Sauna Wood Types: Cedar vs Hemlock vs Spruce vs Thermowood

Why Wood Choice Matters

Sauna wood must tolerate repeated heating and humidity without warping, splitting, or leaching resin. It should also stay comfortable to touch, resist rot, and ideally smell pleasant. The species you choose affects look, aroma, durability, maintenance, and price, so it is worth understanding the common options.

Western Red Cedar

Cedar is the premium favorite for its warm reddish tones, natural rot resistance, and signature aroma. It stays dimensionally stable and resists decay well, which makes it popular for both walls and exteriors. The tradeoff is cost positioning at the higher end of the range.

Canadian Hemlock

Hemlock offers a clean, light, even-grained appearance with very little aroma, which appeals to people sensitive to scent. It is reasonably stable and sits in the mid price tier, making it a common choice for indoor cabins where a neutral, modern look is wanted.

Nordic Spruce

Spruce is the traditional Finnish choice, pale and bright with a subtle resin scent. It is widely available and tends to be among the more affordable softwoods. Because untreated spruce can darken and weep some resin over time, it is most at home on walls and ceilings rather than skin-contact surfaces.

Thermowood (Heat-Treated)

Thermowood is timber, often spruce or aspen, that has been heat-treated to remove moisture and resin. The process yields rich brown tones, improved dimensional stability, and strong resistance to warping and decay, which makes it excellent for both interiors and weather-exposed outdoor builds. It typically commands a premium over untreated softwood.

Basswood and Aspen for Benches

Bench and backrest wood touches bare skin, so low heat conduction and no resin are essential.

• Basswood: Soft, pale, splinter-resistant, and nearly scentless, a top pick for benches and a friendly option for those with allergies.
• Aspen: Light colored, smooth, resin-free, and cool to the touch, widely used for benches and trim.
• Avoid: Resinous or dense hardwoods that get scorching hot or weep sap onto skin.

Matching Wood to Budget

A common approach blends species: a stable, attractive wood for walls and a cool, soft wood for benches. Cedar and thermowood anchor the premium end, hemlock the middle, and spruce the value end, all as estimates that vary by supplier and region. If you are planning an exterior build, see our outdoor sauna picks.