The APA Help Desk and some APA regional field representatives have noted an increased number of inquiries about availability of Structural I panel sheathing from areas (e.g. north eastern U.S.) that would not typically be considered active markets for Structural I sheathing. As a specialized structural panel, Structural I sheathing has not commonly been readily available in all market regions.
Unfortunately 2009 IBC (in at least the first and second printings) TABLE 2306.3 WOOD STRUCTURAL PANEL SHEAR WALLS unintentionally omits several panel thicknesses (3/8, 7/16, 15/32 and 19/32-inch) from the Sheathing, plywood siding except Group 5 Species panel grade section. This unintentional omission is acknowledged by ICC staff and an errata is in the works.
APA has updated the APA System Report: Design for Combined Shear and Uplift from Wind, Form SR-101. This publication provides designs for utilizing wind uplift resistance capabilities from wood structural panels. The updated report also includes information on resisting lateral shear forces and wind pressure perpendicular to the wall.
The APA Publications Index, Form B300 NN, has been updated. The revised 2008 index provides a complete listing of APA design and construction guides, product guides, builder tips, case histories, industrial publications and other materials available from the Association.
Answer: The Cd factor recognizes that as a structure deforms, the actual response of the structure deviates from the deformation model due to the non linearity (plastic response) of the system. Structural materials like masonry systems are rigid and have very low Cd factors because they have little plastic behavior. Ductile systems like wood shear walls and steel moment resistant frames have very high Cd factors because they are expected to have a large “plastic region” in their deformation curves.
APA just issued the 2007 Engineered Wood Construction Guide, the major reference manual for using engineered wood products in residential and commercial construction.
In response to growing acceptance by the building community for the use of wood structural panels in combined shear and uplift, some manufacturers of competing products are struggling to come up with a case to promote the use of their products. For example, Simpson Strong-tie published a Technical Bulletin in September titled, Understanding the Performance of Wall Sheathing Used to Resist Simultaneous Uplift and Shear Loads, in which it discourages use of the wood structural panels system for combined shear and uplift. The bulletin raises a series of issues when using this system.
It is important to note that International Code Council Consensus Committee on Hurricane Resistant Construction (IS-HRC) heard the same arguments, as did the Institute for Business and Home Safety (IBHS). When balanced by the analytical procedures used by APA and full-scale testing conducted by Clemson University and the National Association of Home Builders (NAHB), neither group was convinced by the validity of the arguments.
I am pleased to provide the first blog entry on a new project I have been working on since December 2005. In early 2006, APA expanded the Research Center to include a significant amount of storage space. As with most of the engineers at APA, when new “space” is available, we always try to make the space multi-use, and if possible, increase the testing capability of the Research Center.
As part of this lab expansion, we added a specially designed concrete slab and accompanying hardware that can load full-scale three-dimensional structures with lateral loads.
Last month, five members of the APA technical staff presented papers at the 9th World Conference on Timber Engineering (WCTE), held this year in Portland, Oregon. This five-day conference featured over 300 presentations by wood industry professionals and was a great opportunity to discuss and learn about the latest technological advances, research and design in timber engineering.
Several years ago, I received numerous inquiries about the difference between toenails and slant nails. At the time of this inquiry, we developed Technical Topic: Slant Nailing, Form TT-058. This blog entry is intended to briefly discuss the subtle differences between these two nailed applications.
Question: What is the appropriate axis of APA Rated Sheathing (OSB or plywood) applied as wall sheathing to studs?
Answer: APA RATED SHEATHING panels with roof Span Rating of 24 inches or greater may be installed with the long dimension (or strength axis) either parallel or perpendicular to studs 16 or 24 inches o.c. The exception is 3-ply plywood panels used as nailable sheathing, which must be applied with the long dimension across studs when studs are spaced 24 inches o.c.
