Sauna Wood: Best Species for Every Part of the Build

Updated January 2025 — Backyard Sauna Pro

Sauna wood selection matters more than most people think. The wrong species leads to warping, dripping resin, splinters, or uncomfortable bench temperatures. Here is the definitive breakdown by application.

Best Wood by Sauna Application

Benches

Bench wood needs to stay cool to the touch, resist splintering, and handle constant moisture exposure. The best options:

• Aspen: The Finnish standard. Low density, low resin, stays cool at sauna temperatures, very light color. The most common bench wood in Scandinavian saunas.
• Abachi (African whitewood): Very low thermal conductivity — stays noticeably cooler than cedar on the bench surface. Used in many European premium saunas. White color, smooth grain.
• Western red cedar: Popular in North America, pleasant scent, naturally moisture-resistant. Slightly higher thermal conductivity than aspen but comfortable for most users. Widely available.
• Nordic spruce: Traditional in Finland, good moisture resistance, neutral scent. Can develop minor checking over time but holds up well with proper ventilation.

Avoid bench surfaces made from pine (resin bleeds at heat, can cause burns), mahogany or tropical hardwoods (retain too much surface heat), or any treated/stained lumber.

Wall Paneling and Ceiling

Same considerations as benches but with slightly more flexibility since you are not in direct contact. Cedar and spruce are the most common. Standard tongue-and-groove paneling in 1x4 or 1x6 profile works well. The gap between boards allows expansion and contraction with humidity changes without buckling.

Ceiling paneling sees the most heat and humidity — use the same species as the bench for consistency. Thinner boards (5/8" to 3/4") work better than thick planks on the ceiling because they flex more and are less prone to checking.

Framing

Standard kiln-dried 2x4 or 2x6 construction lumber is fine for framing. The framing is behind the vapor barrier and paneling — it does not need to be the same species as the finish surfaces. Do not use pressure-treated lumber anywhere inside the sauna envelope; the chemicals used in treatment off-gas at sauna temperatures.

For outdoor saunas on a raised foundation, pressure-treated lumber is appropriate for floor framing below the vapor barrier layer where it contacts the ground or is exposed to weather.

Exterior

Cedar or redwood for exterior siding — both resist rot and weather naturally without treatment. Many barrel saunas are left with raw cedar exterior that weathers to silver-gray over time. For painted or stained exteriors, use standard exterior grade cedar or spruce and finish it with a quality exterior stain.

Species Comparison

Cedar vs Hemlock

Cedar costs 20-40% more than hemlock. Both work well for sauna interiors. Cedar has a stronger natural scent that many people enjoy; hemlock is more neutral. Cedar resists moisture slightly better over time. For most buyers on a budget, hemlock is a perfectly solid choice. See our full cedar vs hemlock comparison for the detailed breakdown.

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