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 | Unseasoned | Strength GradingSeasoned | Strength Grading
---|---|---|
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 |