Beams are structural elements designed to withstand loads by being resistant to bending. For centuries oak has been the preferred raw material for making beams. The reason being that oak does not get damaged easily. Additionally, oak is aesthetically pleasing and is almost impervious to fire. This is in addition to oak being readily available in the UK. Today, property owners have a decent selection of oak beams to select from, the two most popular being green oak and air dried oak. Both green and air dried oaks are sourced from the same oak variant but undergo different drying processes.

By definition, green oak is unseasoned oak, while air dried oak is as the name suggests dry oak. Air dried oak undergoes three to six months of air drying. As such, air dried oak takes longer to prepare and is considerably pricier than green oak. Another significant difference between green and air dried oak is that green oak has higher water content. Since green oak does not undergo any drying process, it contains more water than air dried. This means green oak is more flexible than air dried oak. However, due to its water content, green oak is not as hard as air dried oak.

While some builders prefer air dried oak to green oak, the latter type of oak is the better of the two especially for constructing beams. Unlike air dried oak, green oak is easier to cut and is, therefore, the better type of wood for making bespoke beams. The problem with air dried wood is that it takes too long to dry and is extremely difficult to cut into custom sizes. Additionally, the notion that green oak compromises a building’s structural integrity is not true. This is because as green oak dries over time the characteristic splits and bends will appear. Green oak is also strong and is impervious to decay. Furthermore, green oak does not require treatments or preservatives and is requires less maintenance than dried oak.

Green oak beams are constructed from freshly cut oak trees aged between 90 and 120 years old. The trees are ordinarily cut during winter when their sap level is lowest. Architects and property owners who prefer dried oak to green oak have three main options to choose from. The first option is kiln drying, which removes approximately 15 % of an oak log’s water content. The second option is air drying, which removes approximately 25% of water. Finally, there is the option of semi-seasoned oak. This type of oak has 20% to 60% of water removed.
In terms of availability, France and the UK are the largest producer of oak in Europe. While imported French oak is cheaper compared to locally grown UK oak, the latter is more available. Additionally, UK oak is easier to inspect since producers of UK oak are based in the country. Additionally, oak sourced from local UK sawmills can be custom made to meet the needs of different clients. Imported oak is harder to cut since the sawmills are not located in the UK.