Transparent Understanding of the Rules Clarifies the Path to Innovative & Value-added Engineering

It has become clear to me, through attendance at the American Lumber Standards Committee (ALSC) meetings, the Southern Forest Products Association (SFPA) meetings and several individual and group discussions, that there may be some misunderstanding of my intentions when I tenaciously ask for clarifications of the “rules for the development of the raw material design values” and the “rules with respect to professional engineers transacting proprietary engineering as a value-added business.”

The structural building component (SBC) industry is a significant “engineered solutions providing” business. The only true way to create new value inside this engineering business is to differentiate based on engineering and component manufacturing acumen. Engineering differentiation means undertaking innovative and creative engineering through sound science (testing and calibrating math to testing) and wisdom-based art (using knowledge and experience to make engineering judgments that are unique in some manner).

Design Value Precision Is a Value Proposition

As I have consistently said everywhere I have spoken on this topic, everyone buying raw materials for structural components or conventional framing applications is purchasing design values and related properties for use in engineering equations to resist loads for a given load path. In order to undertake this work to create greater value through an engineered structural building component solution, it is important to understand how raw material design properties are derived.

There is a typical engineering community and market expectation that the National Design Specification^® (NDS^®) for Wood Construction equations provide precise resistance to applied loads, as long as the numbers generated by the NDS equations “work” (i.e., the math says that the resistance to load is greater than the applied load).

It is not well known that lumber design values are global in nature and not specific to the piece of lumber being used. Some lumber mills are selling 16,000 psi bending strength lumber at a 2,300 psi bending strength value because design values are based on this global design value creation model. In other words, the global visual grading process yields lumber with a wide range of strength properties. A given mill may have trees that generate a high percentage of 16,000 psi lumber, yet the visual strength value for this 16,000 psi lumber is assigned 2,300 psi. Therefore, in simple terms, 16,000 psi = 2,000 psi.

Clearly, this example has a value opportunity cost and loss of 14,000 psi. This economic value loss is due to the way the visual grading procedures have been established by PS 20 and the commodity sales concepts used to sell lumber. A key issue is, given commodity lumber selling, we do not know what the true opportunity cost is.

This would seem to provide an obvious value addition opportunity for the use of an alternative set of lumber design value groupings (i.e., refined visual or MSR grade sorts) or more creative lumber design value creation methods.

This same type of design value variability also exists for OSB and plywood. Again, there is value creation opportunity for manufacturers who have a detailed understanding of wood structural panel performance strengths and weaknesses for their specific product lines and market segments. The same concepts apply to steel studs, truss plates, steel webs and chords, I-joists, LVL, glulam, fasteners, hangers and any newly developed products. A detailed knowledge of design value strengths, weaknesses, precision, knowledge of boundary conditions and key engineering judgments that can and need to be made will create engineering value-addition opportunities. The best way to define strengths and weaknesses is through benchmarking or comparative performance testing.

Much of the imprecision and lack of understanding of the judgments that have gone into design values goes away when one has test data. Testing unmasks actual performance characteristics and provides great insight into comparative performance and the path to adding engineering value. Great learning is always done through testing.

An increase in engineering sophistication will bring about more economical and innovative structural component use and building designs. This will provide even greater value creation opportunities for raw material manufacturers and software providers who choose to invest in and take advantage of testing, calibration and the hard work that goes hand in hand with this.

The Code, Professional Engineering & Code Compliance

The building code is the law. Design values written into the building code then become the law, whether they are scientifically correct or not. As I have said repeatedly, the code development process today is more of a political process than a purely technical consensus process. 

It has been clear to me for quite some time that the International Residential Code (IRC) has defined a typical IRC-compliant isolated OSB braced wall panel without interior ½ regular gypsum wallboard applied as having a lateral resistance design value of 600 plf, and the same wall panel with interior ½ regular gypsum wallboard as having a lateral resistance design value of 840 plf (see pdf attached below for the SBCA IRC code change proposal that transparently defines these design values). Simpson, APA and Washington State University testing through Professor Dan Dolan, as reported to the Building Seismic Safety Committee (BSSC) in a 2007 APA report, suggests that the real lateral resistance design value for these wall configurations could be 351 plf and 383 plf respectively.

In contrast to the lumber example above where 16,000 psi = 2,300 psi, in the case of OSB, the code legalizes a competitive advantage per the APA reported test values for OSB of 351 plf = 600 plf and 383 plf = 840 plf. For those who do not know the details of the development of the IRC braced wall panel design values, a detailed review of the background minutes and test data will lead you to conclude that the development of this section of the code was based on judgments of a small group, not pure fact-based testing or sound scientific methods. While using engineering judgment is generally fine, it is important when doing so to be conservative and think about unintended downstream consequences of the judgments being made. This is hard to do, so if that is not possible when new data is brought forward, it seems prudent to advocate for any corrections needed so a natural competitive landscape is not artificially altered.

A similar set of facts exist with respect to the development of wood structural panel seismic design coefficients within ASCE 7 Chapter 12 Table 12.2-2. More on this in a 2014 article, as this is just the tip of the iceberg.

It is challenging for the engineered design of wall panels to compete with legally defined conventional framing design values that lead to a competitive advantage of nearly a factor of two, unless one has detailed test data about OSB performance and can use that data to make engineering judgments. There are a wide variety of reasons for this inequity that will be detailed in future articles, taking one issue at a time, because the details can get overwhelming rapidly.

Another fact that is often misrepresented is, if the law is treated forthrightly as written, professional engineers have great value in the market because they can assess test data (like that in the lumber and OSB examples already listed), do comparative analysis and make engineering value judgments based on their unique expertise. To make the best value judgments, innovative engineers will define the benchmarks, undertake scientific method comparisons, make good engineering judgments, and provide reasonable and competitive design values for new products through the knowledge of all facts related to testing and design value development.

The building code defines an “approved source” as follows:

A professional engineer is defined in professional engineering law as:

Therefore, based on these definitions, it is logical that a Professional Engineer would be considered an Approved Source.

Further, the building code often says that implementation of the code is to be in accordance with generally accepted engineering practice in a manner similar to the intent of the following code provision:

Generally, this is accomplished through the following code-based concepts through approved sources:

All of this is the rule of law, so professional engineers ought to be passionate about innovative ideas that form the link between scientific discoveries and their subsequent application to human needs and quality of life. Therefore, one of a professional engineer’s opportunities is to assess and take responsibility for that assessment by standing behind it through the application of their engineering seal.

This process can also differentiate innovative engineers from status quo engineers. Value differentiation by engineering companies and their engineers is an important strategic engineering business decision. The law embraces this concept and provides a straightforward pathway for engineering ingenuity, intellectual property development, proprietary applications and value addition.

Conclusion

This article is intended to set the stage for a series of articles focused on defining rules that many may not be aware of. However, when one spends some time looking at them, it is possible to develop a different understanding than what some in the market would have you believe. The concepts that will be considered in this context include codified design values and “approval” decisions that create arbitrary winners and losers, as well as state laws and state actions, which may not always be the same..

Change is difficult, but only inside advocacy for change do most believe that true value creation opportunities exist.