Designing, installing per code compliance /
By Jane Martinsons NFBA staff writer /
As post-frame construction continues to move into larger agricultural structures, and into the commercial market, it is imperative for those who design and build trusses to stay abreast of and compliant with codes and regulations. “This is particularly important when installing metal-plate-connected wood trusses spanning 60 feet and greater,” said Ken Guffey, PE, general manager of Rigidply Rafters, Inc., Richland, Pa., a truss manufacturer that serves a large section of the East Coast.
Rigidply Rafters photos
“Buildings should be designed correctly by someone who knows what they’re doing,” Guffey told members of the National Frame Building Association when he spoke at the Frame Building Expo in St. Louis last year. “Every day, having a design professional is becoming a much more important part of what we’re trying to do in the post-frame industry.”
Post-frame construction with wide-span trusses
Why focus on wide-span trusses? “First, liability concerns and problems tend to grow with the size of the truss,” Guffey said. “When you swing big trusses, things are different because of resulting installation and bracing requirements. Wide-span trusses often maximize the capacity of the crew, and of the wood and metal plates in the truss. What you do has a big impact. Obviously, forces are bigger (with wider trusses). The components weigh more and the impact of an accident is much greater.”
It’s also vital for the post-frame industry to maintain a good reputation as it expands into new markets. Recalling the heavy damage sustained by post-frame structures during a powerful Eastern snowstorm in early 2009, Guffey said every effort should be made to follow regulations and to use quality materials in post-frame structures, which are inherently economical.
Guffey, along with Tim Riegel, PE, engineering manager at Rigidply Rafters, recommended several sources on current codes and regulations, including Building Component Safety Information Guide to Good Practice for Handling, Installing, Retraining and Bracing of Metal Plate Connected Wood Trusses, produced by the Structural Building Components Association and the Truss Plate Institute, and Truss Technology in Buildings by the Wood Truss Council of America, Inc.
After briefly reviewing the 11 chapters of the BCSI guide (B1—B11), Riegel said, “60-ft trusses are a totally different animal, so hook up with someone with experience to protect both your company and your employees. You need to know what you’re doing.”
In an earlier Post-Frame Advantage article, wood engineers Frank E. Woeste, PhD PE, and Donald A. Bender, PhD PE, urged registered design professionals (RDPs) who specify long-span wood trusses for post-frame buildings to take special note of recent changes in the 2009 International Building Code and the ANSI/TPI 1-2007 truss design standard.
Owners of a project with metal-plate-connected wood trusses spanning 60 feet and greater are now required to engage an RDP to design and inspect both temporary and permanent bracing for trusses (See IBC Sections 2303.4.1.3, 1704.6.2, and 1704.1.)
For more information, refer to their article, “Wood Truss Bracing Rules Updated,” in the May 2011 issue of Construction Specifier magazine.