Oak - how to check the quality of the grade: Ensuring timber longevity outdoors

Oak is one of the nation’s favourite and most beloved timbers. It is strong and durable, with a longstanding heritage which makes it one of the most traditional choices for timber construction. That being said, not all Oak is made equal. To ensure you are choosing the right timber for your project, learn more about how Oak is graded in this guide.

What is Oak Timber Grading?

Strength grading Oak refers to the process of checking Oak beams or boards to determine their suitability for different applications. This is done because not every Oak beam is going to be identical. Structural properties can vary between different pieces, affecting durability, strength and longevity.

By grading your Oak timber, we can work out individual characteristics. This gives you far better insight into the exact boards which are going to provide the best outcome for your construction project.

Common Oak Grades

By understanding what Oak grades are and the different classifications available, you will instantly be in a better position to make the right choice for your intended application. At EcoChoice, we use a variety of different grades to sort our timber, including:

Strength Grades for Oak

We follow the BS EN 338 and EN14081 specifications when strength grading Oak to determine just how tough specific boards are. The most common strength grades for Oak timber are:

• D24: This is a pretty standard strength grade for Oak, meaning that it is suitable for most structural uses where moderate strength is a must.
• D30: This is a stronger Oak, and is typically the highest grade you can find. (D40 is technically possible but very rare and, essentially, unnecessary). You should opt for D30 Oak if you have extraordinary strength requirements.

You can also choose Oak which is not strength graded. This is common for non-structural applications, such as cladding.

Appearance Grades for Oak

Another way of grading Oak is by how it looks; its natural features, colour consistency, knots and other visual traits. This type of grading also helps to determine where the beam is best used, be it for cabinet doors and structural beams for house frames.

In the UK, Oak intended for visible joinery or beams, for instance, is graded under the European standard EN 975-1, which sets out how visual qualities should be evaluated.

Oak is commonly labelled with a three-letter code which summarises its species, product type and grade. A typical example would be QBA:

• Q – Identifies the species group. For Oak, the Latin name for the oak genus is Quercus, so the letter Q is used.
• B – Indicates the form of Oak being supplied. (B: boules, S: selected boards, F: strips, P: beams)
• A – Shows the visual quality level. A is the top tier, followed by 1, 2, 3, and 4, with 1 being good quality and 4 being the lowest acceptable grade.

You may occasionally see an X added at the end of the grade. X denotes sapwood visible on one face of the board, while XX indicates sapwood on both faces.

How to Check the Grade of Your Oak

This is a quick introduction to grading, but it can get a little more complex. If you are struggling to check the quality of your Oak grade, do not panic; we are here to help. As timber experts, our team at EcoChoice will be happy to chat more about Oak grading and your project requirements, ensuring you end up with the exact boards of Oak which you need.

Get in touch to learn more.