Cedar, Nordic Spruce, and Aspen are the best woods for building a sauna because they stay cool to the touch at high temperatures, resist moisture without chemical treatments, and won't release resin or sticky compounds when heated. Hemlock works well for walls and ceilings on a tighter budget.
You're building a sauna. You've already done the hard part—committing to the project. Now you're staring at lumber options, and every wood supplier has a different opinion. Cedar, spruce, hemlock, pine, aspen. Some say cedar is the only choice. Others say it's overpriced.
Here's what actually matters for sauna wood, and which species perform best.
Why wood choice matters for your health
The wood in a sauna isn't just aesthetic. It's the surface your skin touches at 180°F. It's what you're breathing as the heat rises. It absorbs your sweat and releases moisture back into the air. The wrong wood can splinter, overheat, off-gas, or rot within a year.
For a traditional Finnish sauna—the kind linked to the cardiovascular benefits we've covered in previous posts—the wood needs to do four things:
- Stay cool to the touch at high temperatures (low thermal conductivity)
- Resist moisture and decay without chemical treatments
- Not release resin or volatile compounds when heated
- Feel comfortable against bare skin (no splinters, no sticky surfaces)
Cedar: the gold standard, but not the only option
Western Red Cedar is the most common sauna wood in North America, and for good reason. It has natural oils that resist moisture and decay. It stays cool at high temperatures. It has a distinct, pleasant smell that most people associate with saunas.
The research backs the practical experience. Cedar contains thujaplicins, natural compounds with antifungal and antibacterial properties (Morita et al., 2007, Journal of Wood Science). That means the wood resists the mold and mildew that can develop in a high-humidity environment.
The downside: Cedar is expensive. A full cedar sauna can cost 30-50% more than a pine build. The smell fades over time. And some people find the aroma too strong, especially in enclosed spaces.
Best use: Benches, wall paneling, and ceiling. Cedar is the safest choice for surfaces you touch directly.
Nordic Spruce: the Finnish standard
If you've ever been to a traditional Finnish sauna, you sat on Nordic Spruce. Finland grows millions of cubic meters of it annually. It's the default wood in the country that invented modern sauna culture.
Spruce has a tight, even grain that resists splintering. It has low thermal conductivity—meaning it stays cooler than pine at the same temperature. It has almost no resin, so you won't get sticky patches or that burning-pine-sap smell when the heat cranks up.
A 2019 study in Forest Products Journal compared thermal properties of common sauna woods. Spruce had the lowest heat transfer rate among softwoods tested, meaning it stays more comfortable against skin at high temperatures.
The downside: Spruce is less rot-resistant than cedar. In a properly ventilated sauna, this isn't an issue. But if your sauna has moisture problems, spruce will degrade faster than cedar.
Best use: Benches, walls, and ceilings. Spruce is the best all-around choice if you want traditional performance without the cedar price tag.
Aspen: the underrated option
Aspen is a hardwood that behaves like a softwood in a sauna. It has a very tight grain, almost no odor, and stays remarkably cool. It's the wood of choice in many high-end custom saunas in Europe.
What makes aspen unique: it doesn't darken or discolor over time like cedar or spruce. It stays pale and clean-looking for years. It also has very low resin content, so no sticky surfaces.
The downside: Aspen is softer than cedar and can dent or scratch more easily. It's also less available in some regions, which can drive up cost.
Best use: Benches, footrests, and backrests. Aspen is excellent for surfaces you sit or lie on.
Hemlock: the budget-friendly workhorse
Eastern Hemlock is often recommended as a cedar alternative. It's light, straight-grained, and takes stain well. It has moderate rot resistance and stays relatively cool.
The catch: Hemlock can splinter if not properly sanded. It also has a tendency to check (develop small cracks) as it dries. In a sauna environment, those cracks can trap moisture and become breeding grounds for bacteria if the sauna isn't cleaned regularly.
Best use: Walls and ceilings. Not recommended for benches unless you're willing to sand and maintain them regularly.
What to avoid
Pine is the most common mistake. Pine is cheap and widely available. But it's high in resin, which means at sauna temperatures, you'll get sticky surfaces and a strong pine smell that some people find overwhelming. The resin can also drip, creating hot spots that can burn skin. Avoid it for any surface you'll touch.
Pressure-treated lumber is a health risk. The chemicals used to treat wood for outdoor use (copper, chromium, arsenic in older treatments) can off-gas at high temperatures. Never use pressure-treated wood inside a sauna.
Oak and other dense hardwoods conduct heat too well. Oak benches get painfully hot. Stick to woods with low thermal conductivity.
Practical protocol for your build
If you're building now, here's the straightforward recommendation:
- Benches: Cedar or Nordic Spruce
- Walls: Spruce or Hemlock
- Ceiling: Spruce or Cedar
- Floor: Ceramic tile or cedar slats (concrete or tile is better than wood for moisture management)
One note: whatever wood you choose, make sure it's kiln-dried. Green or air-dried wood will shrink and crack as the sauna heats and dries it out. Kiln-dried wood has already been through that process and will hold its shape.
The takeaway
The best wood for your sauna depends on your budget and how much maintenance you want to do. Cedar is the safest, most forgiving option. Spruce is the traditional choice with proven performance. Aspen is the premium alternative for longevity and aesthetics. Hemlock works for walls if you're on a tight budget.
Avoid pine, pressure-treated lumber, and dense hardwoods. Kiln-dry everything. And if you're unsure, ask a local sauna builder what grows well in your region—local species that match these properties often cost less than imported wood.
A well-built sauna with the right wood will last decades. The research on cardiovascular benefits, heat shock protein activation, and recovery is only as good as the environment you're sitting in. Choose the wood that lets you stay in that heat long enough to get the benefits.
Frequently asked questions
Is cedar the best wood for sauna benches?
Cedar is widely considered the safest choice for surfaces you touch directly, including benches, wall paneling, and ceilings. It contains natural compounds with antifungal and antibacterial properties, which helps it resist the mold and mildew that build up in high-humidity environments. The main drawback is cost, as a full cedar build can run 30 to 50 percent more than a pine build.
What wood do traditional Finnish saunas use?
Traditional Finnish saunas are typically built with Nordic Spruce, which is the default wood in the country that developed modern sauna culture. Spruce has a tight, even grain that resists splintering and a low heat transfer rate, meaning it stays more comfortable against skin at high temperatures. It's the best all-around option if you want traditional performance without the cedar price tag.
Can you use pine wood in a sauna?
Pine is not recommended for any surface you'll touch inside a sauna. It's high in resin, which causes sticky surfaces and a strong smell at sauna temperatures, and the resin can drip and create hot spots that may burn skin. It's widely available and cheap, but those advantages don't outweigh the practical problems.
What wood should you avoid when building a sauna?
Avoid pine, pressure-treated lumber, and dense hardwoods like oak. Pressure-treated wood can off-gas harmful chemicals at high temperatures, making it a genuine health risk inside a sauna. Dense hardwoods conduct heat too well and make benches painfully hot, so it's best to stick with low-thermal-conductivity woods throughout the build.