FNR—103

forestry & natural resources
MARKETING AND UTILIZATION
Lumber Grade Yields for Hardwood Sawlogs
by Daniel L. Cassens
Forest Products Marketing and Utilization Specialist
Log grades are a measure of log quality and thus an indication of value. Nearly all hardwood sawmills in the Central States Region use some sort of a grading system when purchasing sawlogs. This grading system should serve at least three purposes. First, the system should enable a mill to relate the quality of the raw material input to the value of lumber output. Any drop in the output-input ratio should alert management to potential problems. Second, if expected yields from available logs are known well ahead of time, markets for this lumber can be searched out. Third, the grading system and accompanying log pricing structure should encourage woods workers to obtain the best possible sawlog yield for each tree stem, thus helping extend a valuable and limited resource.
Since the value of a sawlog ultimately depends upon the volumes of each lumber grade produced, a strong correlation must exist between log and lumber grades. The U.S. Forest Service Log Grading System can predict the yield of lumber by grade from different sizes and qualities of logs. In addition, this log grading system correlates closely with the National Hardwood Lumber Association (NHLA) grading rules for hardwood lumber in that the percent of log length required in clear cuttings for No. 1, 2, and 3 logs is the same as the percentage of clear cutting area required for FAS, No. 1 common and No. 2 common lumber, respectively. The minimum clear cutting length for No. 1, 2, and 3 logs is the same as that for FAS, No. 1 common and No. 2 common lumber, respectively. For additional information on the relationship between the Forest Service log grades and the NHLA lumber grades, consult the list of additional readings at the end of this publication.
This publication will present the lumber grade yields by Forest Service log grade, diameter, and species. The log grades rank logs suitable for the manufacture of factory grade lumber into categories of high (Log Grade 1), medium (Log Grade 2), and low (Log Grade 3). The lumber yields are based on U.S. Forest Service studies of approximately 11,000 logs sawed at 28 sawmills in the Northern, Central, and Southern Hardwood Regions. During the study each log was diagramed, providing as accurate a record as possible of the exterior and ends of the log. Logs were then sawed and the yield per log, in board feet of green lumber, was tallied by board grade and thickness. No allowance was made for degrade that might occur during seasoning. Lumber yield data for grades 3A, 3B, SW, Timbers, Ties, and sound square edges are combined into one group (3 A+B) for this report.
The species for which data are available and the respective table numbers are as follows:
Table 1. Basswood Table 2. Beech Table 3. Cottonwood Table 4. Hard Maple Table 5. Black Oak Table 6. Red Oak (upland)
Table 7. White Oak (upland)
Table 8. Yellow Poplar Table 9. Sweetgum
In addition to these species, additional data are provided as follows:
Table 10. Ash Table 11. Hickory Table 12. Soft Maple Table 13. Sycamore
PURDUE UNIVERSITY • COOPERATIVE EXTENSION SERVICE • WEST LAFAYETTE, INDIANA 47907