Thermowood – the wood that lasts longest
How heat-treated Nordic spruce becomes a material that withstands winter, summer and daily firing for decades.
Thermowood isn't a species of wood, but a treatment. Ordinary Nordic spruce goes into a closed kiln at almost 200 °C and is exposed to steam for a day and a half to two days. It sounds simple, and it is – but the result is an entirely different material.
What the heat changes
The cell walls lose their ability to bind water. The wood absorbs far less moisture, it barely moves with the seasons, and it resists rot and fungus. The colour turns a deep caramel, with no stain or oil at all.
Why we build in it
A sauna lives at the extremes – hot, cold, humid, dry, several times a week, all year round. A material that doesn't move keeps its shape. A thermowood structure that's set up correctly lasts 25–35 years with minimal maintenance. That's why all our models are thermowood.