In our previous BLOG, Shakes Checks and Splits in Dimension Lumber, we discussed the differences between these three types of defects or characteristics found in dimension lumber. All three are commonly thought of as different types of “cracks” or, “splits” in the wood. Each will have different limits in various grades depending on their effect on the strength and/or appearance for a particular stress rated or non-stress rated grades. There remains, however, some confusion between shakes and splits. After all, both shakes and splits create a longitudinal separation, or a “split”, in the wood, so what is the difference?
Grading Knots Away From the Edge
Learning to grade edge knots and combination knots in dimension lumber takes a fair amount of study and practice. These type knots most often limit the grade of a piece. Once the grader has a complete understanding of how these knots are measured and limited it becomes a matter of closely judging the size of what you see and comparing this to a known limit for a known knot size. This makes it relatively easy to estimate the size, and grade accurately on edge and combination knots.
If you are learning to grade Dimension Lumber for the first time, there are some basic facts and skills that you should study and practice before working with your trainer. Following is a list of these along with some tips, and further clarifications of rules that have proven vital to mastering the art of lumber grading. Studying, practicing, and memorization of these will speed up your training process.
Often end users of Dimension Lumber complain that lumber from different suppliers does not appear to be of the same quality. It may look better or worse, yet the packages bear the same grade mark. The lumber could be graded correctly; however there are indeed some factors that can influence the overall appearance of lumber in a specific grade, – for better, or for worse. Remember the grading rules for Dimension Lumber were written primarily to control the strength of pieces within a grade, with only a limited consideration for appearance.
What is Warp?
Warp is defined as any deviation from a true or plane surface, including bow, crook, cup, twist, or any combination thereof. Warp restrictions are based on the average form of warp as it occurs normally, and any variation from this average form, such as short kinks, shall be appraised according to its equivalent effect. Continue reading “Warp in Dimension Lumber”
The Southern Pine Inspection Bureau is pleased to announce two new varieties of the SPIB eLearning courses for Dimension Lumber. These West Coast and Canadian courses now include lessons, rules reviews, and knot tests for the Light Framing Grades of Construction, Standard, and Utility; as well as Select Structural, and Studs. These lessons are available to add to the basic courses which cover No. 1, No. 2, and No. 3.
Keeping a competitive edge means training and retraining your lumber graders. You may want to consider a little different approach when new methods or equipment like grade scanners are introduced that requires new skills and/or when employees that were previously trained in a different situation are lost.
What is the difference between a shake, a check and a split?
They are similar in that they all are separations lengthwise in the grain of the wood; however, each has a different origin and a different effect on the grade of dimension lumber. First, let’s look at the definition of each.
What is Dimension Lumber?
We have all seen buildings being framed with lumber. Do you know what type and grades of lumber are used in this framing process? Sometimes referred to as “dimensional lumber” or “framing lumber”, this wood is the mainstay of the housing industry in the US and Canada. Dimension lumber, as this lumber is formally labeled, is defined as lumber of nominal thicknesses of 2 inches TO LESS THAN FIVE inches and nominal widths of 2 inches and wider. It is smoothly surfaced softwood lumber that is sold and marketed by the “nominal sizes”, rather than the real final standard surfaced sizes, which are actually somewhat smaller than nominal sizes. In other words, lumber’s nominal dimensions are larger than the actual standard dimensions of finished lumber.