Trees contain a considerable amount of water when harvested. Once a tree is cut down and sawn, the wood immediately begins losing its moisture. The rate of moisture loss can be unpredictable due to air temperature and humidity variations.
Green timber exposed to a low temperature and high humidity tends to season at a slower rate versus timber dried at high temperatures and low humidity.
The purpose of seasoning is to uniformly dry the timber with minimal deformities in the shortest amount of time.
Exposing timber to circulating air and controlled heat over a given period of time is called EMC (equilibrium moisture content). Continue reading below to understand the three advantages for building with seasoned wood.
1. Reduced Inception of Decay or Stain Fungi
Seasoned wood dried to a moisture content of less than 20% below the fibre saturation point will ultimately prevent the onset of stain fungi and decay.
Seasoned timber’s decay rate is much slower than green wood, and lasts much longer. Since the decay of timber occurs from attacks of wood-destroying fungi, which feeds off of water, seasoned wood has a higher chance of preservation.
2. Weighs Less
The weight of wood is reduced by about 35% or more when seasoned. With its reduced weight, timber transportation and handling costs are reduced as well.
Freight charges can vary considerably, so the ability to decrease timber weight by 35% to 40% helps keep the retail price of your timber lower.
3. Increased Strength and Stability
As wood dries its stiffness, hardness and resistance to bending increases. In order to minimise dimensional changes, wood should be dried to the moisture content it will assume in use.
The use of green timber in any construction can result in severe deformation as the timber dries. Most species of wood increase their strength characteristics by 50% or more when seasoned.
Choosing Seasoned Timber
Before choosing timber for any building or constructing project, it pays to take the time to learn the characteristics of the wood you are considering. Below is a list of several locally available hardwood timbers that when seasoned, are great choices to build with.
Ironbark – This wood has a colouring of red and is used for outdoor framing, flooring, decking, and handrails.
Merbau/Kwila – Used for framing, flooring, decking, and handrails and has a colouring of brown.
Spotted Gum – Spotted gum is great for flooring, decking, handrails, landscaping and outdoor framing. This wood has mixed colouring.
Blackbutt – This wood is blonde in colour and is popular for decking, outdoor framing, and decking.