The 5 Percents of Lumber
Feature
The 5 Percents of Lumber
- Wood, like other structural materials, exhibits an inherent variability in strength properties from piece to piece.
- The design value is obtained by reducing the fifth percentile test result by a property reduction factor.
- The grading of lumber is not an exact science; a reasonable amount of discrepancy is to be expected between individual pieces graded by different graders.
- Cross-cutting stress-graded lumber into pieces shorter than the original piece is a common practice wherever lumber is used in construction.
2007 December