Clients often ask the difference between Green Oak and Seasoned Oak and which is better. Both Green Oak and Seasoned Oak are from the same Oak tree (it is not a different species) the only difference is the level of moisture held in the specific piece of timber which is determined by how long the tree has been felled and the circumstances it has been subjected to.
What is Green Oak?
Green Oak refers to how fresh the Oak is and can also be known as Fresh Sawn Oak. This is Oak that has been cut within 3 to 18 months after the tree has been felled, and therefore it has a high moisture content, usually 60-80%, and will still be drying naturally.
Green Oak is much easier to work with; its high moisture content makes the timber more suitable for cutting and shaping the joints precisely. However, this also makes the timber more susceptible to moisture movement as the beams shrink as they continue to dry. This movement is taken into consideration when manufacturing the building, to ensure the tightening of the joints will improve the overall strength of the frame, instead of the structure moving out of place.
Due to the readiness of this stage of Oak, it is the most cost effective.
What is Seasoned Oak?
Seasoned Oak, also known as Air Dried Oak, is Oak that is cut to size and stored outside to dry naturally which reduces its moisture content to around 20-30%. This can typically take several years depending on the thickness of the Oak. This drying process can be accelerated by using a kiln – this is then referred to as Kiln Dried Oak.
During the drying process of Seasoned Oak, the beams settle and dry from the outside inwards which can cause them to bend and split naturally. By allowing the Oak to dry before it is used, the movement after installation is reduced to a minimum. This means that beams are much more likely to remain straight once in place, although characterful splits and shakes will still appear, they will be less significant.
As the Oak dries the structure gains strength as it swells and settles into place around fixings, permanently fusing the joints together.
Due to the years of drying required, this timber carries a greater cost than Green Oak.
Kiln Dried Oak is even higher in price due to the cost of the process involved in reducing its moisture level to its lowest.
When to use each type of Oak?
Due to its low moisture content, Seasoned Oak has little movement which makes it the ideal choice for projects containing glazing. Using Seasoned Oak for Orangeries, Garden Rooms and Conservatories ensures minimal movement in the timber, prevents glazing from shattering and creating gaps between the joints which can cause draughts as a result of the timber ‘drying out’ and moving in situ.
Therefore, here at Prime Oak, we only use Seasoned Oak for our glazed extensions due to the minimal movement and will use Green Oak for buildings that include little to no glass/glazing such as Garages, Stables and Annexes. All of our joinery (Doors and Windows) are made with Kiln Dried Oak to ensure no movement is expected that could result in stress on the glass panes.
As our focus lies heavily on providing the best quality product, we always ensure that along with using the correct type of Oak for each project, we also use the correct cut of Oak for each beam that is used, depending on where it is to be used on the project.
We pride ourselves in never cutting corners, regardless of our costs for top quality cuts of Oak, we will never compromise on the quality we deliver.