Types of European Oak & Grades
Seasoned Green Oak:
Green oak, (seasoned not fresh sawn), is often the best product for construction. When used with traditional mortise and tenon jointing methods the oak will shrink a little (mostly in the girth), these time-tested framing techniques use this to an advantage. As the oak shrinks slowly over time the joints tighten and create a very strong natural & durable bond. The skill and dedication of selecting this timber, in our option, cannot or should not be mechanised. Our green oak logs have been left to settle for a considerable time period (approx 3-5 years in the round), before being hand selected, cut and planed to meet each individual order and purpose. This ensures that the moisture content is low enough to remain stable yet will still benefit from the natural settling period resulting in a stable build that we stand behind. We have no issue in offering lifetime guarantee.
Freshly Sawn Green Oak:
Readily available throughout Europe and many can be tempted by the cheap cost. At Apex Oak Frames Ltd, we NEVER use freshly sawn oak. Whilst the price may be cheaper, the quality will definitely suffer. The moisture content of freshly sawn oak is typically much higher than seasoned oak at around, 80% carrying the risk of undesirable twisting, movement and excessive shrinkage, a risk that we would simply do not undertake unless it is specifically requested.
The Characteristics of Green Oak
The unique quality of oak is that it will age and slight cracks or splits will appear over time, adding sophisticated character without compromising the structural integrity. As the timber dries in-situ the oak hardens further and is one of the toughest timber building products available. The proof of this is evident in the historic structures all over Europe that have stood firm for hundreds of years.
Your builder, engineer or architect may have a preference for either Air Dried or Green Oak. It is a matter of preference of the designer, architect or builder and the end use of the timber. We are happy to tailor your quote to any specification.
Air Dried Oak
This uses a natural and environmentally friendly method to dry oak to a moisture content of between 20-30% fluctuating slightly with atmospheric conditions i.e. humidity and temperature. Properly stored oak logs are left to rest from between 5 to 10 years or more with adequate ventilation between the logs which is paramount.
Air dried oak can be described as hard as Iron. Using air dried oak can reduce issues of shrinkage and movement of the wood in the final construction. Whilst experienced oak framers may prefer green oak (not freshly sawn), in order to allow the joints to shrink and tighten, air dried oak can be the preferred choice of some builders and architects.
The lengthier times in production in our workshop and the times involved in drying the oak do add to the price of the finished product. However, it is by no means out of reach of the average builder looking to install these beams. If you are considering this building material we are very happy to provide a comparison quote of both green oak and air dried oak.
Should I use Air Dried Oak?
We use Air Dried Oak predominantly for products like Oak Estate Gates and parts of glazed oak frames. It's important to realise that an oak timber of 250/250 section size will take around 25years to dry to the centre of a large beam. So unless you are using smaller section sizes it is usually a waste of money to use air dried.
Kiln Dried Oak Beams Vs Solar Dried Oak Beams
Oak of this nature is taken and dried in large kilns. Due to the amount of energy required by this process, there are thankfully now producers of solar dried oak of the same quality.
When talking of either kiln dried or solar dried oak the properties of the wood are very similar if not indistinguishable.
Kiln and solar dried oak:
is mostly used for furniture and cabinetry work. It is not usually possible to kiln dry oak with a larger section of about 75-100mm due to the Oaks density.
The moisture contents are minimal and therefore shrinkage and movement reduces however only to a point. All timber will move and adjust to the final inhabited environment.
Kiln or solar dried oak is more expensive and seen as a premium product for specialised projects.
Price on application.
THA | THB | D30 | D40 - EU Strength Grades
A Full Colour Downloadable E-Book on EU Timber Grades with Full Colour Pictures and Great Illustrations. Making the Grade by the Forestry Commission.