Understanding oak frames
The properties of an oak frame
What is green oak?
Green oak is the timber from an oak tree that has been felled in the last 18 months, and as such has not dried out, so has a high moisture content. Green oak is used in oak framing because it is very strong, very durable and easy to work with. Our oak and softwood is sourced from sustainable forests and is fully certified and-traceable. We use only a handful of specialist beam oak sawmills on the continent, so we can be sure our timbers are from sustainable forests and that our rigid standards are maintained.
Will my oak frame shrink? And by how much?
Green oak has a relatively high moisture content and will shrink, split and move as it dries out; these changes are an intrinsic part of green oak-framing, and a well-designed frame will allow for them. The effects of shrinkage vary, and are dependant on various factors: starting moisture content; environment; grain orientation and surface finishes. Typically, the timbers will have no obvious shrinkage parallel to the grain, and will remain the same length. Across the grain, however, the oak will shrink by about 8%. The frame design, structural calculations and joints are all developed to allow for this shrinkage.
Is splitting a structural defect?
No. The oak frame is weakest when it is first erected and becomes stronger as drying occurs. As the oak dries the timber becomes harder and stronger. During the natural drying process, stresses occur within the timber; the splitting is evidence of the stresses being released.
Will the frame leak when the timbers split and move?
We have TRADA accreditation on our entire building system, which includes our infill panels. The panel’s gaskets and seals are designed to move with the oak and maintain the weather seal.
How air tight is the oak frame?
The airtightness of the frame depends on the detailing and the quality of workmanship on site. We at Welsh Oak Frame are very proud of our 100% track record for airtightness.
Post and beam oak frames
In post and beam oak framing the upright posts support horizontal beams and are connected with traditional joinery. The weight is taken by the horizontal members resting on the vertical posts, and the shell of the building is suspended around the frame. This style of oak frame construction allows for endless design possibilities and is usually chosen because of its unique charm and character, but it also represents real cost-effectiveness because the need for other structural materials is reduced.
Traditional timber framing
In traditional timber framing the frame is made up of a series of beams, connected and secured with mortice and tenon joints, with the weight of the frame transferred through the vertical timbers. In the UK we are surrounded by many fine examples of medieval timber frame construction; a testament to the integrity and longevity of this method of timber frame construction. Though traditional, the many possible design and layout options make this frame type the perfect solution for modern building projects.
Oak frames and the environment
Oak is a renewable carbon neutral building product and the emissions created in the conversion, transportation and fabrication of the oak frame is offset by the long life span of the finished building.
Not only is oak more thermally efficient than other building materials, it also has the lowest carbon footprint.
Protecting the environment is increasingly a concern therefore it is reassuring to know that oak is a sustainable building material with low environmental impact.