Cedar and ThermoWood® are both popular in premium outdoor saunas, but they are not simply two versions of the same material.
Cedar is a wood species valued for its natural appearance, aroma, and durability. ThermoWood® is thermally modified wood: wood whose properties have been changed through a controlled heat-and-steam process.
That distinction matters because the right choice depends on what you value most—traditional character, dimensional stability, weather exposure, maintenance, or the design of the sauna itself.
First: ThermoWood® Is a Process, Not a Wood Species
The International ThermoWood Association defines ThermoWood® as wood modified at elevated temperature with steam and without added chemicals. The process changes the wood’s moisture behavior, improving dimensional stability and resistance to biological degradation.
That means “ThermoWood®” does not tell you the original species by itself. When comparing saunas, look at the manufacturer’s complete construction details rather than treating the trademark as a species name.
You can read more about the process from the International ThermoWood Association.
Why Buyers Choose Cedar
Cedar has a long history in outdoor construction because quality heartwood is naturally resistant to decay and performs well in exposed applications. It is also lightweight, dimensionally stable, and visually distinctive.
Cedar may appeal to you if you value:
- Natural aroma: Cedar’s scent is part of the experience for many sauna owners.
- Warm color and grain: It has a classic North American sauna look.
- Natural outdoor durability: Cedar has long been used for siding, shingles, fencing, and other exterior applications.
- A traditional feel: For some buyers, cedar simply looks and feels like what a sauna should be.
Outdoor cedar will weather over time. Sun, rain, moisture exposure, roof design, finish, and maintenance all affect how it ages. If maintaining the original color matters to you, ask what exterior-care routine the manufacturer recommends.
Why Buyers Choose ThermoWood®
Thermal modification reduces the wood’s equilibrium moisture content and improves dimensional stability. In practical terms, that can mean less movement as humidity and weather conditions change.
ThermoWood® may appeal to you if you value:
- Dimensional stability: Reduced swelling and shrinking can be valuable in changing outdoor conditions.
- Improved resistance to biological degradation: The thermal-modification process changes the wood in ways that improve durability.
- Lower-maintenance expectations: Depending on the product and finish, many buyers choose thermally modified wood because they want stable outdoor material without relying on chemical treatment.
- A darker contemporary appearance: Thermal modification gives wood a richer tone that works well with modern sauna designs.
ThermoWood® still requires proper sauna design, drainage, weather protection, and manufacturer-recommended maintenance. No wood material makes poor installation or standing water irrelevant.
What About Cold, Snow, Rain and Coastal Conditions?
For an outdoor sauna, the wood is only part of the durability story.
Roof construction, flashing, doors, glazing, foundation, drainage, exterior finish, exposure, and the quality of the assembly can matter just as much as the wall material. A well-designed cedar sauna can perform very well outdoors, and a ThermoWood® sauna still needs to be installed correctly.
If your sauna will be fully exposed in a demanding climate, ThermoWood® deserves serious consideration because dimensional stability is one of its defining advantages. If you prefer cedar’s aroma and traditional appearance, cedar remains a strong outdoor option when the sauna is built and maintained for the site.
Cedar vs. ThermoWood®: The Buying Decision
Choose cedar when:
- the natural cedar aroma matters to you;
- you prefer a warm, traditional look;
- you are comfortable following the manufacturer’s exterior-care recommendations; and
- the specific cedar model has the weather protection your installation needs.
Choose ThermoWood® when:
- dimensional stability is a major priority;
- the sauna will see significant seasonal swings or outdoor exposure;
- you prefer a darker, more contemporary appearance; and
- you want thermally modified wood rather than relying only on a naturally durable species.
Do Not Choose on Wood Type Alone
Two outdoor saunas made from different woods may also differ in heater, insulation, roof design, interior dimensions, glass area, electrical needs, warranty, and assembly requirements.
Before choosing between them, compare the complete sauna, not just the material name.
For a broader view of available designs, browse our Outdoor Saunas. If thermally modified wood is your priority, go directly to the ThermoWood® Sauna collection.
Need Help Comparing Two Models?
Send Martin Sauna the two models you are considering and tell us where the sauna will be installed. We can help you compare the materials, size, heater, electrical requirements, weather exposure, and practical differences that matter after the sauna arrives.
