Cedar vs Hemlock vs Spruce: Sauna Wood Types Compared

By: Reid Hollis

Why Sauna Wood Type Matters More Than You Think

The wood inside your sauna shapes every session. It determines what you smell when the heater reaches temperature, how the bench feels against bare skin, and how the interior looks five or ten years from now. Three species account for the vast majority of commercially built saunas: cedar, hemlock, and spruce.

There is no universally best sauna wood. The right choice depends on where your sauna will live (indoor vs. outdoor), which sauna style you prefer, your budget, and your personal taste. Cedar signals warm luxury and natural durability. Hemlock signals a clean, modern spa aesthetic. Spruce signals Nordic authenticity rooted in Finnish tradition.

This guide covers each species in detail, then provides a comparison table, a practical decision guide, and FAQs to help you match sauna wood types to your specific setup.

Western Red Cedar: The Warm, Aromatic Classic

Western red cedar is the wood most people picture when they think of a sauna. Its rich reddish-brown tones and prominent grain give it immediate visual warmth, and over time, heat cycling deepens the color into a distinctive patina that many owners find more appealing with age.

Cedar's natural oils, including tannins, thujopsene, and cedrol, produce a distinctive scent that is a genuine sensory signature of the sauna experience for many buyers.

From a performance standpoint, cedar excels. According to the Western Red Cedar Lumber Association, the wood has a density of approximately 21 lbs per cubic foot (oven-dry), giving it superior insulating value among commonly available softwoods. Its thermal conductivity sits at roughly 0.09 to 0.11 W/(m·K), per data referenced by ThermalFinn, one of the lowest of any structural wood species. In practical terms, bench surfaces stay comfortable to the touch even at 90°C (194°F).

Cedar's heartwood decay resistance comes from those same natural oils, not from any applied chemical treatment. This is why cedar has become the standard for outdoor barrel saunas and exterior cladding. One distinction worth noting: Western red cedar is darker, more aromatic, and significantly more decay-resistant than Eastern white cedar. U.S. shoppers will encounter both when comparing specific models, so it pays to check which species a manufacturer uses.

Cost runs approximately $4 to $8 per square foot for sauna-grade lumber, making it the premium-priced option among the three. Interior maintenance is minimal. Exterior surfaces benefit from a UV-protective oil to preserve color and slow natural weathering. Light sanding may be needed periodically as oils migrate to the surface.

For eco-conscious buyers, FSC-certified Western red cedar is widely available. According to Business Research Insights, 49% of newly introduced sauna cabins in 2024 utilized certified wood materials, reflecting a strong sustainability trend across the industry.

Canadian Hemlock: The Clean, Modern Interior Wood

Canadian hemlock has a pale, creamy tone with fine, uniform grain. Unlike cedar, it stays relatively consistent in color over time, which makes it a natural fit for minimalist and modern spa aesthetics. If you have seen a sleek infrared cabin with clean lines and a light interior, there is a strong chance it was built with hemlock.

One of hemlock's most practical advantages is that it is nearly scent-free. For buyers with fragrance sensitivity, or anyone spending extended time in an enclosed infrared cabin, this matters. As awareness of indoor air quality and VOC exposure grows, hemlock's near-zero aromatic compound profile has become a genuine selling point rather than a neutral characteristic.

Hemlock also has very low resin content, meaning no sticky sap or irritating fumes under high heat. This is a key advantage over pine and some other softwoods, and it is one of the primary reasons hemlock dominates infrared sauna interiors in North America, as noted by Sauna Supply Co.

Dimensional stability is another strength. Hemlock holds its shape well through repeated heat cycling, contributing to tight, consistent joinery in cabin-style builds. Cost typically runs $3 to $6 per square foot, roughly 20 to 40% less per board foot than Western red cedar, according to Peak Primal Wellness.

One important limitation: hemlock is not recommended for exposed outdoor cladding in cold climates. LeisureCraft, a manufacturer of SaunaLife and LeisureCraft products, explicitly advises against using hemlock, spruce, or pine as exterior cladding in these conditions, recommending cedar instead.

Care is straightforward. Hemlock is the lowest-maintenance of the three species for interior use. Routine cleaning with a soft brush or mild sauna cleaner is generally sufficient; no oiling is required. A notable 2026 design trend: hemlock is being repositioned from "budget default" to "modern spa minimal" as premium buyers increasingly treat wood species as a design identity decision rather than a cost consideration.

