An oak beam is one of our favourite products. Steeped in tradition, this glorious timber has many uses in a structural sense. So, what should you expect from your oak as it ages? What are the main characteristics of this fine material?
We answer the most pressing questions.
Should oak beams crack?
In a nutshell, yes, they should. Green oak beams have a high moisture content so are subject to splitting and cracking as they dry out. This process occurs because the timber shrinks along the width and thickness.
If you aren’t used to working with fresh sawn oak, the changes it goes through can be quite alarming. However, it is important to remember that the timber remains structurally sound during these changes, and it is perfectly natural for it to change.
How long will untreated oak last outside?
Fresh sawn oak can last 30-40 years when left untreated and when not in contact with the ground, it can last even longer. When left in constant contact with the earth, Oak will decay quicker than if it is set in concrete or raised off the floor. This is why we recommend metal shoes, staddle stones, or concreting the posts into ground on our Gazebos and Pergolas.
What can I expect to see in fresh sawn oak?
The timber can vary greatly in quality between grades. For example, the difference between QP1 and sleepers is chasmic. So, what can you expect?
This is the top grade of fresh sawn oak, there will be knots in the timber with the possibility of a small amount of wane. All knots should be sound and there would be no holes, end shakes, ring shake, star shake, bark pocket, brown pith, brown streak or rot
QP1 is similar to QPA grade however a larger amount of wane is allowed within the grade along with brown streak, black holes and brown pith.
Sleeper grade is an outlier to the two construction grades above. There are no set rules for sleepers so defects like rot, unsound knots, shakes, and large amounts of wane are allowed. Oak sleepers are mainly for flower beds and despite being more durable, look a lot rougher than your standard softwood sleeper.