ADVERTISEMENT

ADVERTISEMENT

What is F7 Treated Pine? (Australian Guide)

Often, you’ll hear the term ‘F7’ used when talking about treated timber.

The name is confusing for many people, as the F rating actually refers to the strength of the timber, and not the type of treatment it has received to protect against termites or rot.

So what does “F7 treated pine” actually mean?

What is an F grade on timber?

F7 is a structural rating for timber. It means the timber has been approved for use in certain structural building applications.

As covered in this guide by QTimber, structural timber is “generally sold as a (stress) graded product. A stress grade is the classification of a timber when used in structural applications.”

It states that ‘F’ grades are a “stress grade traditionally allocated to a timber based on its strength group and a visual or machine stress grading system. Higher F grade numbers are given to higher strength groups.”

Note that the required F grade should be specified by the architect or designer for the project.

The guide also explains that there are two different ways these stress grades can be derived: “either visual- or machine-grading, which specify the stress limits that apply to timbers used for structural applications.”

Finally, on this page QTimber states that F7 is a “stress grade classification of softwood timber for structural purposes. F7 applies only to softwoods (Pinus, Picea, Larix, Araucaria and Abies species).”

What is F7 treated pine?

Timber 1 | Building & Landscaping Materials

The F7 rating only tells you that the timber is structurally graded.

Another grading system known as “H” or “Hazard” determines what level of treatment the timber has had to protect it from termites and decay.

The H-level ranges from H1 to H6.

For most treated F7 timbers, it will be one of the following:

These three are all resistant to termites but they offer different levels of protection against decay, so are suitable for different applications.

What is the difference between F5 and F7 timber?

There are two main differences between F7 and F5 timber.

  • The first is the cost of each, with F7 being more expensive than F5.
  • The second difference is that the higher grade F7 can be used in higher-stress applications.

Is F7 timber treated?

F7 timber is a structural-grade timber, but just because it has this F rating doesn’t mean it is treated.

A Hazard level classification determines what level of protection timber has against certain exposures.

These range from H1 – H6, as displayed in the table below.

Timber Hazard level table | Building & Landscaping Materials
This table showing timber hazard level and treatment types has been reproduced with permission of the NSW Environment Protection Authority.

Check for a hazard rating (e.g. H3 or H4) to see if it has been treated with preservative chemicals that protect against rot and insect attack.

Any exterior work will require treated pine — this includes posts, beams and other applications where moisture may get into the wood.

Is F7 Pine structural?

F7 timber is structural, so it’s used in structural applications like roof trusses and decking.

Strength graded structural pine is subject to both tension/compression and bending stresses – unlike non-structural framing pine which is only subject to tension/compression stresses.

F7 vs MGP10 timber

MGP10, or Machine Graded Pine 10, is an Australian strength grading standard.

MGP10 and F7 are very similar types of timber.

While MGP10 is machine graded, F7 can be either machine or visually graded.

According to Timberlink Australia, “MGP10 has a higher stiffness grade while F7 has a slightly higher strength grade”.

FAQ

Can F7 timber go in the ground?

The hazard rating of the timber will determine whether it can be used in the ground. Timbers rated H4 and above are suitable for in-ground use.

Photo of author

Steve Kropp

Based in Melbourne, Steve's passion is vegetable gardening, and he’s been writing about it for almost 5 years. He also loves all things DIY and is always looking for a new project. When not working on his own garden projects or blogging, Steve enjoys spending time with his family, cooking meals with produce harvested from his garden, and coaching his son’s footy team.

ADVERTISEMENT

Leave a Comment