How to Choose the Right Wood for Your Sauna

How to Choose the Right Wood for Your Sauna

The wood you pick for your sauna affects everything: how long it lasts, how it smells, how it handles moisture, how hot the benches get against your skin, and what the whole space feels like when you walk in. It's not just an aesthetic choice. Pick the wrong wood and you'll be dealing with warping, cracking, mold, or splinters within a couple of years.

Here's a straightforward comparison of the most common sauna woods so you can choose the one that fits your setup, your climate, and your budget.

Western Red Cedar

Cedar is the most popular sauna wood in North America, and for good reason. It's naturally resistant to rot, insects, and moisture. It has a warm, pleasant aroma that most people love. The color is rich and varied - reddish brown with natural grain patterns that look great without staining or finishing.

Cedar also has low thermal conductivity, which means the benches won't burn your skin even at high temperatures. It's dimensionally stable, meaning it resists warping and shrinking as temperature and humidity fluctuate inside the sauna.

The downside? Cost. Cedar is the most expensive common sauna wood. But for outdoor saunas where weather exposure is a factor, it's the smartest long-term investment.

Best for:

• Outdoor saunas and barrel saunas
• Humid climates where moisture resistance matters most
• Buyers who want the classic sauna look and smell

Canadian Hemlock

Hemlock is the budget-friendly alternative to cedar. It's a light-colored softwood with a clean, uniform appearance and virtually no smell. The grain is tight and even, giving it a modern, minimalist look that many people prefer over cedar's rustic character.

Hemlock handles heat well and has decent moisture resistance for indoor use. However, it's less naturally rot-resistant than cedar, which makes it a poor choice for outdoor saunas that face rain, snow, and ground moisture without protection.

Best for:

• Indoor saunas where weather exposure isn't a concern
• Budget-conscious builds
• People who prefer a light, neutral wood appearance

Nordic Spruce (White Spruce)

Spruce is the traditional wood used in Finnish saunas. It's light in color, has a tight, even grain, and a subtle natural fragrance. Finnish sauna builders have used it for generations, and it performs well in the hot-cold cycling of traditional sauna use.

Spruce is softer than cedar and less naturally rot-resistant, so it needs more care in outdoor installations. It can be treated with sauna-safe wood treatment to extend its outdoor life, but it won't match cedar's natural durability without that maintenance.

Best for:

• Traditional Finnish-style builds
• Indoor or covered outdoor installations
• Authenticity-focused sauna enthusiasts

Thermally Modified Wood

Thermal modification is a process where wood is heated to 400-500F in a controlled, oxygen-free environment. This permanently changes the wood's cellular structure, making it significantly more resistant to moisture, rot, and insect damage - without any chemical treatments.

Thermally modified timber (often spruce, pine, or ash) has a darker, richer color and enhanced dimensional stability. It performs like a premium hardwood but comes from sustainable softwood sources. The process reduces the wood's ability to absorb water by up to 50%, making it excellent for outdoor use.

The tradeoff: thermally modified wood can be more brittle than untreated wood, so it needs careful handling during assembly. Screw holes should be pre-drilled to prevent splitting.

Best for:

• Outdoor saunas where maximum durability is needed
• Chemical-free builds
• Modern aesthetic preferences (darker tones)

Aspen

Aspen is a lightweight hardwood with almost no scent, making it ideal for people sensitive to wood aromas. It has very low thermal conductivity - even lower than cedar - which means benches stay comfortable at the highest temperatures. It's also hypoallergenic, which is why it's commonly used in European sauna bench construction.

Aspen is best used for interior components (benches, backrests, headrests) rather than exterior walls. It doesn't hold up well to outdoor moisture and will deteriorate quickly without protection.

Best for:

• Bench surfaces and interior trim
• People with wood allergies or scent sensitivity
• High-temperature traditional saunas (190F+)

Quick Comparison Table

What About Treatments and Finishes?

Inside the sauna, use only sauna-specific wood treatments - or nothing at all. Standard wood stains, paints, and polyurethane off-gas toxic fumes at sauna temperatures. Many sauna owners leave interior wood untreated and let it develop a natural patina over time.

For exterior surfaces on outdoor saunas, a UV-protective wood oil or stain is recommended to prevent graying and weathering. Reapply annually. For more on keeping your wood in shape, read our sauna wood care guide.

The Bottom Line

For outdoor saunas, go with western red cedar or thermally modified wood. For indoor saunas on a budget, Canadian hemlock is perfectly fine. For benches specifically, aspen is hard to beat on comfort. And if you're building a traditional Finnish sauna, spruce is the authentic choice.

Browse our outdoor sauna and indoor sauna collections to see these wood types in action. Every product page lists the wood species so you know exactly what you're getting.