Timber is Kiln Dried to dry the boards without it weathering and checking like wood that’s air dried. This means that the timber shrinks considerably as the moisture leaves it which is why we can’t get the sizes in Oak kiln dried boards as you would in green or air dried oak.
As Oak kiln dried boards are dried out in a kiln rather than left to dry outside they are a lot cleaner than air dried oak and don’t have the splits and checks that beams are naturally supplied with. Although the boards can still move you can seal them to stop moisture getting into the timber which would make them expand and then shrink as they dry back out. If you allow the movement you are likely to find that your boards develop surface cracks and checks.
Normally oak boards are supplied cut to size or planed all round, however, we also provide machining services to provide cladding, decking and other products. When not machined to profile these boards are generally used for interior and exterior joinery. The cut to size boards are rough sawn on all surfaces whereas the planed all round timber is smooth along the section and rough sawn on the two ends (all boards are supplied overlength).
There are two grades that we supply Oak Kiln Dried Boards in Prime and Light Character. Prime is the highest grade of Oak available and is almost knot free (it can contain very small knots, but no large dead knots). Light Character is also high quality timber however it will contain a few knots (which can make it more appealing depending on your own preference and what you are using it for) but again there will be no dead knots.
Can I use Green or Air Dried over Oak Kiln Dried Boards?
Usually not, because they are a very different product. Oak Kiln Dried Boards are suitable for both exterior and interior joinery. So for making furniture, worktops, flooring, machined cladding etc. Whereas air dried and green oak is used predominantly externally and in construction for trusses and beams.
Both these forms of Oak (green and air dried) are excellent for construction because even as the timber moves and splits and cracks it keeps its structural integrity. Green Oak will over time dry out so surface checks will appear and the wood will split along the surface. Air dried Oak on the other hand will already have these splits and cracks and although it is structurally sound will not appear brand new (mainly because it isn’t). The Oak could also have started or already turned silver grey as it has been left outside to dry.
When choosing between Kiln Dried Oak, Air Dried Oak and Green Oak you need to know how the wood will behave once you have used it and which behaviour is what you need. If you are using the timber for joinery then Kiln Dried is the way to go, if you are using the wood for construction but don’t want it to move so much after you have brought it then air dried is what you need and finally if you want a clean piece of timber for construction Green Oak is the way to go.