What is at risk when we fail to use the correct lumber? If you are not careful, it could cost you your business. [For all images, See PDF or View in Full Issue.]
Several years ago, I received a call from a client searching for a solution to a problem. Unfortunately, their purchasing department got a “great deal” on some lumber, but in the process, there was considerable misunderstanding as to how this would impact their final product. First of all, Section 3.4.1 in ANSI/TPI 1–2014 states, “Truss lumber shall be the size, species and grade specified on the truss design drawing.” If substitutions are made, lumber must be substituted per Section 3.4.2.
This requirement means the substituted lumber must meet or exceed 8 specific values.
As a great reference, Timber Products Inspection has compiled design value comparison tables for several popular species and species groups. This is a helpful tool for truss manufacturers to determine if a lumber grade and/or lumber species substitution satisfies the original truss design. These charts are included in the April 2023 article by David Conner, “Truss Design Value Comparison Tables.”
One example of non-conformance would be using non-graded lumber. The lumber in the first photo has a “stamp,” but this is not a lumber grade stamp. It simply states that this lumber has been heat-treated. The stamp lacks a grade with species/species grouping.
Unfortunately, these alternative lumbers are being used in the manufacture of components – even though they shouldn’t be. In this case, the truss manufacturer has used this non-graded lumber in the floor webs.
Importantly, the lumber does not have a grade value. Even so, the fabricator is using the lumber where graded lumber is required.
Notice that the lumber in the second photo is called #4. The problem here is that there are no published values for #4. There is really no such thing as #4 – it’s just a name the lumber industry uses to say: “Does not meet #3 grading rules and requirements.”
In the situation of my client with the “deal” on lumber, the product they received was stamped as grade “Stand.” Note in the table that the value of “Stand” has Fb at 950 psi, which is less than the design requirement on a truss drawing for #2 where the Fb requirement is 1250 psi. In their situation, the substitution impacted over 120 units in a large collection of townhomes, half of which were already sheathed and some of which had C/O’s and were occupied.
The next photo is of several units of lumber purchased to be used as webbing in roof and floor trusses. It indicates the lumber is “Spec,” which according to the manufacture means “There is no grade.” In this case, there can be no comparison of values because none exist.
In a recent plant inspection for another client, it was discovered that they were substituting “Utility” for #3 southern pine. As the next chart shows, the difference in values is completely unacceptable. For southern pine, the value of Fb for utility is only 225 psi, significantly lower than the 650 psi of #3. Likewise, Ft is only 125 instead of 400. This egregious substitution has potentially occurred on hundreds of projects and will have to be resolved, impacting millions of dollars.
The requirements are clear in ANSI/TPI 1. Lumber must be graded. Substitutions must be of an equal or higher value – not just on fiber bending but all 8 values: Bending (Fb), Tension (Ft), Compression parallel to grain (Fc), Compression perpendicular to grain (Fc⊥), Shear (Fv), Specific Gravity (G), Modulus of Elasticity (E), and Modulus of Elasticity for stability calculations (Emin).
Know and Track Your Grades
After purchasing lumber, it’s also important to keep track of lumber grades at your plant, especially if you have pieces without specific stamps. How do you legitimately have pieces without grade stamps on them? First, after a truss manufacturer has received lumber into their inventory with a stamp on each piece, the standard allows the truss fabricator to crosscut this lumber. Second, it is not uncommon for a truss manufacturer to receive lumber shorter than 8’ from a supplying mill without a grade mark. This can be for assorted reasons but is often due to the automatic stamping process mills currently use. The pieces drop out of the conveyors due to their short length. The material still must be graded, but because the materials are often handled by hand, the units are segregated and labeled as a unit. The mill selling the shorts must provide qualification that this lumber meets the requirements of ANSI/TPI 1 Section 3.4.3. This certification must be issued by a lumber inspection agency accredited by the Board of Review of the American Lumber Standard Committee (ALSC). In all of these cases, it’s important that your plant has a reliable system for keeping track of this lumber by grade.
How to Remain in Compliance
- Non-graded materials cannot be used in structural components.
- Purchasing must be made aware of design requirements.
- Receiving procedures must be established and followed when receiving materials.
- Graded lumber can be crosscut by the truss fabricator without impacting the grade once the grade has been verified. This does not apply to a lumber manufacturer. (For more on this, see “When I Cut My Lumber, Do I Affect the Lumber Grade?”)
- Ripping lumber changes the lumber grade and would require a regrading step.
- The grade must be transferred by mark or segregation within the component facility.
- Non-marked but graded material must be handled by segregation or by the CM’s mark.
- Introduction of non-graded material will require the facility to track all materials to stipulate “Graded” and “Non-Graded.”
- There is no such thing as #4 lumber grade.
- Most often, the reason lumber is marked as #4 is because it does not meet #3 requirements.
- Grading lumber requires a certified lumber grader under an ALSC program.
- There is a significant liability involved if receiving anything less than #3 grade lumber into your truss facility.
The Bottom Line
Correcting mis-utilized lumber can result in replacement of components and re-evaluation of truss designs. Serious issues like lumber non-conformance can result in loss of reputation and thereby loss of customers. Obviously, this can result in millions and millions of dollars in lost revenue.
Most importantly, you can maintain the quality of your finished products when you remain in control of your raw materials. Don’t create a problem by introducing substandard material into your facility. Track lumber grades and your cutting process to ensure lumber is used appropriately. Pay attention when receiving lumber. Your customers will expect the best from you.
An ANSI/TPI 1 3rd Party Quality Assurance Authorized Agent covering the Southeastern United States, Glenn Traylor is an independent consultant with almost four decades of experience in the structural building components industry. Glenn serves as a trainer-evaluator-auditor covering sales, design, PM, QA, customer service, and production elements of the truss industry. He also provides project management specifically pertaining to structural building components, including on-site inspections and ANSI/TPI 1 compliance assessments. Glenn provides new plant and retrofit designs, equipment evaluations, ROI, capacity analysis, and CPM analysis.