APA Introduces "Standard Factors for OSB Equivalency" Concept
Originally published by the following source: SBCA — July 26, 2018
On January 3, 2013, SBCA attended a meeting with APA to address overstated OSB design properties in the building code. Mr. Ed Elias, President, APA Board of Directors and attendee of the meeting, responded with a letter where he discusses the concept of “standard factors” for “product equivalency.” Specifically, he wrote:
"APA staff has reviewed the information that was shared with us and we have the following comments and concerns:
We believe that a major goal for the SBCA position is to provide a cost-effective engineering solution to their membership and as such this goal serves the SBCA membership well. However, by establishing standard factors in which product equivalency or system performance are applied generically, an unintended consequence may be that non-wood products (e.g. foam sheathing) gain an advantage and supplant traditional OSB market share.
This is not in our Association member’s best interests..."
Summarizing the key points in the letter from Mr. Elias:
- SBCA desires to provide its members with a cost-effective engineering solution for wall panel performance.
- SBCA desires to provide a level playing field for alternatives to OSB so that they can cost-effectively compete with OSB’s overstated design values.
- SBCA’s approach has an unintended consequence that, “may be that non-wood products (e.g., foam sheathing) gain an advantage and supplant traditional OSB market share.”
- APA does not support SBCA’s approach because it, “is not in our Association member’s best interests.”
It seems reasonable to assume APA will take action to protect its competitive advantage in the market in any way that it can, particularly if someone uses SBCRI tested and developed “standard factors for OSB equivalency” in the market in order to compete with OSB on a level playing field basis.
Since 2009, the Structural Building Components Research Institute (SBCRI) has conducted a wide variety of OSB tests (more than 170 discrete tests), and consequently knows OSB tested performance well. This testing has been done to thoroughly understand OSB performance and to establish the standard factors for OSB equivalency Mr. Elias refers to in his letter. As Mr. Elias recognizes, the goal of SBCRI testing and analysis work is to level the structural sheathing playing field, advance a free and fair market and tend to the best interests of SBCA members and all others buying and specifying these types of products.
SBCRI’s test analysis was thoroughly discussed with APA on January 3, 2013. At that time SBCA gave APA all the information included in the following table:
| SBCRI Testing | Sheathing Thickness & SPF Stud Spacing | Nail Type and Spacing | Tested Strength (PLF) | IRC/IBC Defined Strength (PLF) | Standard Factor for Product Equivalency |
| IRC Section R602.10 (Tables R602.10.3(1) through R602-10.3 (4)) Testing of OSB Braced Wall Panel without Gypsum | 3/8, 7/16 & 15/32" @ 16" o.c. | 8d Galvanized box nail (0.113" x 2-1/2") or 8d Common (0.131" x 2-1/2") | 350 | 6001 | 1.7 |
| IRC Section R602.10 (Tables R602.10.3(1) through R602-10.3 (4)) Testing of OSB Braced Wall Panel with Gypsum | 3/8, 7/16 & 15/32" @ 16" o.c. | 8d Galvanized box nail (0.113" x 2-1/2") or 8d Common (0.131" x 2-1/2") | 450 | 8401 | 1.8 |
| IBC Section 2305.1 and 2306.3. Testing of OSB Segmented Shear Wall with Hold Downs | 3/8, 7/16 & 15/32" @ 16" o.c. | 8d Galvanized box nail (0.113" x 2-1/2") or 8d Common (0.131" x 2-1/2") | 500 | 6712 | 1.3 |
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1. Basis of IRC wall bracing tables. For details on how the IRC bracing tables were developed, see the Wood Design Focus article by Crandell and Martin, 2009 |
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Further, SBCA introduced code change proposals to level the playing field for all sheathing products. APA and the American Wood Council (AWC) have opposed these efforts every step of the way. Why? It does not serve their membership’s best interests (for a listing of members see (APA) and (AWC).
It is ironic SBCA’s efforts are based off of APA’s own approach. APA has used standard factors for OSB equivalency to create design properties codified into law through the building code. SBCA simply believes everyone should be able to use the same standard factors of OSB equivalency in a more transparent way.
For more in-depth knowledge on this topic, please review this collection of published articles. APA has never disputed SBCRI testing or analysis by providing “Like-Kind” OSB testing even though SBCA's legal counsel, Kent Pagel, suggested they do so in a November 25, 2013 letter.
