Western Red Cedar vs Thermowood

August 22, 2026 by Procraft

Western red cedar is naturally rot-resistant and carries the classic sauna aroma. Thermowood is ordinary softwood baked in a kiln until it becomes stable and rot-resistant, which leaves it darker and almost scentless. Both last outdoors. Cedar wins on smell and character, thermowood on price and on a very even, dark appearance.

What thermowood actually is

Thermowood is not a species, it is a process. Softwood, often spruce or pine, is heated in a kiln to a high temperature with limited oxygen. That cooking changes the wood: it drives out moisture, breaks down the sugars that fungus feeds on, and leaves the board more dimensionally stable and much more resistant to rot than it started. It comes out an even brown, darker than it went in.

Where thermowood is strong

• Very stable. The heat treatment reduces how much the wood moves with humidity.
• Rot-resistant without chemical preservatives.
• Even, dark colour right through, which some people prefer.
• Usually cheaper than cedar.

Where thermowood gives something up

• Almost no aroma. The kiln drives off the natural compounds, so you lose the smell entirely. For a lot of sauna buyers this is the deciding point.
• More brittle. The same process that stabilises the wood makes it harder and more prone to splitting, so it needs care when fastened.
• Uniform look. Even colour is a plus to some and flat-looking to others. Cedar has more variation and character.
• Colour fades too. Thermowood greys in sunlight like other woods if left unfinished, so it is not maintenance-free either.

Where cedar is strong

• The aroma, which is inseparable from the sauna experience for most people.
• Naturally rot-resistant with no processing at all.
• Warm colour and real grain character.
• Comfortable to sit on, low density so it stays cool to the touch.
• A long track record in outdoor saunas in this climate.

Which should you pick

If the smell and look of real cedar matter to you, pick cedar, and accept that it costs more. If you want a dark, very uniform, stable exterior at a lower price and you do not care about aroma, thermowood is a legitimate choice and it will last outdoors. There is no wrong answer here, only a preference about scent, character and budget.

What we use

We build with Western red cedar. The reasoning is on our Western red cedar page, and there is a separate comparison with hemlock.

Procraft builds Western red cedar saunas and makes four CSA-approved electric sauna heaters from 4.5kW to 9kW. See the heaters, read about Western red cedar, or see how installation works.