Knots, checks, shakes, and pitch pockets can lead to structural failures
Certain defects can be found in lumber depending on the grade and method of cutting: plain sawn, quarter sawn, and rift sawn. These flaws can lead to roof frame failures.
Four types of wood defects can lead to structural failures: knots, checks (cracks brought on by shrinkage), shakes (cracks that form along growth rings from bacteriological growth), and pitch pockets (cavities caused by insects or tree impacts). These can occur under normal loading. Inspection of the failed framing will help determine the role of defects in the cause of the loss.