Whether you’re a novice or a seasoned professional, there’s always more to learn, especially as construction practices continue to evolve. That’s why our colleagues at Virginia Tech are pleased to be able to offer continuing education each spring. In addition, for many course topics, related publications are available for self-study, too.
Advanced Design Topics in Wood Construction Engineering
This year, 7 of 12 course units in our Virginia Tech program have significant truss design content for component manufacturers and truss designers. For example, the following should be of particular interest.
Balcony Design – IBC Changes and Wood Protection Considerations
Cantilevered balconies have limited structural redundancy and, as such, require special attention by design professionals and other parties involved in the construction process. In addition to reviewing the 2018 IBC balcony provisions that were motivated by the 2015 Berkeley balcony collapse, “good practice” design measures for redundant protection of the wood-framing in-service will be presented.
Investigation of Wood Floor Failures Under Dynamic Loading
In the aftermath of the widely publicized “Clemson” floor collapse and other similar floor collapses, designers and suppliers are seeking answers as to why the failures are occurring and how they can be avoided. Preliminary results of a WSU research study will be presented that include a survey of floor collapse cases in the U.S. and related dynamic load research information.
Information on all 12 course units is available on the VA Tech website at http://www.cpe.vt.edu/woodcon/index.html.
Self-Study and Continuous Learning
Furthermore, we encourage you to undertake self-study if you’re not able to join us this May in Blacksburg, VA. Regarding our course unit on Balcony Design – IBC Changes and Wood Protection Considerations, several versions of the subject have been published. The April 2019 issue of The Advertiser includes this article, “IBC Balcony Changes Spur “Best Practice” Design Recommendations.” Likewise, the Fall 2019 issue of Licensed Architect includes the article, “Balcony Design – IBC Changes and Wood Durability Considerations.”
Having reviewed one of the balcony articles in self-study, a practical question might be—is the subject matter presented possibly important to what I do, or maybe a design option that a customer may want to consider?
Regarding exposed balcony framing design, we recommend using UC4A, UC4B, or UC4C pressure-treated wood (and appropriately protected fasteners) even when an impervious moisture barrier system is required per the 2018 IBC. In the interest of life-safety, the redundant protection against decay is reasonable given the limited structural redundancy of a free-end cantilever balcony system. Redundant protection against decay of a free-end cantilevered balcony should be in the interest of the Owner, Architect, and General Contractor.
In addition to the 2018 IBC requirement for an impervious moisture barrier system, cross-ventilation of each separate space of enclosed balcony framing is required:
“2304.12.2.6 Ventilation beneath balcony or elevated walking surfaces. Enclosed framing in exterior balconies and elevated walking surfaces that are exposed to rain, snow or drainage from irrigation shall be provided with openings that provide a net free cross-ventilation area not less than 1/150 of the area of each separate space.”
It can be noted that wood truss framing can easily accommodate the IBC cross-ventilation requirement. Architects and General Contractors may find truss framing desirable as it adds flexibility to their ventilation design options.
As a reminder for truss designers, if the project design professionals specify pressure treated (PT) lumber (UC4A, UC4B, or UC4C) for enclosed balconies in addition to an impervious moisture barrier system per the 2018 IBC, the truss plates used for the joints that include PT lumber should be stainless steel because of the corrosion potential of the variety of PT chemicals used for the treating process. Also, the wet-use factor for “gripping values” would apply (absent the use of Kiln Dried After Treatment, or KDAT lumber).
No matter how much we know, there’s always more we can learn. Consider expanding your knowledge on these topics or others that interest you.
About the Authors
Frank Woeste, P.E., Ph.D., is Professor Emeritus, Virginia Tech, and frequently consults with the building designers and code officials on various aspects of wood construction. Frank, along with his colleagues, continues to offer continuing education courses at Virginia Tech.
Don Bender, P.E., Ph.D., is Weyerhaeuser Professor of Civil Engineering and Director of the Composite Materials & Engineering Center at WSU–Pullman. He is an expert in testing, design, and construction of timber structures. Don teaches university and outreach courses in structural engineering and is active in national building code and standards development.