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Component Manufacturing dverti$er
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Don’t Forget! You Saw it in the
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June 2019 #11239 Page #56
Adverti$er
The Critical Job of Truss Builders
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ast month’s fine article by Glenn Traylor, “How Do I Choose Which Plates for a Critical Plate Inspection?”, reminded me of investigative experiences I’ve had throughout my career. The work of truss builders is extremely important, as evidenced by instances of truss failures.
Along with permanent bracing deficiencies, the most common cases of plating error that I’ve seen have been W-trusses clear spanning about 50-ft. As Glenn discussed, a common thread for the peak joint misplacement issue occurs when the top chords are 2x6 (and greater) with 2x4 webs. Apparently, truss builders may (improperly) shift the plates upward in an attempt to “cover” more of the larger top chords.
Truss Fabrication Quality—A Life-Safety Issue In one case involving a fatality during truss installation, a 2x6 36-ft Fink truss (2-ft. on-center) failed at the peak joint when an installer was standing on the center panel of the bottom chord. The truss design drawing required 5x8 plates to be centered on the intersection of the four members at the peak joint. As shown in the photo, the 5x8 plates were improperly shifted upward onto the 2x6 chords about 1-1/4 inches. In addition to the plate misplacement issue, the teeth in contact with the webs area were not fully embedded, exacerbating the misplacement error. For the truss cases I’ve investigated, this case was the easiest to diagnose because photographic evidence taken before the collapse showed that temporary truss bracing (both lateral and diagonal per industry recommendations) had been installed. A combination of plate misplacement and partial plate embedment caused a fatality during roof truss installation. PHONE: 800-289-5627
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