Sauna Bench Wood

Bench wood is the single most important material choice in your sauna — it's the surface you sit on with bare skin at 170°F+. The wrong wood species can cause burns, splinters, resin bleeding, or uncomfortable heat retention. The right species stays cool to the touch, resists splintering, won't secrete sap, and feels smooth against skin even after years of use. Every board in this collection is specifically graded and milled for bench use: sanded smooth, free of loose knots, and cut to dimensions designed for bench construction.

Not sure how much wood you need? Use our Sauna Wood Calculator to estimate bench board quantities based on your bench dimensions. For help choosing the right species, read our guide to the best sauna wood types or our complete bench-building guide.

Bench Board Sizes: 1" vs. 5/4" Thickness

Bench boards are available in two thicknesses: nominal 1" (actual ~3/4") and nominal 5/4" (actual ~1"). The 1" boards are lighter and work well for bench surfaces that are fully supported by framing underneath. The 5/4" boards are thicker and sturdier — they span wider gaps between support framing without flexing, and they feel more substantial underfoot if used for a stepping platform. Most builders use 5/4" boards for the primary seating surface and 1" boards for lighter applications like lower bench tiers or backrests. Width options range from 3" to 6" depending on the species.

Bench Wood by Species

Thermo-Aspen — Our best-selling bench wood by a wide margin. Thermally modified aspen has an attractive golden-brown color, stays exceptionally cool to the touch (low thermal conductivity), won't secrete resin, and doesn't splinter. The thermal modification process makes it more dimensionally stable than untreated aspen, so boards resist warping and cupping through repeated heat cycling. Available from ProSaunas in five sizes: 1×3, 1×4, 5/4×3, 5/4×4, and 5/4×6. This is the widest bench size selection of any species we carry, making it easy to achieve the exact bench look you want — narrower boards for a traditional slatted appearance, wider boards for a more modern, continuous surface.

Aspen (Natural) — Untreated aspen is a light, creamy-white wood with a subtle grain and soft texture. Like thermo-aspen, it stays cool against skin and doesn't produce resin. The lighter color creates a bright, clean sauna interior — a different aesthetic than the golden-brown of thermal modification. Available from ProSaunas as 1×4 bench boards. Natural aspen is the most affordable bench option and works well for saunas where you prefer a lighter, Scandinavian look.

Alder — Alder has a fine, uniform grain and a warm pinkish-brown tone that darkens slightly with age. It's a traditional Finnish sauna wood prized for its smooth surface, low heat conductivity, and workability. Available from ProSaunas in 5/4×4 and 5/4×6. Alder bench boards pair naturally with alder wall cladding for a cohesive interior, though mixing alder benches with a different wall species (like thermo-aspen or cedar) is a popular two-tone approach.

Western Red Cedar — The classic North American sauna wood. Cedar bench boards have a distinctive reddish-brown color and the signature aromatic scent that many sauna enthusiasts associate with the traditional sauna experience. Naturally resistant to rot and decay. Available from ProSaunas as 2×4 vertical grain, clear grade A+ bench material — the thickest, most premium bench board we carry. Cedar is the most expensive bench option per linear foot but delivers unmatched visual character and fragrance.

Thermo-Spruce — Thermally modified spruce has a golden-brown color similar to thermo-aspen but with a coarser, more rustic grain texture. It provides excellent thermal insulation and a traditional Nordic look. Available from ProSaunas as 5/4×4 bench boards. The thermo-spruce bench lineup is limited to one size, so for projects requiring multiple bench board widths, consider pairing thermo-spruce walls with thermo-aspen bench material (both are golden-brown thermowoods that complement each other visually).

Thermo-Alder — Thermally modified alder from Thermory in a rich warm brown. Sold as board packs (1×4 five-board pack or 5/4×4 four-board pack) rather than individual boards. Thermory also offers prebuilt bench modules — ready-to-install 63" and 94.5" bench sections, a corner piece, and an 81" backrest — which are the fastest path to a finished bench system without any custom cutting or assembly. A black wax finish option is available for accent surfaces.

Why Bench Wood Is Different from Wall Cladding

Bench boards and wall cladding are milled differently because they serve different purposes. Wall cladding has tongue-and-groove profiles that interlock for a tight, gapless surface — great for walls and ceilings, but those interlocking edges would trap moisture and prevent air circulation on a bench surface. Bench boards are flat-sawn with square or slightly rounded edges, designed to be installed with small gaps between boards. Those gaps allow air to circulate around the bench structure, promoting drying between sessions and preventing moisture buildup that leads to rot. Bench boards are also sanded to a smoother finish than wall cladding since they're in direct contact with bare skin.

Frequently Asked Questions

What is the best wood for sauna benches?

Thermo-aspen is our top recommendation and best seller. It has the ideal combination of low heat conductivity (stays cool against skin), dimensional stability (won't warp or cup), zero resin secretion, splinter resistance, and attractive appearance. If you prefer a lighter color, natural aspen is excellent. If you want fragrance, cedar is the traditional choice. All species in this collection are suitable for sauna bench use — the "best" comes down to your aesthetic preference and budget.

How do I calculate how many boards I need?

Measure the total bench surface area (length × depth for each tier), then divide by the board width to get the number of boards per row. Add approximately 10% for waste and cuts. Our Sauna Wood Calculator handles this math for you — just enter your bench dimensions and it provides a board count. Remember to account for small gaps (typically 1/4" to 3/8") between boards for air circulation.

Do I need to seal or finish bench wood?

Thermally modified woods (thermo-aspen, thermo-spruce, thermo-alder) do not require any sealing or finish — the thermal modification process makes them naturally resistant to moisture and decay. Natural aspen, alder, and cedar can be left untreated or finished with a sauna-rated wood oil designed for high-heat environments. Never use standard polyurethane, varnish, or paint on sauna benches — these products off-gas toxic fumes at sauna temperatures. For more detail, see our wood finishing guide.

Can I mix bench wood species with a different wall species?

Absolutely — mixing species is one of the best ways to create visual contrast in a sauna interior. Popular combinations include thermo-aspen or alder benches with cedar walls (warm brown benches against reddish aromatic walls), or thermo-alder benches with thermo-aspen walls (rich brown seating against a lighter golden background). As long as both species are appropriate for sauna use, any combination works.

What bench height and depth should I build?

Standard Finnish sauna bench dimensions are 18–20" deep for the seating surface, with the upper bench 42–44" from the floor and the lower bench at 18–20" height. Our bench height and ceiling guide covers all the dimensional details, including how ceiling height, heater placement, and number of tiers affect your bench layout.

Shop more: Wood for Walls & Ceilings · Trim & Molding · All Sauna Wood · Prebuilt Benches · Backrests · Wood Oil & Finish · Bench Building Guide · Wood Calculator