Timber Strength Grading

There are various factors that determine the strength grades of timber. In Australia, the timber industry uses two grading systems for solid timber - the visual stress grading (F-grading system) for both softwoods and hardwoods and the machine stress grading (MGP-grading system) specifically for pine timber. The F-grading system measures the bending strength of a piece of timber, while the MGP-grading system measures its modulus elasticity, which takes into account stiffness, compressive strength, and shear strength. It's important to note that F-graded timber can be substituted with MGP-graded timber, but the reverse is not possible. For your convenience, we have included a table below showing the strength F-grading of the most commonly used timber species.
Timber Species UnseasonedStrengthGrading SeasonedStrengthGrading
Mountain Ash - F11 - F27
Silvertop Ash F7 - F17 F11 - F27
Blackbutt F8 - F22 F14 – F34
Western Cedar Up to F7 Up to F8
Douglas Fir (Oregon) F4 – F7 F7 – F17
Sydney Blue Gum F7 – F17 F11 – F27
Grey Gum F11 – F27 F14 – F34
Mountain Grey Gum F7 – F17 F14 – F34
Forest Red Gum F7 – F17 F8 – F22
River Red Gum F4 – F11 F7 – F17
Spotted Gum F8 – F22 F14 – F34
Grey Ironbark F11 – F27 F17 – F34
Red Ironbark F8 – F22 F11 – F27
Jarrah F5 – F14 F8 – F22
Kwila (Merbau) F8 – F22 F11 – F27
Red Mahogany F8 – F22 F11 – F27
Southern Mahogany F8 – F22 F11 – F27
White Mahogany F8 - F22 F11 – F27
Messmate F7 - F17 F11 - F27
White Cypress Pine F4 – F11 F5 – F14
Radiata Pine F4 – F11 F5 – F14
White Cypress Pine Up to F8 F5 – F14
Brown Stringybark F7 – F17 F11 – F27
White Stringybark F7 – F17 F11 – F27
Yellow Stringybark F7 – F17 F11 – F27
Tallowwood F8 – F22 F14 – F34
Turpentine F7 – F17 F11 – F27