Reading the chart
This chart, created by the National Hardwood Lumber Association (NHLA), records the minimum requirements a board must meet to merit a particular grade. Generally, a higher-grade board is longer, wider and more defect-free than one of a lesser grade. The clear pieces are obtained with as few cuts as possible.
By comparing the dimensions of a board with the figures supplied in the chart, it is possible to determine the grade of a particular piece of lumber. The first two horizontal rows pro
vide data on minimum board dimensions for each grade. The third row gives information on the percentage of defect-free surface, or clear face cuttings, a board must have for each grade. The minimum size of each clear face cutting is listed in row four. Once the surface area, or surface measure (SM), of a board is determined, the formula in row 5 will give the total number of cuttings allowed for a particular grade. Row 6 contains the number of clear cuttings each grade permits.
The location of lumber grades on a log
High grades of lumber, such as FAS and Select, are generally cut from the outer part of the log, near the bark. No. 3 Common grades, found closer to the pith, are not always suitable for cabinetmaking and are frequently used for packing crates or pallets.
In some species, such as walnut, where color is important, the sapwood does not qualify as top grade, even though it may be clear.
