What are the Minimum Grade Requirements for Lumber When Manufacturing Components?

With high lumber costs and volatile pricing, it is very reasonable to look for options to normal resources. Many fabricators and lumber manufacturers have been experimenting with using non-regular channels for lumber, including some choices that have created problems and issues with their finished products. These situations have resulted in a non-compliance relating to their quality assurance because they are not following Section 3.4 in ANSI/TPI 1–2014 that states, “Truss lumber shall be the size, species and grade specified on the truss design drawing.” Lumber may be substituted per Section 3.4.2, however, the substituted grade must meet 8 specific values. To determine if the substitution meets the requirements, values must be available explicitly for the substitution. [For all photos, See PDF or View in Full Issue.]

One example of non-conformance is the use of non-graded lumber. The lumber in the 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.

The next photo is of several units of lumber purchased to be used as webbing in roof and floors. It indicates the lumber is “SPEC,” which according to the manufacture means “There is no grade.”

Then we have photos showing lumber marked as #4 Southern Pine. The problem is that there are no published values for #4. There is really no such thing as #4. It’s a name the lumber industry uses to say: “Does not meet #3 grading rules and requirements.”

Unfortunately, these alternative lumbers are being used in the manufacture of components – even though they shouldn’t be. Here is a photo of a manufactured truss using non-graded lumber in the floor webs.

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 (F_b), Tension (F_t), Compression parallel to grain (F_c), Compression perpendicular to grain (F_c⊥), Shear (F_v), Specific Gravity (G), Modulus of Elasticity (E), and Modulus of Elasticity for stability calculations (E_min).

Now, with that being said, how do we keep track of lumber grades? Once 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. Also, it is not uncommon for a truss manufacture to receive lumber (shorter than 8’) from a supplying mill without a grade mark. This can be for various 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 since 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 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).

How to Remain in Compliance

1. Non-graded materials cannot be used in structural components.
2. Receiving procedures must be established and followed when receiving materials.
3. Graded umber can be crosscut by the truss fabricator without impacting the grade once he verifies the grade. This does not apply to a lumber manufacturer. (See also my April 2017 article, When I Cut My Lumber, Do I Affect the Lumber Grade?)
4. Ripping lumber changes the lumber grade and would require a regrading step.
5. The grade must be transferred by mark or segregation within the component facility.
6. Non-marked but graded material must be handled by segregation or by the CM’s mark.
7. Introduction of non-graded material will require the facility to track all materials to stipulate “Graded” and “Non-Graded.”
8. There is no such thing as #4 lumber grade.
9. Most often, the reason lumber is marked as #4 is because it does not meet # 3 requirements.
10. Grading lumber requires a certified lumber grader under an ALSC program.
11. There a significant liability involved if receiving anything less than #3 grade lumber into your truss facility.

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 the 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.