? Well, you cannot upgrade, but you can and should evaluate the lumber for suitability for your use in the truss at hand. Just because it meets lumber grades does not mean it meets your needs. There are several items that might make the lumber unsuitable while still qualifying for the grade as marked. Here are some of the issues we might run into on a regular basis. 1. Wane that meets grade may be in a location that will impact connector installation and affect the required tooth count. 2. Mill cuts, while allowed in grade, are not suitable for member applications, especially chords subject to bending forces. 3. Crooks that meet grade for the length of the inspected lumber sometimes change when cut to shorter lengths. Cross cutting does not change the grade of the lumber once it’s initially graded, but it might change suitability due to the defect location in the shorter piece. 4. Visual defects that meet grade might not meet your client’s criteria. Just because it meets grade does not mean it meets the impression the defect might imply. An example would be missing knots or holes in the lumber.
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