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.

Ready availability of Structural I has historically been most common in regions dealing with high seismic design requirements. We suspect that the cause for the unexpected increase in Structural I specifications may have to do with a typographical error in the 2009 IBC which unintentionally omitted rated sheathing from TABLE 2306.3 WOOD STRUCTURAL PANEL SHEAR WALLS. See our previous blog entry for additional information.