Nordic Spruce: The Traditional Finnish Choice

Nordic (Norway) spruce is the most widely used sauna wood in Finland, the birthplace of sauna culture. It appears in the vast majority of Finnish sauna builds, primarily for wall and ceiling cladding, according to Sauna Supply Co. and Finnmark Sauna. Its light, almost white tone aligns well with the growing trend toward minimalist, light-wood Scandinavian sauna interiors.

An important nuance that many basic comparisons skip: in traditional Finnish builds, spruce is used for walls and ceilings, while softer, lower-conductivity woods like aspen or abachi are used for skin-contact bench surfaces. If you are evaluating a barrel sauna or kit that specifies spruce throughout, it is worth understanding this distinction and asking what the bench material is.

Spruce contains natural resin that can vary from board to board. Grade matters here. Look for Grade AB or European Grade A with small, tight knots. Lower grades may bleed sap under sustained high heat, which is both a cosmetic and practical concern.

Cost is the lowest of the three species, running approximately $2 to $4 per square foot for sauna-grade lumber, per Tahoe Sauna Company.

Thermowood (thermally modified spruce) deserves special attention. The thermal modification process removes natural resins and significantly improves moisture resistance and dimensional stability. This makes thermowood spruce a viable premium option for both indoor and outdoor builds, effectively bridging spruce's affordability and Nordic authenticity with cedar's weather performance. This is an emerging category that most basic cedar-vs-hemlock articles overlook entirely.

For outdoor use, untreated spruce requires a protective coating or paraffin oil treatment. Thermowood spruce is a considerably stronger outdoor candidate. Over time, untreated spruce develops a silver patina outdoors, a natural look some buyers appreciate while others prefer to prevent with periodic oiling. Nordic spruce is sustainably harvested from Finnish and Baltic forests, with strong FSC availability.

Cedar vs Hemlock vs Spruce: Quick Comparison Table

Feature	Western Red Cedar	Canadian Hemlock	Nordic Spruce
Color	Reddish-brown, darkens over time	Pale, creamy, stays uniform	Light, almost white
Aroma	Distinctive cedar scent	Nearly scent-free	Mild, subtle wood scent
Thermal Conductivity	~0.09–0.11 W/(m·K)	Low (comfortable bench feel)	Moderate (bench wood often swapped)
Typical Use	Outdoor barrel & cabin saunas	Indoor infrared cabins	Traditional Finnish walls & ceilings
Cost (per sq ft)	$4–$8	$3–$6	$2–$4
Maintenance	Low (UV oil for exterior)	Minimal (routine cleaning)	Moderate (paraffin oil recommended)
Outdoor Suitability	Excellent (natural decay resistance)	Not recommended for cladding	Requires treatment; thermowood is viable

No single species wins across every category. Each wood excels in its natural context, and the right choice depends on your sauna type, location, and preferences.

How to Choose: Match Wood to Your Sauna Setup

The most practical starting point is your installation context: are you building an indoor infrared cabin, or placing a traditional or barrel sauna outdoors? This single factor narrows the field more than any other.

Outdoor sauna or barrel sauna: Cedar is the clear standard for exterior cladding due to its natural decay resistance. Thermowood spruce is a viable premium alternative. Hemlock is not recommended for exposed outdoor cladding in cold climates, per LeisureCraft's manufacturer guidance. To see cedar construction in practice, browse the Outdoor Saunas collection, which includes cedar barrel and cabin models like the SaunaLife Model E8W, Model G3, GL4, CL5G, and G11.

Indoor infrared cabin: Hemlock is the dominant choice for good reason. It is scent-free, dimensionally stable, cost-effective, and well-suited to extended low-temperature sessions in enclosed spaces.

Traditional Finnish-style indoor sauna: Spruce for walls and ceilings is authentic and affordable. Pair it with aspen or abachi benches for skin-contact surfaces.

Budget: Spruce ($2 to $4 per square foot) suits buyers prioritizing Nordic authenticity at lower cost. Hemlock ($3 to $6) balances quality and value. Cedar ($4 to $8) is the premium choice with the longest outdoor track record.

