What is Thermowood?

Developed in Finland during the 1990s, the ThermoWood® process is a patented method that subjects timber to high temperatures ranging from 180°C to 230°C in a controlled steam environment. This treatment modifies the wood’s chemical and physical structure, enhancing its durability, stability, and resistance to decay. The process is meticulously standardised, ensuring consistent quality across all batches.

With a Durability Class 2, it is comparable to Oak, and has a 15+ year lifespan when used externally above ground level.

Through exposure to heat and steam in an oxygen-free environment, the chemical composition of the wood changes. 

During the process, the hemicellulose, a complex branched structure composed of sugar monomers found in cell walls, breaks down. The process alters the lignin and cellulose structures, improving the timber’s resistance to decay, enhancing durability, and increasing dimensional stability.