This video was created by Billy from Newton Makes. It offers a practical breakdown of how to read and understand lumber stamps so woodworkers can make better purchasing decisions and avoid wasting money on the wrong materials.
Billy explains how lumber stamps provide more than just identification—they contain essential information about grade, treatment, moisture content, and origin. Understanding these codes can help woodworkers choose the right lumber for their projects and avoid costly mistakes.
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What Lumber Stamps Really Tell You
Lumber stamps are required markings that communicate important details about the board’s characteristics. Each stamp includes data about where the lumber came from, how it was processed, and what it’s best suited for.
Recognizing these codes allows you to match lumber to your project’s needs—whether structural, aesthetic, or weather-related. Billy breaks down each component so even beginners can follow along.
Grading Agencies and Standards
Lumber quality is overseen by regional inspection agencies that help enforce standardized grading systems. One of the most common examples is the Southern Pine Inspection Bureau (SPIB), which monitors lumber across the southeastern U.S.
These agencies all follow the American Softwood Lumber Standard, a framework developed by the U.S. Department of Commerce. This standard ensures consistency in grading so a 2×4 from one store is equivalent to a 2×4 from another—even if sourced from different mills.
Lumber Grades Explained
Each board is graded for both strength and appearance. Common grading levels include Select Structural, No. 1, No. 2, and Utility. The higher the grade, the fewer defects like knots, splits, or wane you’ll see.
Billy points out that even among boards of the same dimension, price and quality can vary greatly based on these grades. A board labeled “Prime” might look better cosmetically but could have a lower structural rating than a less attractive piece.
Moisture Content Markings
Many stamps include moisture indicators, such as “KD19,” meaning kiln-dried to 19% moisture content. Drier boards are more stable and less likely to warp after installation—but they’re also more expensive because of the additional processing.
Billy recommends paying attention to these markings, especially for interior projects or fine furniture builds. Boards with inconsistent moisture can shrink or twist as they dry, leading to poor results.
Heat Treatment and Export Readiness
Heat treatment is used to kill pests and is a requirement for lumber being exported internationally. Stamps that show “HT” confirm the board has been heat-treated to meet these guidelines.
Even if you’re not exporting wood, it’s helpful to know whether the board has undergone this process. It can provide added confidence that the material is free of infestations or contamination.
Tracking the Sawmill Source
Every lumber stamp includes a number that identifies the sawmill where it was produced. This traceability feature allows buyers to look up the mill and even research its practices or reputation.
Knowing where your lumber comes from helps add a layer of transparency to your purchases. Billy encourages woodworkers to pay attention to this detail, especially when sourcing large quantities.
Recognizing Lumber Stamp Variations
Lumber stamps differ based on region, species, and processing. For example, Southern yellow pine might carry different labeling conventions compared to fir or spruce.
Learning to identify these patterns helps ensure you don’t mistake one species for another, especially when shopping in bulk or mixing wood types in a project. Billy highlights common differences in stamp appearance across the U.S. and Canada.
SPF vs. SPFs — What’s the Difference?
A common question is what the “s” means in lumber labeled SPFs. SPF stands for spruce-pine-fir, a common softwood blend. The “s” indicates that the lumber comes from southern mills, while SPF without the “s” usually means the wood was sourced from Canadian producers.
Understanding this distinction can affect cost, strength, and performance, especially if you’re matching boards from different batches.
Canadian Lumber and the NLGA
Canadian lumber follows similar guidelines, though governed by agencies like the National Lumber Grades Authority (NLGA). Their stamps use unique coding but still conform to international standards.
Billy explains how Canadian stamps often include grading details in both English and French and might feature certification from the Canadian Lumber Standards Accreditation Board (CLSAB).
Other Markings: Edge Radius and More
Some boards may also include markings about edge treatment, such as a rounded edge radius. This is especially important for trim or furniture projects where sharp lines are part of the aesthetic.
Knowing what these marks mean can save you from buying boards with finishes or profiles you don’t want. Billy suggests always checking for these smaller stamp details before heading to checkout.
Conclusion
Understanding lumber stamps is a must for any serious woodworker. These markings may seem like technical codes at first, but they offer real insight into the board’s quality, purpose, and value.
Billy from Newton Makes does a great job explaining how to decode this information so you can shop smarter, spend less, and get better results in the workshop.
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