On a recent trip to Japan to observe construction manufacturing methods, I was struck by the amount of time a plant manager spends on the production floor. Comparing this Japanese methodology to our truss industry, our plant managers and upper management spend relatively little time engaged in this portion of our responsibilities. A potential consequence of this separation is its effect on company culture. Culture is created from the top, and management needs to be engaged.
Weekly inspections by your in-house inspector are not the only way to monitor and improve quality. A walk-through in conjunction with a safety walk-through should be done on a regular basis by management and supervisors. Is this walk-through of any value? Yes! If you know what to look for, walk-throughs are very valuable. Besides engaging your production workforce, your feedback is important. You don’t have to carry paperwork around with you, nor do you need to stop or delay fabrication, but you do need to use your eyes. So, do you think you know what to look for?
Test Your Skills
To see if you are ready to take the challenge, and to illustrate your skills, examine the following photographs. What do you see? What do you look for? For each photo, decide if the situation is acceptable or not. What is the reason for the violation? Is it something that should be addressed?
[See PDF or View in Full Issue: Figure 1. First splice example; Figure 2. Second splice example; Figure 3. Floor truss in machine; Figure 4. Stacked trusses on the rack; Figure 5. Trusses coming off the finish roller; Figure 6. Trusses neatly stacked after finish roller; Figure 7. Joints after pressing, showing joint gaps; Figure 8. Plate shadows]
The splice in Figure 1 looks like it might be a problem, with our attention brought to the plate placement. Usually splices are totally covered, because essentially they are the critical part of the joint. In this situation, the plate looks wrong—but, if you look at the shop drawing, the plate is correctly placed. The truss builders were following the design!
The situation in Figure 2 looks the same as Figure 1. The splice is not covered by the connector. When this is compared to the shop drawing, however, the plate design covers the splice. This connector needs to be removed and replaced with a larger connector. Remember, a larger size is always required because of the reduction of tooth holding when a plate is removed and replaced. (For additional information, see my article, “Is there a reduction for plating in a previously plated area?’)
In Figure 3, the eye catches the darkness of the member. Closer inspection indicates heavy wane in the plated area. Where wane exists (bark or insufficient wood at the corner or along the edge due to the curvature of the log), there is no plate holding or force transfer. The wane creates a joint as if the connector teeth do not exist. Particularly in floor trusses where there is a very limited amount of real-estate to connector, the members space is a premium. Often these situations cannot be repaired with a larger connector plate. Where more than half of the face is missing, the member should be culled and replaced. In this example, workers need to be trained to deal with this normal occurrence effectively, and well before it gets into the truss product.
In Figure 4, finished trusses are stacked as they come off the roller. Each truss is stacked beside the other. The object that should catch the eye is the lack of similarity. The second truss from the inside has an extra connector. Upon careful examination, it looks like the builders have repaired the chord with a couple of connectors on each side of the break of the member. This repair is not acceptable without specific engineering. The workers need to be trained to replace lumber rather than make their own repairs. (For additional information, see my article, “Is this an allowable repair?”)
In Figure 5, the issue we see is the lack of symmetry. The truss plates do not line up with the front and back sides of the truss. In this case, the connector exceeds the profile of the truss. This is never acceptable. When this happens and makes it to the jobsite, framers attempting to fix the problem can damage the connector or, even worse, create an unsafe situation by removing parts of the connector or removing the connector completely. Beating the edge of the connector with a hammer also causes many issues, including creating surface defects that can impact the integrity of the joint. These field repairs need to be done under the supervision of a qualified person. Cutting the connector along the protrusion is rarely an acceptable method and needs evaluation as to the appropriateness of this action. The best situation is to prevent this from occurring in the first place. [Point of perspective: There are times when an engineer has designed a situation in which the connector can/will be cut or modified. These situations always require specific engineering and special attention should be paid to them during production.]
In Figure 6, the trusses are stacked neatly, but the casual eye catches the lack of uniformity. In this situation, the trusses are built correctly. The trusses vary because the designs vary. A careful examination was made to insure accurate construction.
In Figure 7, the eye is drawn towards the darkness of the four tooth slots. This can indicate joint gap. This is a red flag. In this situation, upon careful examination, the joint does have member gap issues and must be evaluated for repair. (For additional information, see my article, “Mind the (Member) Gap.”)
In Figure 8, look for plate shadows. Shadows indicate a potential plate embedment issue. When this occurs, take a gauge and measure the embedment gap between the lumber and the plate. A plastic credit card works well. If the card fits under the plate and it is tight, then it is likely okay but could indicate adjustment might need to be made. If the card fits under the plate and is loose, the truss needs to be repressed. (For additional information, see my article, “How Important is Embedment,” and refer to ANSI/TPI 1 for the provisions that allow for some gap.)
Tabulate Your Results
So, how did you do? If you said Figure 1 and Figure 6 are correct and the others are wrong, give yourself an A+. While it’s sometimes difficult to see in photos, many of these illustrations are much easier to see in person. The message of the story is: don’t just depend on your ANSI/TPI-compliant in-house inspections. A quality walk-through can be done in conjunction with a safety walk-through, because both are important for your business and your workers. Weekly inspections by management are the best way to monitor your program—so be sure you know how to look.
Glenn Traylor is an independent consultant with almost four decades of experience in the structural building components industry. While he is a TPI 3rd Party In-Plant Quality Assurance Authorized Agent covering the Southeastern United States and performs 3rd party safety auditor services, these articles represent his personal views, knowledge, and experience. Glenn serves as a trainer-evaluator-auditor covering sales, design, PM, QA, customer service, and production elements of the truss industry. He also provides project management specifically pertaining to structural building components, including on-site inspections and ANSI/TPI 1 compliance assessments. Glenn provides new plant and retrofit designs, equipment evaluations, ROI, capacity analysis, and CPM analysis.