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Building or renovating a custom sauna starts with choosing the right wood. We carry tongue-and-groove wall cladding, bench material, and molding trim from ProSaunas in nine sauna-grade wood species — everything you need to line your sauna room from floor to ceiling. All wood is kiln-dried, pre-sanded, and specifically graded for sauna environments. Free shipping on every order.
Not sure how much wood you need? Our Sauna Wood Calculator estimates the exact square footage and board count for your project based on your room dimensions. Need help choosing a species or planning your build? Call or text us at (360) 233-2867 or use our Custom Sauna Design & Materials Quote Service.
Wall & Ceiling Cladding — Tongue-and-groove boards for lining sauna walls and ceilings. Available in V-gap, nickel gap, and medium gap profiles depending on the species. Profile choice is primarily aesthetic — V-gap is the classic look, nickel gap is the modern standard, and medium gap creates a more pronounced shadow line for a contemporary feel.
Bench Material — Thicker boards in 1×3", 1×4", 5/4×3", 5/4×4", 5/4×6", and 2×4" profiles for building sauna benches. Bench wood needs to be smooth, splinter-free, and a species that stays cool to the touch at sauna temperatures — all of our bench stock meets these requirements. Low-density species like aspen, thermo-aspen, and alder are the most popular choices for benches since they don't get as hot as denser woods.
Molding & Trim — Inside corner molding, right angle molding, flat trim, and other profiles for finishing corners, edges, door frames, and transitions between cladding boards. Matching species keep your sauna looking clean and cohesive.
Thermo-Aspen — Our most popular sauna wood. Thermally modified aspen has a warm brown tone, excellent dimensional stability, and very low thermal conductivity (stays cool to the touch). The thermal modification process reduces moisture absorption by up to 50% compared to untreated wood, meaning less swelling, shrinking, and warping in the humid sauna environment. Thermo-aspen is the go-to species for modern Scandinavian and European-style saunas. Available in wall cladding, bench stock, and trim.
Aspen — Untreated aspen with a light, neutral tone and smooth grain. Naturally low-density so it stays cool on benches. A good choice if you prefer a lighter, more natural look compared to the brown tones of thermo-aspen. Also the most affordable option in the lineup.
Alder (Black Alder) — A European hardwood with a calm beige tone and pleasant fine texture. Alder is moisture-resistant, doesn't overheat, and has a subtle, understated look that works well in both modern and traditional designs. Popular in European sauna builds and pairs perfectly with alder-framed sauna doors.
Thermo-Alder — Thermally modified version of alder with a deeper brown tone and the same enhanced stability and moisture resistance that thermal modification provides. A premium option for builders who want the alder grain pattern with better long-term performance in high-humidity conditions.
Western Red Cedar — The traditional North American sauna wood. Cedar is naturally decay-resistant, insect-resistant, and aromatic — that classic sauna smell comes from the wood. It has a rich reddish-brown color with natural variation that many people find beautiful. Cedar has been the default choice in North American saunas for decades and remains popular, particularly for outdoor builds where natural rot resistance matters. Available in wall cladding, bench stock, and trim from ProSaunas in clear grade A+ vertical grain.
Thermo-Spruce — Thermally modified spruce with an attractive golden-brown color. Spruce doesn't secrete resin, splinter, or overheat, making it an ideal sauna material. The thermal treatment gives it enhanced durability and moisture resistance. A good mid-range option that's popular in European sauna builds.
Thermo-Radiata Pine — Thermally modified radiata pine with a rich, warm tone. Radiata pine takes the thermal modification process particularly well, resulting in a stable, moisture-resistant board with a distinctive grain pattern. An appealing option if you want something different from the more common aspen and alder looks.
Hemlock — A clean, light-colored softwood with minimal grain pattern. Hemlock is a traditional sauna wood in North America, widely used in commercial and residential builds. It's hypoallergenic and has almost no scent — a good choice for people sensitive to the stronger aromas of cedar.
Thermo-Magnolia — A unique option with a distinctive grain pattern and warm brown tones. Thermally modified magnolia is stable and moisture-resistant with a look that sets it apart from more common sauna species.
