Why Cedarwood Is the Best for a Sauna: An Engineer’s Honest Take

If you’re researching sauna materials, you’ve probably seen a dozen different opinions about which wood is “best.” Some people swear by hemlock. Others argue for Nordic spruce. A few outliers will tell you about exotic woods you’ve never heard of.

But here’s the truth from someone who’s built over 3,000 custom saunas: cedarwood is the best for a sauna, and I’m going to explain exactly why with real data, practical experience, and the kind of technical detail that actually matters when you’re making a $10,000+ investment in your health.

I’m not saying this because it sounds good. I’m saying it because after 11 years of building saunas professionally, testing materials, dealing with warranty issues, and listening to feedback from thousands of customers, cedar has proven itself time and time again. And not just any cedar—Western Red Cedar specifically.

Let me break down why.

The Science Behind Why Cedar Works in High-Heat Environments

Wood selection for a sauna isn’t just about aesthetics. It’s about thermal properties, moisture resistance, dimensional stability, and long-term durability under extreme conditions. A sauna cycles between ambient temperature and 140-160°F (or higher for traditional saunas), often multiple times per day. That’s a brutal environment for wood.

Cedar handles this better than virtually any other softwood, and here’s why.

Thermal Conductivity: Why Cedar Doesn’t Burn You

Cedar has a lower thermal conductivity than most other sauna woods. This matters more than people realize.

When you sit on a hemlock or pine bench that’s been heating for 20 minutes, the wood absorbs and retains more heat. Touch it, and you’ll feel it. Sit on it without a towel, and you’ll definitely feel it. Cedar, by contrast, stays cooler to the touch even at the same ambient temperature.

This isn’t subjective. It’s measurable. Cedar’s thermal conductivity is approximately 0.11 W/mK (watts per meter-kelvin), compared to hemlock at around 0.13 W/mK. That difference might sound small, but in a high-heat environment, it translates to a noticeably more comfortable surface.

You can sit directly on a cedar bench without a towel. Try that with most other woods and you’re going to be uncomfortable fast.

Natural Oils and Aromatic Compounds

Western Red Cedar contains natural oils—primarily thujaplicins—that give it that distinctive, calming aroma. But these oils do more than smell good. They act as natural preservatives that protect the wood from moisture, bacteria, and fungal growth.

In a sauna, you’re dealing with heat, humidity (especially if you’re pouring water on rocks or using steam), and human sweat. That’s a perfect recipe for mold and mildew in lesser woods. Cedar resists this naturally without any chemical treatment.

The aroma itself is part of the experience. It’s subtle, not overpowering, and for many people (myself included), it’s deeply relaxing. There’s a reason cedarwood essential oil is marketed for stress relief—there’s actual therapeutic value in the scent.

Moisture Resistance and Dimensional Stability

Here’s where cedar really separates itself from other woods.

Wood expands when it absorbs moisture and contracts when it dries. In a sauna—where you’re cycling between dry heat, humidity from steam or water on rocks, and then cooling down—this expansion and contraction happens constantly. Over time, woods that aren’t dimensionally stable will warp, crack, or develop gaps.

Cedar has excellent dimensional stability. It absorbs less moisture than most softwoods, and when it does absorb moisture, it expands and contracts minimally. This means your sauna stays tight, the benches stay flat, and you’re not dealing with structural issues five years down the road.

I’ve seen hemlock saunas warp within two years of moderate use. I’ve yet to see a properly built Western Red Cedar sauna have the same problem.

Durability: How Cedar Stands Up Over Time

Let’s talk longevity, because this is where a lot of sauna companies gloss over the truth.

Rot Resistance

Cedar is naturally rot-resistant. The same thujaplicins that create the aroma also make cedar inherently hostile to the fungi that cause wood rot. This is why cedar is used for outdoor decking, fencing, and siding in wet climates—it just doesn’t rot the way other woods do.

In a sauna, where moisture is a constant factor, this rot resistance is critical. You’re not applying sealants or finishes inside a sauna (those would off-gas toxic fumes when heated), so the wood needs to protect itself. Cedar does.

Insect Resistance

Cedar is also naturally insect-resistant. Termites, carpenter ants, and other wood-boring insects avoid it. Again, this comes down to those natural oils. For a sauna—especially one installed in a basement, garage, or anywhere insects might be present—this is a huge advantage.

Aging Gracefully

Here’s something most people don’t consider: how does the wood look after years of use?

Cedar ages beautifully. Over time, it develops a rich patina. The color deepens slightly, and the wood takes on character. It doesn’t look “worn out.” It looks seasoned.

Compare that to pine or spruce, which can start to look tired and discolored after heavy use. Or hemlock, which tends to darken unevenly and can develop stains from sweat and minerals in the water if you’re pouring on rocks.

I’ve been inside 10-year-old cedar saunas that still look and smell fantastic. That’s not marketing hype. That’s just what happens when you use the right material.

Why Western Red Cedar Specifically

Not all cedar is created equal. There are dozens of species called “cedar,” but when I say cedarwood is the best for a sauna, I’m specifically talking about Western Red Cedar (Thuja plicata).

Geographic Advantage

Western Red Cedar grows in the Pacific Northwest—British Columbia, Washington, Oregon. The climate there is cool and wet, which produces slow-growing trees with tight grain patterns and high natural oil content. This makes the wood denser, more stable, and more aromatic than cedar grown in other regions.

Clear vs. Knotty Grades

Within Western Red Cedar, there are different grades. “Clear” cedar has minimal knots and a consistent grain. “Knotty” cedar has visible knots throughout.

For saunas, I use clear grades on benches and backrests—anywhere the user is in direct contact with the wood—and knotty grades for walls and ceilings. The knots add visual interest, but they also create hot spots (knots are denser and conduct heat differently), so you don’t want them where you’re sitting or leaning.

