Western red cedar is the best all-around sauna wood because it stays cool to the touch, resists moisture and microbial damage, and holds up well over time, while Finnish spruce is a solid and often less expensive alternative that's actually the most common choice in Finland.
If you're building a sauna, the wood you choose matters more than almost any other decision. It affects how the room feels, how it smells, how it holds heat, and how long it lasts. The wrong wood can mean splinters, excessive resin dripping, or a space that gets uncomfortably hot to the touch. The right wood makes the experience something you look forward to every time.
Let me save you some research time. Here is what the evidence and tradition point to.
Cedar: The Gold Standard for a Reason
Western red cedar is the most common sauna wood in North America, and for good reason. It has natural antifungal and antibacterial properties—something the Finnish have known for centuries. The wood contains natural oils called thujaplicins that resist moisture damage and decay. In a room that hits 180°F and 90% humidity repeatedly, that matters.
Cedar also stays cooler to the touch than other woods. This is not a minor detail. When you lean back against a hot wall, you want wood that does not transfer heat aggressively. Cedar has low thermal conductivity, meaning it heats up slower and feels more comfortable against bare skin.
The smell is another factor. Cedar has a distinct, pleasant aroma that many people associate with sauna. But here is the honest tradeoff: that smell fades over time. After a year or two of regular use, the aroma diminishes significantly. Do not buy cedar expecting the scent to last forever.
One practical downside: cedar is softer than other options. It dents and scratches more easily. If you plan to build a high-traffic sauna, expect some wear marks.
Finnish Spruce: What the Finns Actually Use
Here is something that surprises most people. In Finland, where sauna culture runs thousands of years deep, the most common wood is not cedar. It is spruce. Specifically, Norwegian spruce or Finnish spruce.
Spruce has a tight, straight grain that resists warping. It does not drip resin the way pine does, which matters because resin drips at sauna temperatures can burn skin. Spruce also has a mild, clean scent that does not compete with the experience. Some people describe it as almost neutral, which they prefer.
The thermal performance is solid. Spruce holds heat well without becoming uncomfortably hot to touch. It is harder than cedar, so it resists dents better. And it is usually less expensive.
The one thing to watch: spruce is more susceptible to moisture damage than cedar if the sauna is not properly ventilated. If you build with spruce, make sure your ventilation plan is solid.
Alder: The Dark Horse
Alder is less common in North American saunas but popular in Scandinavia. It has a reddish-brown color that darkens beautifully over time. The grain is straight and uniform, which makes it predictable to work with.
Alder has low resin content, so you will not deal with sticky drips. It also has decent thermal properties—not as cool as cedar, but warmer than pine on the skin. The wood absorbs moisture and releases it evenly, which helps regulate humidity swings inside the sauna.
The catch: alder is not as naturally rot-resistant as cedar. You need to maintain proper airflow and avoid standing water on the surface. In a well-designed sauna, that is not an issue. But if your build quality is questionable, alder will show problems faster.
Aspen: The Hypoallergenic Option
Aspen is the wood to choose if anyone using the sauna has respiratory sensitivities or allergies. It has virtually no scent. No oils. No resins. It is about as neutral as wood gets.
Aspen stays cool to the touch, similar to cedar. It does not splinter easily, which matters for bench surfaces where people sit and lie down. The pale color reflects light well, making the space feel brighter.
The tradeoff: aspen is soft. It dents and scratches easily. It also has a shorter lifespan than cedar or spruce in a sauna environment. You will likely need to replace bench surfaces sooner.
What to Avoid
- Do not use pressure-treated lumber. The chemicals used to treat it—typically copper-based compounds—can off-gas at sauna temperatures. You do not want to inhale that.
- Do not use standard pine from the hardware store. It drips resin profusely at high temperatures. That resin can burn skin and leave sticky residue everywhere. Some specialty kiln-dried pine exists specifically for saunas, but standard construction pine is not the same thing.
- Do not use tropical hardwoods like teak or ipe. They look beautiful, but they get dangerously hot. You cannot lean against them. They also have high environmental costs and often come from questionable supply chains.
The Practical Takeaway
If you want the best all-around wood for a sauna, buy Western red cedar. It checks every box: thermal comfort, moisture resistance, durability, and natural antimicrobial properties. It costs more, but a sauna is a long-term investment.
If budget is tighter, Finnish spruce is a legitimate alternative that the Finns themselves prefer for many builds. Just make sure your ventilation is right.
For bench surfaces specifically, consider aspen or alder. These woods stay comfortable against skin and resist splintering better than cedar or spruce.
One more thing: whatever wood you choose, buy kiln-dried lumber. Green or air-dried wood will shrink and crack as the sauna heats and cools. Kiln-dried wood has already stabilized, so it holds its shape over hundreds of heating cycles.
The wood you pick will define how your sauna feels for the next decade. Take the time to get it right. Your back—and your relaxation time—will thank you.
Frequently asked questions
What wood should I avoid in a sauna?
Avoid pressure-treated lumber because its chemical compounds can off-gas at sauna temperatures. Standard construction pine is also a poor choice since it drips resin profusely, which can burn skin and leave sticky residue. Tropical hardwoods like teak or ipe get dangerously hot to the touch and aren't practical for sauna use.
Is cedar or spruce better for a sauna?
Cedar is generally considered the best all-around option due to its natural moisture resistance, low thermal conductivity, and antimicrobial properties. Spruce is a legitimate alternative that's harder than cedar, resists dents better, and is usually less expensive, though it's more susceptible to moisture damage if ventilation isn't done right.
What's the best wood for sauna benches?
Aspen and alder are both good choices for bench surfaces. Aspen has virtually no scent or resins, stays cool to the touch, and doesn't splinter easily, making it a strong option for anyone with respiratory sensitivities. Alder has low resin content and absorbs and releases moisture evenly, though it's not as naturally rot-resistant as cedar.
Does it matter if sauna wood is kiln-dried?
Yes, kiln-dried lumber is strongly recommended regardless of which wood you choose. Green or air-dried wood will shrink and crack as the sauna heats and cools, while kiln-dried wood has already stabilized and holds its shape over hundreds of heating cycles.