Please note! All saunas should be treated on the outside just like any other wooden product for a long life. For saunas with a full glass front wall, we recommend treating the plywood frames before installing the glass panels. This will save you time later with masking off the glass.
Thermowood sauna walls sometimes have spruce details such as door frames, sauna feet, finishing planks, etc. These do not necessarily have to be treated, but the customer can choose to have them treated.