APA Blog for Professional Associates - Shear Walls

Unexpected Increase in Structural I Sheathing Specifications

Wed, 12 May 2010 08:40:00 -0700

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.

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Typographical Error in 2009 IBC Wood Structural Panel Shear Wall Table 2306.3

Tue, 11 May 2010 14:29:00 -0700

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.

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Design for Combined Shear and Uplift from Wind

Mon, 01 Feb 2010 16:23:00 -0700

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.

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2008 APA Publications Index Now Available

Thu, 17 Apr 2008 15:15:00 -0700

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.

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Question: What is the Cd factor in seismic design in the new ASCE-7?

Tue, 05 Feb 2008 15:50:00 -0700

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.

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New Engineered Wood Construction Guide

Mon, 08 Oct 2007 10:05:00 -0700

APA just issued the 2007 Engineered Wood Construction Guide, the major reference manual for using engineered wood products in residential and commercial construction.

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Using Wood Structural Panels for Combined Shear and Uplift

Fri, 10 Nov 2006 08:59:00 -0700

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. [More]

APA Introduces Full-Scale House Test Project

Tue, 07 Nov 2006 15:33:00 -0700

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. [More]

APA Presents at 2006 World Conference on Timber Engineering

Fri, 08 Sep 2006 11:57:00 -0700

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. [More]

Slant Nail Connections

Fri, 18 Aug 2006 12:28:00 -0700

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. [More]

Help Desk Question: Should Wall Sheathing be Installed Horizontal or Vertical?

Tue, 01 Aug 2006 12:11:00 -0700

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. [More]

Using the species adjustment factor with staples

Tue, 20 Jun 2006 14:04:00 -0700

I recently had a discussion with some fellow engineers about the species adjustment factor in shear wall tables using staples in the International Building Code. When determining the allowable shear for wood structural panel shear walls, IBC Table 2306 footnote (a) requires adjusting the Structural I capacities for staples, using a flat adjustment of 0.82 for most framing species (those with a specific gravity of 0.42 or greater) or 0.65 for others. The footnote also requires adjusting the shear values for the framing with nails and the type of sheathing used based on a formula of (1-(0.5-SG)) but not more than 1.

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Shear wall values for grooved siding products

Fri, 02 Jun 2006 12:01:00 -0700

All three of the major model building codes and the International Building Code recognize the use of APA 303 Plywood Siding (such as T1-11) for use as shear walls. Panel siding products usually feature grooves and ship lap edges, which leads to the question: does differing thicknesses of the panel affect allowable shear wall values?

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Confused by IBC reference to LRFD in ASD section

Thu, 25 May 2006 10:44:00 -0700

A structural engineer recently asked me about a confusing section of the International Building Code (IBC) and its references to Allowable Stress Design (ASD) and Load and Resistance Factor Design (LRFD). In 2003 IBC Table 2306.4.1, the allowable shear values are for ASD, as section 2306, where the table is located, pertains only to ASD. The confusion stems from footnote h, which refers to shear values of 490 plf (LRFD) and 350 plf (ASD). As this is an ASD table only, the mention the 490 plf LRFD number in the footnotes was confusing. Fortunately, the 2006 edition of the IBC has removed the confusing footnote and will just refer to the 350 plf. [More]

Nails vs. screws for sheathing applications

Tue, 23 May 2006 09:08:00 -0700

A builder looking for the best possible way to secure sheathing for sub-floors recently asked if screws could be used in place of nails, and whether screws would provide better performance.

APA finds that glue-nailed floor systems perform quite satisfactorily and thus does not have recommendations for fastening structural panels to framing or supports with screws. This is not to say, however, that appropriate structural screws intended for wood assembly should not be used.

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