What is thermally modified wood and what can it be used for?

We often hear the term but don’t really understand what it means. Its a process where wood is altered from its original makeup by using a combination of heat and steam with the absence of oxygen. This changes the cell structure of the wood in order to increase the woods durability. Lack of oxygen prevents the wood from burning.

Thermowood Heat Treatment can be divided into three phases:

Phase 1: Drying; Temperature of wood is rapidly raised to 100°C. Following this rapid heating, temperature is increased steadily to 130°C, the wood is dried, and its moisture content is reduced to zero.

Phase 2: Heat Treatment; Temperature is increased to 180°C or to 212°C using steam. After the target level is reached, temperature remains constant for 2 to 3 hours.

Novawood Exterior Ash SidingPhase 3: Cooling and Conditioning; In the final stage, temperature is reduced to 80-90°C by water spray. This process continues until the moisture content reaches 4 to 6%.

Thermowood method, brand and logo can only by the used by members of the International Thermowood Association.

The main advantage of thermally modifying wood is the increased durability it brings to the wood allowing the wood to be used in a variety of applications that require high durability such as wood decking and wood siding.

The three main species we use in our decking and siding products are North American Ash, European Pine and a African species called Iroko.

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