The secret to stable building materials is stable moisture content, and that means kiln drying timber to an
'Equilibrium Moisture Content' of
roughly 12%. This involves the measured removal of two types of moisture content, the first being 'free water' and the second being 'bound water.' The point at which all 'free water' is removed is known as the 'Fibre Saturation Point' and drying timber beyond this level strengthens its fibres, creating a construction material that people often forget is actually stronger than steel and concrete.
A weighting game
Every kiln 'charge' is weighed down with a slab of heavy metal which prevents the timber from changing shape as it releases moisture. Once a charge is ready, it's loaded into place with the help of a kiln car.
A kiln charge being loaded
Turning up the heat
The kilns are heated by a network of pipes that ferry hot oil back and forth between the heat plant and our 7 kilns, aiming for a consistent internal air temperature of 190ºC to most efficiently remove moisture. Clouds of white steam billow into the air as cool dry air is fanned from one end to the other, periodically reversing direction to ensure even drying throughout.
3 hours later
After a stint at 190ºC, a standard kiln charge is ready to begin a phase of equalisation. When doors to the kiln open, a thick blackened residue of vaporised tree sap is left as a reminder of its time with us.
sustainability in focus
Powered by by-product
It takes a lot of energy to power a kiln, but instead of burning coal like in a steel smelter, we power our kilns with bio-fuel pellets made from our own sawdust. It's just one of the factors that add up to timber having one of the lowest embodied energies of all construction materials.
Durability takes time
Some argue it's an art, but our team argue they have it down to a fine science. Either way, there's no argument the kiln-drying process is the biggest bottleneck in any mill, and for many of our competitors the temptation to rush the process is too great. We take that little bit extra time to ensure we get the science right... because that little extra care means a whole lot extra durability.
