Choosing the Right Wood for Your Custom Sauna

When designing custom saunas with potential clients, one of the first and most important decisions we make together is wood selection.

It shapes how the sauna looks, how it feels against your skin, and how it last under intense heat and humidity over the years. This guide walks through every wood option we offer, why we recommend what we do, and how to think about matching wood choice to your specific sauna vision.

A sauna is one of the most thermally demanding environments you can put wood in. In our saunas, temperatures regularly hit 170–205°F. Humidity swings from dry to saturated when you throw water on the stones. The wood expands, contracts, absorbs moisture, and releases it — hundreds of times over its lifetime.

Here is what we looked for when selecting our collection of sauna wood:

1. Low thermal conductivity - it shouldn't burn when you sit on it

2. Low resin content - resins can off-gas at heat and cause the sauna to smell bad

3. Dimensional stability - it needs to expand and contract without warping or cracking

4. Moisture resistance - it will get wet, repeatedly

5. Smooth grain - no splinters against your bare skin

6. Beautiful aging - a good sauna wood develops character over time

The Wood We Build with Most: Western Red Cedar

About nine out of ten of our builds end up in western red cedar, and there are very good reasons for that.

Cedar is simply one of the most naturally sauna-suited woods that exists. Its natural oils give it resistance to moisture, mold, and decay — all critical in an environment that flips back and forth between intense heat and humidity repeatedly. It expands and contracts without warping or cracking over years of use. It has low thermal conductivity, so benches stay a comfortable temperature against bare skin even at high temperatures.

But the thing that makes cedar genuinely special — is the sensory experience. The fragrance that fills the room when cedar heats up adds to the experience and becomes part of the ritual. The red and brown tones and natural grain are visually stunning. Lastly, it ages beautifully — deepening and darkening over years into something that looks lived-in. Cedar also performs equally well for both interior and exterior applications. For outdoor saunas especially, its natural decay resistance is invaluable — it weathers gracefully whether you maintain it with oil to preserve the color or leave it to silver naturally.

If you want one wood that does everything well and feels and smells extraordinary — cedar is it.

Best for: Almost everything. Indoor and outdoor saunas, barrel saunas, traditional and contemporary designs, clients who want a classic sauna experience with proven long-term performance.

One thing to know: Cedar does contain aromatic oils, and very occasionally clients with chemical sensitivities find the scent too intense in an enclosed space. It is rare, but worth knowing. If this is a concern, hemlock is our recommended alternative — it performs comparably with a much more neutral profile.

Alternative Woods We Work With

For clients with specific aesthetic goals, sensitivities, or ideas that call for something different, we offer three excellent alternatives.

Aspen — Clean, White, Scandinavian

Aspen is the classic Nordic sauna wood — almost pure white when fresh, with a minimal, fine grain that gives a sauna a light and airy Scandinavian feel. It is virtually resin-free, stays very cool on the skin, and develops a beautiful soft silver-grey patina over time.

It is an excellent choice for clients who want the interior to feel open and undramatic — where the wood recedes and lets the architecture or the experience speak. It is also a great option for anyone who wants to avoid the cedar scent entirely.

Best for: Minimal, contemporary, or Scandinavian-influenced designs. Clients who prefer a scent-neutral wood. Anyone who loves the simplicity of white-toned wood.

One honest note: Aspen can develop small surface cracks as it dries and seasons over time. This is completely normal, it is simply the wood breathing, and it does not affect structural integrity or performance at all. But if a flawless finish is important to you, it is worth knowing upfront.

Hemlock — The Quiet Performer

Western hemlock does not have the drama of cedar or the Nordic look of aspen, but it is an excellent sauna wood that earns its place. It is very stable dimensionally, has a fine even grain, extremely low resin content, and ages to a warm silver-grey tone. It is also typically more accessible in price than cedar.

For clients who want a clean, calm interior that performs reliably for years without any fuss — hemlock delivers that quietly and consistently. I like hemlock's silvery aged look that

Best for: Clients who prioritize performance and simplicity over bold aesthetics. A great choice when budget is a consideration without wanting to compromise on quality.

One downfall: It can be prone to checking/cracking as it dries, and it doesn't have cedar's natural rot/moisture resistance, so longevity can be shorter in a wet sauna environment.

Thermally Modified Aspen (Thermowood) — The Modern Choice

Thermally modified wood is made by heat-treating aspen at very high temperatures - around 400°F - in a steam environment. This process fundamentally changes the wood's cellular structure, making it dramatically more resistant to moisture absorption and dimensionally more stable than untreated wood.

Thermowood has a rich caramel to dark espresso tone that is completely distinct from anything else we work with. It also has a toasted, almost nutty smell. It is increasingly popular with clients who want a more modern, design-forward sauna interior — darker, moodier, and more dramatic than the lighter Nordic woods. I really prefer thermowood's color to the lighter wood colors. It also performs exceptionally well on exteriors, handling harsher climates with minimal maintenance.

Best for: Contemporary or design-forward saunas. Clients who want a darker, more dramatic aesthetic. Outdoor saunas in demanding climates.

One small downfall: Brittleness. The thermal modification process that makes it stable and rot-resistant also removes moisture from the wood's cell structure, making it noticeably more brittle than untreated wood.

Exterior Woods

The outside of your sauna faces a very different set of demands — UV, rain, snow, freeze-thaw cycles. Our go-to exterior choices are:

Western Red Cedar — the natural oils that make cedar great inside make it equally great outside. Handles moisture cycles and weathering with ease, maintained with oil or left to silver naturally.

Thermowood — its modified structure means very low moisture absorption and excellent long-term stability outdoors. Great for clients who want a dark, contemporary exterior that requires minimal upkeep.

How We Help You Choose

The right wood for your sauna depends on a combination of factors: your aesthetic vision, your climate, whether your sauna is indoor or outdoor, how you use it, your maintenance preferences, and your budget.

When we design a custom sauna together, we walk through all of these considerations and often recommend different woods for different elements — cedar for the benches where comfort matters most, cedar /thermowood for the exterior where decay resistance is critical. There is no single right answer. But there is always a right answer for your particular sauna, your home, and how you want to feel in that space.

If you have questions about wood selection or want to talk through your custom sauna project, we would love to hear from you.

All saunas we build use sustainably sourced timber. We are happy to provide sourcing documentation on request.