Understanding How Oak Beams are Graded
There are a few different grades of European Oak Beams, ranging from the highest visual grade of QPA with few knots and tight rules, right down to sleeper grade which is at the other end of the spectrum completely.
How do we decide which beams belong to which grade though?
Even at the log stage, when a tree has been felled, our experts can generally tell what grade of beams the tree is likely to yield.
There are some very definite, industry standardised rules in place for determining which grade timber in beam form belongs to. If you’re interested to learn, here is an overview of those rules.
QPA – Grade Rule Examples (The highest grade of Oak Beam we offer. Suitable for Construction.)
- In Beams longer than 3m wane is acceptable across 25% of the length of the beam as long as it is no more than 10% of the face width
- Sound sapwood is permitted on two sides as long as the total width is less than 15% of the face width
- Unsound knots are not permitted
- Frost crack is Not Permitted
QP1 – Grade Rule Examples (The second highest grade we offer, also suitable for construction).
- Wane is acceptable across 30% of the length of the beam as long as it is no more than 10% of the face width
- Two dead knots are permitted per lin metre if less than a quarter of the face width
- Unsound Sapwood is not permitted
- Rot is not permitted
Sleepers – Grade Rule Examples (The lowest oak grade we offer. Not suitable for construction)
- Wane and Bark permitted across more than one side on over 30% of the length
- Sapwood is permitted on more than two sides
- Frost Crack is permitted
- Ring Shake is permitted
- A certain amount of rot is also permitted
The above are just examples of some of the grading rules. You can find more information on the QPA and QP1 grading rules on our beam grading page and more information on sleepers here.
It is important to remember that sleepers are particularly free from restrictions on grade as mills on the continent can set their own standard for what they deem acceptable as sleepers. So, when choosing beams it is important to remember that what would be classed as defect in higher graded beams are, more than likely, allowed within sleepers.
So, sleepers are to be used decoratively as retaining walls in gardens or the edge of a flower bed for example. For constructional use higher quality beams such as QPA or QP1.