Timber grading is the process by which timber is sorted into groups with ideally, similar appearance or structural properties in each group. Inevitably there is a range of properties within a group and significant overlap in properties between the groups. Timber is specified by its grade, so it is important to understand the terms used in grading, and the implied properties and characteristics of each grade. The sorting of appearance products is quite different to the sorting used for structural products. The two different set of criteria are treated separately in this section. As there may be cases where the timber has both appearance characteristics and structural properties, it is important that all users of timber understand the implications of both types of grades.
Types of Timber Grading
• Appearance grading • Structural grading • Visual stress grading • Machine stress grading • Machine proof grading • In-grade testing • Stress grades • Quality control |