Best Wood for a Sauna: Cedar vs Hemlock vs Spruce vs Aspen

The wood inside a sauna is what you lean on, sit on and breathe around at high heat, so it matters more than almost any other choice in a build. This guide compares the woods used in the saunas we sell (Canadian hemlock, western red cedar, spruce, aspen, alder and thermally modified wood) and says where each one works best.

Quick comparison

Wood	Smell	Strengths	Best for	In our range
Canadian hemlock	Mild	Smooth, knot-free finish; resists warping	Infrared and indoor sauna rooms	43 hemlock saunas
Western red cedar	Strong, distinct scent when heated	Heartwood is rated resistant to very resistant to decay; light weight	Outdoor saunas, barrels, high-end rooms	16 cedar saunas
Spruce	Light	Low sap, tight grain, budget friendly; has knots	Wall cladding and framing, traditional Finnish saunas	A few models
Aspen	None you can detect	Resin-free, stays cool to the touch	Benches and backrests	A few models
Alder	Almost none	No resin or splinters, smooth	Benches and interior cladding	Benches and accessories
Thermally modified wood	Varies	Heat treatment removes resin and improves moisture resistance and stability	Benches, floors and exterior cladding	ThermoWood cabins

Canadian hemlock

Hemlock is the most common wood in our range, used in 43 saunas, most of them infrared sauna rooms. Finnmark Sauna describes it as a durable softwood with a smooth, knot-free finish that resists warping and stays comfortable to touch. Its mild smell suits people who want a sauna that smells of very little. Hemlock rooms are often the best-priced way into a wooden infrared sauna.

Western red cedar

Cedar is the classic premium sauna wood. Virginia Tech's wood identification sheet rates western red cedar heartwood as resistant to very resistant to decay and describes the wood as light and moderately soft. Finnmark Sauna adds that it releases a distinct scent when heated and is naturally resistant to moisture, rot and insects, which is why it is popular for outdoor saunas and barrel saunas. The trade-off is price, and the strong aroma, which some people love and others find too much.

Spruce

Spruce is a traditional Nordic sauna wood and a budget-friendly choice. Finnmark Sauna notes its low sap content and tight grain, but because it has natural knots it is recommended for wall cladding and framing rather than benches, where a hot knot can be uncomfortable against bare skin.

Aspen and alder

These are the bench woods. Aspen has no detectable aroma, is resin-free and stays cool to the touch even at high temperatures, according to Finnmark Sauna. Alder is almost scent-free and does not release resin or splinters. Both are good picks for anyone sensitive to smells, and for any surface you sit or lean on. See sauna benches and headrests and backrests.

Thermally modified wood

Thermally modified woods such as thermo aspen, thermo spruce and ThermoWood are heated in a controlled process that removes resin and makes the wood more resistant to moisture and warping. That makes them a strong choice for benches, floors and outdoor cladding, at a higher price.

Woods to avoid

Finnmark Sauna says hardwoods such as oak and teak are rarely used in saunas because they conduct heat too well and get uncomfortably hot. Avoid treated, painted or varnished lumber inside the hot room.

How to choose

• Infrared room on a budget: hemlock.
• Outdoor or barrel sauna: red cedar or thermally modified wood.
• Traditional Finnish feel: spruce walls with aspen or alder benches.
• Sensitive to smells: aspen, alder or hemlock rather than cedar.

Next, size your heater with our sauna heater size calculator, or compare far infrared saunas and traditional saunas.

Sources: Finnmark Sauna, choosing the right timber for your sauna; Virginia Tech, western redcedar wood identification.