Structural Grades

Timber grading systems have been developed to ensure quality control in the industry and help consumers buy the right timber products for their needs.
The Log Resource

Prior to being cut, each log is scanned and assessed for defects and the optimum cutting pattern.
Higher structural grades are typically produced from the outer areas of the log, while industrial and lower structural grades are often cut from the areas closer to the centre of the log.

Hyne Timber - Log Structural Grades

Machine Stress Grading

Machine stress-grading uses a machine to bend each piece of timber (generally about its minor axis).

The machine measures the stiffness of the board and uses a correlation between stiffness and strength to assign a stress grade. A sorted group with a small range of E (stiffness) can produce a larger range of strength. The E value is also used to infer all of the other structural properties, including tension, compression and shear strength.

Machine stress-grading leads to the classification of timber on the basis of structural properties, and the different groups are directly given either F-grades or In-grade structural properties, which are appropriate for the whole parcel of graded timber. Machine stress-grading is often perceived as more objective and efficient than visual grading methods.

MGP Grades
Grade Description Applications
F5 Base grade for structural applications Wall frames, roof trusses
MGP10 Most commonly used structural grade Wall frames, roof trusses, beams, rafters
MGP12 High load applications Wall frames, roof trusses, beams, rafters
MGP15 High load applications and engineered products Wall frames, roof trusses, glue laminated beams

 

Data Collection

Every piece of timber framing is machine stressed and awarded a structural grade. At Hyne Timber, this data is recorded and kept on file for at least 12 months - resulting in approximately 2gb of data per pack of timber framing.

Structural properties are defined in AS1720.1 for the nominated grade. The product requirements are defined in AS/NZS1748.1.