Sauna wood guide: cedar vs hemlock vs basswood vs spruce vs thermowood
The wood is most of what you see, smell and touch in a sauna, and it's a bigger part of the price than people expect. Here's what each species is good for, and which one to pick for your situation.
At a glance
| Wood | Scent | Rot and moisture resistance | Cost | Best for |
|---|---|---|---|---|
| Western red cedar | Strong, pleasant | Excellent | High | Outdoor saunas, traditional saunas, anyone who wants the classic smell |
| Canadian hemlock | Very light | Fair (indoors fine) | Low-mid | Indoor infrared cabins; the budget standard |
| Basswood | Almost none | Fair (indoors) | Mid | Allergy- or scent-sensitive buyers; premium infrared |
| Nordic spruce / white spruce | Mild, resinous | Fair-good | Low-mid | Traditional Finnish-style interiors, benches excluded |
| Aspen / alder | None / mild | Fair | Mid | Benches (no resin, stays cool), Finnish interiors |
| Thermowood (heat-treated spruce, ash or aspen) | Mild, toasty | Excellent | Mid-high | Outdoor cladding, modern look, benches |
| Eucalyptus | Light | Fair | Mid | Some infrared brands; hard, fine grain |
Each wood, honestly
Western red cedar
The traditional North American sauna wood. Naturally rot- and insect-resistant thanks to its oils, so it's the default for outdoor barrels and cabins. Smells wonderful to most people, strongly for the first months, then faintly for years. Soft, so it dents; some people find the scent too much in a small infrared box, and a small number are sensitive to it. Costs more than hemlock, and prices rose sharply in the early 2020s. If you want a sauna that looks and smells like a sauna, this is it.
Canadian hemlock
What most mid-range and budget infrared cabins are built from. Pale, straight-grained, hard enough, nearly scent-free, and cheap. Not rot-resistant, which doesn't matter indoors where infrared runs dry. JNH, many Dynamic and Golden Designs models, and plenty of Amazon cabins use it. Perfectly good for an indoor infrared sauna; wrong for anything outdoors or wet.
Basswood
The premium answer to "I don't want any smell." Clearlight's Sanctuary and several high-end infrared lines offer it specifically for people with allergies or chemical sensitivities. Light-colored, soft, uniform, no resin, no aroma. It's a little more expensive than hemlock and a little less durable than cedar; indoors, that's irrelevant.
Spruce and pine
The wall and ceiling wood of most Finnish saunas. Cheap, light, mild-smelling. The catch is resin: knots can weep sap at high temperature, which is why Finnish saunas use spruce for walls but aspen, alder or thermowood for benches you sit on. Fine for traditional saunas, rare in infrared.
Aspen and alder
Resin-free hardwoods that stay cooler to the touch, so they're the classic Finnish bench wood. Aspen is pale and nearly scentless; alder is reddish and warmer-looking. If a traditional sauna offers an upgrade to aspen benches, it's worth it.
Thermowood
Spruce, ash or aspen that's been heat-treated at 350-450°F in a kiln, which caramelizes the sugars, drives out moisture, and makes it far more stable and rot-resistant without chemicals. Darker, brown tones; a subtle toasty smell; costs more than untreated wood but less than cedar in many markets. Increasingly the choice for outdoor cladding on modern cube saunas (Redwood Outdoors, Sweat Kingdom and others use it). Heat treatment makes it more brittle, so screws need pilot holes; not your problem unless you're building one.
Eucalyptus
A handful of infrared brands use it for a fine, hard, pale cabinet. Little scent, looks like a lighter hemlock, holds up well indoors. Nothing wrong with it; nothing special either.
Which one for you
- Outdoor: cedar or thermowood. Anything else will need constant finishing and still won't last.
- Indoor infrared, on a budget: hemlock. It's what the price buys and it's fine.
- Indoor infrared, scent-sensitive or allergy-prone: basswood, then hemlock.
- Indoor infrared, want the sauna smell: cedar. Give it a month to mellow.
- Traditional Finnish-style: spruce or cedar walls, aspen or alder benches.
Three things that matter more than species
- Thickness. Barrel staves and cabin walls run from about 1.4 to 1.75 inches; thicker holds heat better and warps less. Infrared cabinets are typically 7-12mm tongue-and-groove over a frame; thin panels feel flimsy.
- Grade. "Clear" or "A-grade" means no knots; knots are cosmetic on walls and a sap risk on benches.
- Finish. Interiors should be bare or oiled with sauna-specific oil, never varnished. See maintenance for why.