Are Roof and Floor Trusses the Only Components that Need a Quality Assurance Program?

Roof and floor trusses are important components that need special consideration to insure their correct manufacture. Components built to the IRC and IBC require the manufacturer to adhere to specific requirements. These requirements provide a blueprint to facilitate the manufacturing of a quality product. The program is enumerated in Chapter 3 of the ANSI/TPI 1–2014. Compliance requires a 3^rd party to monitor and audit the program, so purchasers, specifiers, and inspectors have some confidence the product is being produced correctly.

Wall panels are also important components. While they tend to be less complicated and less varied than roof or floor components, they should be manufactured following the designer’s directions. Following the success of the Chapter 3 Quality Assurance Program (QAP), wall panel manufacturers can follow a path similar to that used with truss components.

Several elements should be considered when determining what a wall panel program should include. One example is the excellent program for wall panel quality assurance available with the WTCA Wall Panel QC program which, as shown in the photo, facilitates a comprehensive review of product production.

It should be noted that, while not specifically required, some municipalities can require code compliance inspections and/or 3^rd party monitoring and audits. A 3^rd party program can eliminate expensive site visits, provide an industry standard, improve marketability, reduce call backs and rebuilds, and reduce overall product liability as part of a good risk management program.

Just like trusses, the most important aspect of a strong program relies on the design information. A shop drawing or specification is required in order to provide the inspector the component requirements. Often the shop drawings do not contain all the necessary information. This should be supplemented by providing a standard and referencing this standing within the shop drawing. Since a simple, concise standard like Chapter 3 doesn’t exist for wall panels, a standard should be developed using building code requirements. Although code requirements can vary from region to region, several elements should be included in all cases.

1. Specific dimensions need to be clearly defined including tolerances.
    
2. Squareness should be verified also providing tolerances. These can vary with panel size or can be an exact limit.
    
3. Material verification should be clearly defined. A record of grade marks on the inspection shows compliance and illustrates upgrading, downgrading, or substitutions.
    
4. Header material verification and lengths within tolerances should be recorded.
    
5. Locations of subcomponents, tees, jacks, interior ladder panels, etc. need to be verified and their locations need to be confirmed. Tolerances should be clearly defined.
    
6. Stud placement should be verified relative to bottom and top plates.
    
7. Nail attachment of components and subcomponents should be verified and recorded. This is a code-specific requirement and can be subject to wind, seismic, or load transfer conditions. The shop drawing or the drawing and a supplemental guide should provide the requirement, including gauge, length, spacing, minimum, and maximum limits.
    
8. Sheathing is often applied at the plant and should be part of the inspection process. Nail embedment (refer to photograph), over nailing, edge distance, edge distance in addition to gauge, type, and length should be compared to the shop drawing and specification.
    
9. Edge nailing and field nailing can have different values. This must be measured and a record of the actual spacing should be documented. Some regions require a nail count per square foot, an average. Some have a minimum and maximum spacing value.
    
10. Attaching sheathing requires accurate location of stud, jacks, and components so material is nailed in the most ideal location, usually in the center of the member. While the center is not always possible, the inspection of “shiners” should be made to determine if counted fasteners are actually embedded. This requires the inspection of both sides of the panel.
     
11. Components should be inspected for splits and cracks. Excessive cracks can degrade the effectiveness of the component and should be repaired and monitored. The photo illustrates split plates that can occur if nailing is not managed correctly.

Observing these suggestions will help ensure that your wall panel manufacturing process will produce the high-quality products that you, and your customers, expect.

Glenn Traylor is an independent consultant with almost four decades of experience in the structural building components industry. While he is a TPI 3^rd Party In-Plant Quality Assurance Authorized Agent covering the Southeastern United States and performs 3^rd 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.