Why Should I Care about Code Compliant Braced Wall Design Values?
Originally published by: Qualtim, Inc — August 29, 2011
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The Structural Building Components Research Institute (SBCRI) provides a very thorough answer here - http://sbcri.info/bwpex.php
- A code compliant 3/8” OSB braced wall panel has a range of design values from 239 plf to 870 plf (a 364% difference) for an identical application. The only design value change is based on whether the application is in a wind or seismic zone, or in one of the following code or standards – IBC, IRC, WFCM or SDPWS – each potentially giving a different design value.
- Do different design values for the identical application, depending on the building’s location, or the specific code used, match up with what one would expect from a common sense perspective?
- Why would one use 239 plf when one can use 870 plf for an identical application much more cost effectively and competitively (i.e. less OSB used compared to any competing product)?
- Clearly 3/8” OSB braced wall panels with interior gypsum in a residential application have a code mandated competitive advantage given that the code allows an 870 plf nominal unit shear capacity value, when the tested nominal unit shear capacity resistance is actually around 436 plf.
- How does a new product that has equivalent performance compete when it would have to be 2 times better to simply be equivalent?
We have previously sent this information out to the following people:
- Mr. Jimmy Brothers, ICC President
- Mr. Mike Pfeiffer, ICC AHC-WB Staff
- Mr. Michael Beaton, P.E., Senior Vice President of ICC-ES
- Mr. Henry Green, National Institute of Building Sciences (NIBS)
- Mr. Brad Douglas, P.E., American Wood Council (Developer of SDPWS, WCFM and NDS)
We have done our very best to make this information easy to read, and we have created a series of web-based pages that provide all the information in a “library-like format” for easy downstream use. In addition, we have provided all the data that supports our work so anyone can assess its accuracy.
Certainly, if there is anything we have provided that is technically incorrect, we will take steps to correct it. There is no pride of authorship in any of this work; we merely desire a deep technical understanding so we can make the best possible future engineering decisions.
We have one goal only: advance building construction through technically responsible and accurate engineering innovation (which is extremely hard to do when the code builds into it at least a 200% competitive advantage for one product line like it has for WSPs). All anyone can ask for is a level playing field upon which to compete.
Further it is our intent to help the structural building component industry do what it does best:
- Provide valuable engineered structural building components (i.e., trusses, wall panels, I-joists, etc.) that can be used in creative and technically sound ways.
- Advance building construction through full advancement of the whole-house design software taking shape in the structural building component industry, and then through technically sound product development.
Neither of these goals is fully possible under current conditions. Likewise, there is no transparent engineering foundation defining the building code requirements in such a way that competing products can use an identical engineering pathway to truly be competitive.
All our future engineering work will be performed in the context of the current code complying engineering tables, at least until work is undertaken by the ICC, ICC-ES and/or AWC to make appropriate engineering changes they deem are needed, if any.
Our engineered design drawings will show and state that the engineering performed is in compliance with the current published tables of the IRC, WFCM, and/or SDPWS/IBC, and will show the design values that have been used as code complying equivalents, where the explicit responsibility for the design approach is with the ICC, ICC-ES and/or AWC as published in the code.
We intend to take all actions within our control to provide competitive engineering for the Structural Building Component Industry and our Qualtim/SBCRI customers. Thanks in advance for your consideration. Any feedback/assistance you are willing to provide to help us foster robust building construction innovation would be greatly appreciated.
Kirk Grundahl, P.E.
President of Qualtim, Inc.