A stress grade tells a designer the structural properties of a piece of timber, so they can size it. MGP stands for machine graded pine; the number in MGP10, MGP12 and MGP15 refers to a rounded stiffness value. F grades such as F5 and F7 are another set of stress grades. A grade says nothing about treatment: H3 or untreated is a separate label. Use the grade your plans specify.
How machine grading works
According to WoodSolutions, machine stress-grading bends each piece, measures its stiffness, and uses that to assign a stress grade, which is then marked on the piece (WoodSolutions, machine stress-grading). The machine output can be an F grade or an MGP grade. MGP grades can only be given to Australian pine that has been machine graded, and the grade of the whole piece is shown by the printed mark along it.
What the numbers mean
- MGP10, MGP12, MGP15: in WoodSolutions' words, the "10" refers to 10,000 MPa, a rounded characteristic modulus of elasticity (stiffness); the other MGP grades follow the same convention (WoodSolutions, in-grade testing).
- F5, F7 and other F grades: a separate stress-grade system used across many timbers.
- MGP10 vs F7: WoodSolutions describes them as similar but not exactly equivalent, with span tables that differ between the two. If the grade supplied differs from the grade on your plans, ask your designer to re-check the sizes. We do not substitute one for the other without that check.
WoodSolutions' Domestic Timber Deck Design guide notes that treated softwood is predominantly available in F7, with F5 and MGP10 in some regions.
Grade is not treatment
MGP10 can be untreated or treated. Treatment (H2, H3, H4 and so on) is about protection from insects and decay in a given exposure. Your plans should give both. See H3 vs H4 treated pine for treatment.
The grades we list
| Product | Grade |
|---|---|
| 90 x 35 and 90 x 45 untreated pine | MGP10 |
| 90 x 45 and 140 x 45 treated pine | MGP10 |
| 70 x 35, 70 x 45 and 90 x 35 H3 | MGP10 / F7 as shown by our supplier |
For the sizes themselves, see choosing an H3 treated pine framing size.
FAQ
Is MGP12 stronger than MGP10?
MGP12 is a higher grade with higher design properties. Which one a member needs is your designer's call; we do not list MGP12.
Where is the grade marked?
Machine-graded pine carries a printed grade mark along the piece.
Can you supply a grade you do not list?
Send the section, grade, treatment and quantity through request a quote.
Sydney Timber Supply team
Grading references from WoodSolutions, including its Technical Design Guide 21, Domestic Timber Deck Design (revised October 2020), page 7; product grades from our product pages. Reviewed November 2026.