This is one area where you get what you pay for. Clear Western Red Cedar costs significantly more than knotty grades or lower-quality cedar, but the difference in user experience is real.

Sustainability

Western Red Cedar is sustainably harvested. The forests it comes from are managed with long-term yield in mind, and the wood is a renewable resource when harvested responsibly. For people who care about environmental impact (and you should), this matters.

Compare that to exotic hardwoods, some of which come from questionable sources and contribute to deforestation. Or even to hemlock and spruce, which are often clear-cut in less regulated areas.

The Practical Reality: What Actually Matters When You Use Your Sauna

All the technical specs in the world don’t matter if the sauna isn’t comfortable to use. So let’s talk about the practical experience of being inside a cedar sauna versus other woods.

The Sensory Experience

When you step into a cedar sauna, you smell it immediately. That warm, woody, slightly sweet aroma is unmistakable. It’s calming. It signals to your brain that you’re entering a space designed for relaxation and recovery.

Other woods either smell like nothing (hemlock) or smell faintly of pine resin (pine, spruce), which can be pleasant but isn’t as therapeutically associated with relaxation.

The visual warmth of cedar also contributes to the experience. The natural reddish-brown tones create a cozy, inviting atmosphere. Hemlock, by contrast, is pale and can feel sterile. Pine and spruce are yellow-toned and can look cheap if not finished well.

Comfort During Use

Here’s what happens in real-world use:

You’re sitting on a cedar bench for 20-30 minutes. The wood is warm but not hot. You’re not sliding around or feeling sticky. The surface has a slight texture that provides grip without being rough. If you lean back against the wall, the backrest is comfortable even without a towel.

Now imagine the same session on a bench made from a wood that conducts heat more readily, or that has absorbed more moisture and feels damp, or that has rougher grain and feels scratchy against bare skin.

These details add up. A sauna session should feel effortless. The environment should support the experience, not distract from it.

Common Arguments Against Cedar (And Why They’re Wrong)

I’ve heard all the objections to cedar, so let me address them directly.

“Cedar is too expensive.”

Yes, Western Red Cedar costs more than hemlock, pine, or spruce—sometimes significantly more. But here’s the thing: you’re building or buying a sauna that should last 20+ years. Over that timeframe, the difference in material cost is negligible compared to the difference in user experience and durability.

A hemlock sauna might save you $1,500 upfront. But if it warps, develops mold, or just becomes unpleasant to use within 5-10 years, you’ve actually spent more in maintenance, repairs, or replacement.

Pay for quality once, or pay for cheap twice. That’s the rule.

“Hemlock is just as good.”

Hemlock is fine. It’s a serviceable sauna wood. But it’s not as good as cedar, and anyone telling you otherwise either hasn’t used both extensively or has a financial interest in selling hemlock.

Hemlock is less aromatic, less moisture-resistant, less dimensionally stable, and more prone to discoloration over time. It’s cheaper, and for some people, that’s the deciding factor. But it’s not “just as good.”

“You can’t smell the cedar after a few uses anyway.”

This is partially true—you do become somewhat acclimated to the scent. But the aromatic compounds don’t disappear. They’re released every time the wood is heated. And even if you don’t consciously smell it after a while, the therapeutic benefit of those compounds is still present.

More importantly, guests and new users will smell it, and the reaction is almost always positive. It’s part of the experience that makes a cedar sauna special.

“Cedar is harder to clean.”

Cedar is actually easier to clean than most other woods because of its natural oils and tight grain. Sweat and moisture don’t penetrate as deeply, so surface cleaning is usually sufficient.

For routine maintenance, I just wipe down the benches with a damp cloth after heavy use. Every few months, I’ll use a very mild soap solution if needed. That’s it.

Woods like pine and hemlock, which absorb moisture more readily, can develop odors or stains that are harder to remove.

Why I Only Build with Western Red Cedar

I’ve built saunas with hemlock. I’ve built saunas with Nordic spruce. I’ve experimented with different wood combinations.

And after 11 years and over 3,000 custom builds, I only use Western Red Cedar now. Not because it’s trendy. Not because it has better margins (it doesn’t—it’s more expensive to source and work with). But because it’s the right material for the job.

When a customer invests $15,000 to $50,000 in a custom sauna, they deserve a product that will perform flawlessly for decades. Cedar delivers that. It’s predictable. It’s reliable. It’s forgiving of mistakes during installation. It ages well. It requires minimal maintenance.

I’ve had customers reach out after 8, 9, 10 years of daily use to tell me their sauna still looks and functions like new. That doesn’t happen with lesser woods.

The Bottom Line: Making the Right Choice for Your Sauna

If you’re building or buying a sauna, the wood choice is one of the most important decisions you’ll make. It affects comfort, durability, maintenance, aesthetics, and the overall experience every single time you use it.

Cedarwood is the best for a sauna not because of marketing or tradition, but because of measurable performance advantages in thermal conductivity, moisture resistance, dimensional stability, natural preservation, and user comfort.

Yes, it costs more upfront. But over the life of the sauna, it’s the better investment. You’ll spend less time on maintenance, you’ll enjoy the experience more, and the sauna will hold its value better if you ever sell your home.

If you’re serious about sauna therapy—if you plan to use it daily or near-daily for recovery, stress relief, and overall health—don’t compromise on the material. Build with Western Red Cedar. You’ll thank yourself every time you step inside.

And if someone tries to sell you on a “comparable” alternative that’s cheaper, ask them how many saunas they’ve personally built, how long those saunas have been in service, and what their warranty claim rate is. The answers will tell you everything you need to know.

Choose cedar. Your future self will appreciate it.