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Cold-formed is hot: Straight lines, heavy load handling mark CFS truss benefits

As the construction industry undergoes varying changes due to building code and market shifts, many general contractors, subcontractors and truss installers are finding themselves crossing the boundaries between the conventional wood framed projects and continually increasing cold-formed steel projects. For many, CFS projects represent new territory, offering varying challenges that are unlike those found on the average wood-framed project. One such challenge relates to roof trusses: The proper handling of the CFS truss package is an important factor on the job site.

Handle With Care

Most individuals involved in the truss industry have read the available general guidelines for the safe handling of trusses. The Cold-Formed Steel Council, Madison, Wis.; Cold-Formed Steel Engineers Institute, Washington, D.C.; and similar organizations have provided documents to the industry that have proven to be excellent tools in the safe erection of truss systems, helping to minimize job-site mishaps.

As thoroughly as the available guidelines may be followed, fabricators and contractors alike must also utilize their common sense when it comes to handling CFS trusses. “Safe” handling, in accordance with accepted industry guidelines, does not always keep truss members from being damaged; that’s where “proper” handling and the use of common sense comes into play.

Roof trusses, be they metal plate connected wood or CFS, are designed for strength in the vertical plane. Loads or stresses are dispersed throughout the truss so that one member is not taking the full strain. You’ve heard the expression, “a chord of three strands is not easily broken.” This analogy may be applied to the truss, as its individual components work together to fulfill their purpose. When hung, a rope or “chord of three strands” easily may be ascended, utilizing its inherent strength to withstand the force applied; however, when strung in the horizontal, a rope will bow as loads are introduced, regardless of how taut it may be pulled. Likewise, forces applied to a truss in the vertical plane are dealt with as one unit. The flip side is that loads applied to the face of a truss are taken on by individual members that, if damaged, could cause the entire unit to perform poorly. When handling a truss, one must be aware of the nature and position of the applied stresses during loading, unloading, moving around the job site or storing. Workers must properly position straps or supports in such a way as to minimize the possibilities of damaging any single member of the truss unit.

The common-sense answer to reducing CFS truss member damage is in the use of blocking materials. Though it may take an extra minute or two to add a block when preparing to handle a truss with straps, it will save in the long run, as unnecessary repair work can be avoided. Properly placed blocking over storage supports also aids in avoiding damage to individual member sections. As most job sites end up with a scrap pile containing small but usable materials, there is almost no added cost of materials in ensuring a common-sense approach to properly and safely handling and storing CFS trusses.

Understanding Weakness

Another important aspect of proper CFS truss handling is to keep the truss storage area free from job-site traffic to avoid accidents. When storing the CFS truss horizontally (the preferred method), refrain from stacking building materials and/or walking on the truss face. Remember, a CFS truss is much like an egg, in that it may withstand tremendous force when squeezed end to end, yet fails when squeezed at the sides. Given that a truss is designed to support forces in the vertical plane, common sense dictates that the lateral plane is the Achilles’ heel of the truss. This is why the industry guidelines for construction and permanent bracing have been so thoroughly documented and must be followed to ensure that the all-important roof system remains stable.

Added Benefits

As traditional wood-framing contractors expand their horizons and embark on a journey into the CFS industry, they will find the addition of CFS trusses to be a positive mark on the image of their companies. CFS truss designs are now utilizing a variety of proprietary shapes in place of the standard C-stud. The value engineering of such designs results in simplified installation and decreased labor factors, reducing the overall project costs. Erectors also will enjoy installing a true and straight CFS truss as opposed to potentially twisted and warped wood trusses.

Furthermore, as time passes and changes to the roof system may be required, the CFS truss is 100 percent recyclable.

Though a learning curve may exist for handling CFS trusses, utilizing CFS in place of traditional wood is good common sense.

Jamie L. Walton is the technical sales representative for Aegis Metal Framing LLC, Chesterfi eld, Mo. For more information, visit www.aegismetalframing.com.