Oak has been used for years as a structural component, particularly when it comes to structural support such as what we can find with oak beams. Oak has some excellent qualities which make it ideal as structural support, whether it’s due to its dense and thick structure or its innate strength, or even its natural beauty and aesthetic appeal. But whether you are using green oak for support beams or would like to learn how you can preserve and treat older oak beams, here’s what you need to remember when it comes to the behavior of oak used as a structural component.
- The fact of movement
Fresh or green oak beams lose a lot of water, but as they age, this water loss can result in fissures, depending on how the wood is cut and its size and length. But one fact about oak is movement. Oak beams, particularly older ones, can absorb water, although it doesn’t absorb water as much as other types of wood. But the absorption of water can cause the beams to swell, which is also referred to as a movement, and this can affect the structure’s stability. The good news is that when oak beams are installed internally, the movement can be minimal, especially since the level of internal humidity often remains consistent and low. But if the beams are exposed and are placed outdoors, the humidity surrounding them can fluctuate a lot, particularly with the changing seasons. If your old oak beams have been exposed to a lot of humidity and it has resulted in fungus infestation or mildew issues, you can have this treated by experts in beam restoration who will know what to do to address the problem.
If you are replacing old beams, it is best to use air-dried oak externally because the process of drying will expose it to the elements – thus, it should be better able to handle the humidity levels and achieve ‘balance’. You may also want to consider using European oak because it has already grown in the same climate where it will be used, so it will be more attuned to the local or native environment.
- A chemical reaction with the metal
If you are trying to restore oak beams and are making use of metal fixings, it’s best to use fixings with little iron content, or none at all. Oak is inherently acidic, and when iron combines with the tannins contained in the oak, it can react. This may then cause ugly blue or black stains and even corrosion for the metal fixtures or components. For joins like beam connections, the result can be a weakening of the joints that bear the load. It’s better to use non-ferrous metal fixings or stainless steel fixings for oak wood.
- The way it reacts to fire
Oak is remarkably dense, making it greatly resistant and unaffected by fire, even when it is already dry. Once the wood’s outer surface or layer is already charred, the char will even act as insulation, which slows down the heat transfer to the wood’s core. The burn will be slower and more consistent compared to other types of wood. But you should also use oak pegs rather than metal bolts for your oak beams as they will fare much better if there is a fire.