Lumber Grade Stamps

A grade stamp is printed on lumber produced in North America, but what does it mean?
Since lumber comes from a natural source, much of it has naturally occurring defects, such as large knots or splits, and these can reduce its strength. Because of these and less obvious defects, lumber that leaves a sawmill must be appraised by trained inspectors and assigned a grading stamp. (read full article on InterNACHI)