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 |
