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Choosing between Green and Air Dried Oak Beams
Our constructional Oak beams ae provided in three different grades:
- QPA
- QP1
- Air Dried Constructional
QPA and QP1 are both Green/fresh sawn whereas the air dried constructional has been left drying for 3-5 years. So how do you choose between them?
Usually your structural engineer would specify what type of oak beams to use but there are key differences which you might like to know about.
- Appearance
Green Oak beams are a light brown and haven’t been drying for long periods of time, they are provided straight from the log so there are less splits and cracks and even just the sawn beams won’t be a dark silvery grey colour.
QPA is the cleanest grade of the two available and you can see the beam grading rules in our timber knowledge library.
On the other-hand air dried beams have been left to dry for 3-5 years and the surface splits, cracks and shakes in the wood have already developed. The timber will also be a dark silver grey in colour (unless planed or sawn down from a standard size).
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Green Oak
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Air Dried
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- Structural Grading
The highest graded timber is QPA, a visual grade which is equivalent to the D30 strength grade and QP1 which is equivalent to D24.
When originally cut from the log, our Air dried beams are graded to QP1, however, once they have been left to dry they can no longer be graded as that because of how much the timber changes.
If I Use Green Oak beams will they become Air Dried?
Over time all Oak beams will dry out, shrink and weather to a dark silver grey colour if left outside. As the timber dries out it will also start to develop splits, cracks and shakes although the structural integrity of the Oak will remain.
It is completely normal for the timber to move and develop splits along the surface, there is no need to do anything to stop or rectify this, the Oak will still be OK.