This is the most common question we get about sauna wood. Cedar has been the North American standard for decades — it's naturally rot-resistant, aromatic, and widely available. Thermally modified woods (thermo-aspen, thermo-spruce, thermo-alder, etc.) are the European standard and have been gaining ground rapidly in North America.
Thermally modified wood goes through a high-heat treatment process (typically 400°F+) that permanently alters the wood's cell structure, reducing moisture absorption and dramatically improving dimensional stability. The result is wood that swells and shrinks less than untreated wood, resists rot without chemical treatment, and maintains its appearance longer in the harsh sauna environment.
There's no single "best" — it depends on your priorities. Cedar wins on natural aroma and availability. Thermowood wins on dimensional stability and moisture performance. Both are excellent sauna materials. For a detailed comparison, read our thermowood vs. cedar guide and our complete guide to sauna wood types.
Sauna wood inside the hot room is generally left unfinished — most sealants and finishes off-gas at sauna temperatures and can interfere with the wood's ability to breathe and regulate moisture. If you do want to treat your wood, use only products specifically designed for sauna interiors. We carry sauna wood oils and finishes that are safe for high-heat environments.
For a complete guide on when and how to finish sauna wood (and when to leave it alone), read our guide to finishing wood in a sauna.
Use our Sauna Wood Calculator to estimate the exact amount of cladding, bench stock, and trim you need based on your room dimensions. For a step-by-step walkthrough of the entire sauna build process — framing, insulation, vapor barrier, wood installation, heater selection, electrical, and finishing — see our A–Z Custom Sauna Room Guide.
Want us to plan it for you? Our Custom Sauna Design & Materials Quote Service provides a complete materials list and design plan for your specific project.
Thermo-aspen is our most popular choice for walls — it's dimensionally stable, stays cool, and has a clean modern look. Cedar is the traditional North American choice with natural rot resistance and a distinctive aroma. Alder and thermo-spruce are excellent European alternatives. All of these species work well for sauna walls. See our complete sauna wood guide for a detailed comparison.
Low-density species that stay cool to the touch: thermo-aspen, aspen, and alder are the top choices. Cedar also works well for benches. Avoid high-density hardwoods — they absorb and retain more heat, making them uncomfortable to sit on at sauna temperatures. Browse our bench wood selection.
Not recommended. Standard construction lumber (SPF — spruce, pine, fir) is not graded or dried for sauna conditions. It contains moisture that will cause warping, it can secrete resin at high temperatures, and it's not selected for the smooth, knot-free finish you want on sauna surfaces. Sauna-grade wood is kiln-dried to low moisture content, clear-graded (minimal knots), and pre-sanded for a smooth finish.
Use our Sauna Wood Calculator — enter your room dimensions and it calculates the exact board count for walls, ceiling, and benches. Important: tongue-and-groove boards have a coverage width that's narrower than the board width (typically about 3" of coverage per 1×4" board) because of the interlocking joint. Our calculator accounts for this.
Inside the hot room, wood is typically left natural. Sauna-specific wood oils can be applied for protection and color enhancement, but standard wood stains and polyurethanes should never be used — they off-gas at sauna temperatures. See our sauna wood finishing guide and our sauna-safe wood oils.
These refer to the shape and width of the groove between installed cladding boards. V-gap has a small V-shaped channel — the traditional look. Nickel gap has a narrow square groove — the modern, clean look (named because a nickel coin fits in the gap). Medium gap has a wider square groove for a more pronounced shadow line. The profile is a cosmetic choice and doesn't affect performance. Pick the one that matches your aesthetic.
Our Sauna Learning Center has in-depth guides on the best sauna wood types, thermowood vs. cedar, why thermowood is the best choice for saunas, and how to finish wood in a sauna. Questions? Call or text us at (360) 233-2867.
Shop by species: Thermo-Aspen · Aspen · Alder · Thermo-Alder · Cedar · Thermo-Spruce · Thermo-Radiata Pine · Hemlock · Thermo-Magnolia
Shop by use: Wall & Ceiling Cladding · Bench Material · Molding & Trim
Shop more: Sauna Wood Oil & Finish · Sauna Doors · Glass Windows & Walls · Pre-Built Benches · Sauna Lighting · All Sauna Parts
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