Scent sensitivity: Buyers with fragrance sensitivity or respiratory considerations should strongly consider hemlock for its near-zero aromatic compound profile.

Design identity: Cedar signals warm luxury. Spruce signals Nordic minimalism. Hemlock signals clean modern spa. Choose the aesthetic that fits your space and personal style.

Caring for Your Sauna Wood Over Time

Cedar interior: Light sanding periodically as natural oils migrate to the surface. Exterior cedar benefits from UV-protective oil to preserve color and slow weathering.

Hemlock interior: Minimal maintenance. Routine cleaning with a soft brush or mild sauna cleaner is generally sufficient. No oiling required.

Spruce interior: Paraffin oil treatment is recommended to reduce resin bleed and improve moisture resistance, especially in high-heat traditional sauna environments.

Spruce exterior (untreated): Requires protective coating or oil to prevent weathering. Thermowood spruce requires less maintenance than untreated spruce outdoors.

All species: Avoid harsh chemical cleaners. Allow adequate ventilation after each session to prevent moisture buildup. Inspect joinery annually for any movement.

Aging is natural and expected. Cedar darkens and develops a warm patina. Hemlock stays relatively uniform. Untreated spruce silvers outdoors. Setting these expectations early means you will not be surprised by changes that are simply the wood behaving as wood does.

Frequently Asked Questions About Sauna Wood Types

Is cedar or hemlock better for a sauna?

It depends on the use case. Cedar is the stronger choice for outdoor saunas where decay resistance and aroma are valued. Hemlock is better suited to indoor infrared cabins where a scent-free, stable, and cost-effective interior matters most.

Can spruce be used for sauna benches?

Traditionally, spruce is used for walls and ceilings in Finnish saunas. Softer woods like aspen or abachi are preferred for bench surfaces due to their lower thermal conductivity, which keeps them more comfortable against bare skin at high temperatures.

What is thermowood, and is it worth it?

Thermowood is thermally modified spruce. The process removes natural resins and significantly improves moisture resistance and dimensional stability. It is a premium option that bridges spruce's affordability with cedar's weather performance, making it worth considering for outdoor builds or buyers who want spruce's aesthetic with better durability.

Does sauna wood need to be sealed or treated?

Interior sauna wood should generally not be sealed with varnish or paint, as these coatings trap heat and can release fumes. Specific treatments are appropriate in certain cases: paraffin oil for spruce interiors to reduce resin bleed, and UV-protective oil for exterior cedar surfaces to slow weathering.

Is FSC-certified sauna wood available?

Yes. Western red cedar, Canadian hemlock, and Nordic spruce are all available with FSC certification. As noted earlier, 49% of new sauna cabins introduced in 2024 used certified wood materials, reflecting strong industry momentum toward sustainable sourcing.

The Right Wood for Your Sauna Starts With the Right Questions

Cedar, hemlock, and spruce are each the right choice in the right context. The goal is not to find a universal winner but to match wood to your specific sauna style, location, and preferences.

A quick recap: outdoor or barrel sauna builds favor cedar for its natural durability. Indoor infrared cabins pair best with hemlock's scent-free stability. Traditional Finnish-style saunas use spruce for walls and ceilings, with appropriate bench wood for skin-contact surfaces.

If you want to see how these materials come together in finished saunas, browse the outdoor collection or reach out to Sauna Luxuries directly. We source directly from authorized manufacturer channels, and every wood species claim about our products is verified against current product pages and manufacturer documentation. Our goal is to help you make a confident, well-informed decision rather than push a single answer.

Compare models online, or contact us with questions about wood species, construction details, or fit for your specific space. We are here to help.

This article was written with input from sauna construction specialists and cross-referenced against manufacturer documentation.

Sources

• Western Red Cedar Lumber Association (Real Cedar)
• ThermalFinn — Sauna Wood Thermal Conductivity
• Business Research Insights — Sauna Industry Sustainability Data
• Sauna Supply Co. — Canadian Hemlock
• Peak Primal Wellness — Hemlock Wood for Sauna
• LeisureCraft — Cedar vs Hemlock vs Thermowood Guide
• Sauna Supply Co. — Why Nordic Spruce
• Finnmark Sauna — Choosing the Right Timber
• Tahoe Sauna Company — Best Wood for Sauna