Best Wood for a Sauna: Cedar, Hemlock, Redwood and More
What wood are saunas made of?
Sauna wood has to survive a harsh cycle: room temperature to 150-195°F (66-91°C) in a traditional sauna, bursts of humidity from steam, then cooling again, sometimes several times a day. The wood also touches bare skin. That leads to a short list of requirements:
- Low density, so surfaces conduct heat slowly and stay comfortable to touch
- Dimensional stability, so boards do not cup, crack or open gaps as they heat and cool
- Low resin and few knots on anything people sit on or lean against
- Decay resistance for outdoor saunas and humid rooms
- Untreated, kiln-dried stock, with no paints, varnishes or pressure treatment inside the hot room
The species that meet those requirements are almost all softwoods: western red cedar, hemlock, redwood, spruce, pine and aspen (technically a hardwood, but a very light one), plus thermally modified versions of several of them.
How do the main sauna woods compare?
| Property | Western red cedar | Western hemlock | Redwood | Aspen | Norway spruce | Pine (Scots) |
|---|---|---|---|---|---|---|
| Dried density | ~380 kg/m³ | ~465 kg/m³ | ~415 kg/m³ | ~415 kg/m³ | ~405 kg/m³ | ~545 kg/m³ |
| Heartwood decay resistance | Very durable | Not durable | Moderately to very durable | Non-durable | Slightly to non-resistant | Moderate |
| Aroma | Strong cedar scent | Mild, near neutral | Mild; fades after machining | None | None to very slight | Mild resin |
| Color | Reddish to brown, varied | Pale, uniform | Reddish brown | Pale, near white | Pale cream | Pale yellow, knots |
| Typical knots and resin | Low in clear grades | Low | Low in clear grades | Very low | Moderate | Higher |
| Best fit | Outdoor and premium indoor | Indoor infrared and traditional | Premium indoor and outdoor | Benches, interiors, aroma-sensitive users | Nordic-style interiors | Budget interiors |
Values for cedar, hemlock and pine are from ForestSource species pages for western red cedar, western hemlock and Scots pine; redwood, aspen and spruce are from The Wood Database pages for redwood, quaking aspen and Norway spruce. The two sources measure slightly differently, and real lumber varies by origin, grade and moisture content, so treat these as reference values.
Why is western red cedar the benchmark sauna wood?
Three properties make cedar the default premium specification:
- Low density. Real Cedar lists an oven-dry density of about 21 pcf (specific gravity 0.32). Lower-density wood conducts heat more slowly, so surfaces feel comfortable, and panels are lighter to ship and handle.
- Stability. The same source describes cedar's shrinkage as very low: kiln-dried stock shrinks only about 0.3% radially and 0.7% tangentially from 15% to 12% moisture content. That matters in a room that heats and cools every session.
- Natural durability. Cedar heartwood is rated very durable against decay fungi, which is why it dominates outdoor barrel and cube saunas.
Real Cedar also lists a thermal conductivity of 0.74 BTU·in/(ft²·h·°F) at 12% moisture content and a Class B flame spread rating of 45, useful figures when dealers ask about insulation or interior finish codes.
The trade-offs: cedar costs more, color varies board to board, and its aroma is strong. Some users love the scent; others prefer a neutral wood. Western red cedar sauna wood is usually sold as tongue and groove paneling for walls and ceilings and as clear-grade boards for benches. Browse red cedar saunas.
Hemlock vs cedar sauna: which should you choose?
Hemlock is the practical choice for many indoor saunas, particularly infrared cabins where air temperatures stay lower. Its strengths are a clean, uniform appearance, mild odor and consistent supply at a lower cost than cedar. It is also a good answer for customers sensitive to strong aromas.
Its weakness is outdoor durability. ForestSource rates hemlock heartwood as not durable against decay fungi and describes it as best for interior applications. Do not specify untreated hemlock for exterior walls, roofs or barrel staves.
| Question | Choose cedar | Choose hemlock |
|---|---|---|
| Outdoors? | Yes | No, unless fully protected |
| Want a cedar scent? | Yes | No, prefer neutral |
| Traditional high-heat room? | Preferred | Acceptable indoors |
| Infrared cabin on a budget? | Optional upgrade | Strong value choice |
| Uniform pale look? | No, color varies | Yes |
Many suppliers offer the same cabin in both woods at different price points. See hemlock saunas for indoor models.
Is a redwood sauna a good idea?
Redwood is a strong sauna wood. The Wood Database lists an average dried weight of about 26 lb/ft³ (415 kg/m³), a Janka hardness of 450 lbf, and heartwood rated moderately to very durable, with old-growth more durable than second-growth. It has a distinct smell when worked, but unlike cedar the odor fades afterward.
That makes redwood suitable for premium indoor rooms and for outdoor builds such as a redwood barrel sauna. The main constraints are supply and cost: redwood is a North American species, and availability of clear, durable heartwood varies. When comparing redwood sauna kits with cedar ones, ask for heartwood content, grade and whether lumber is old-growth or second-growth.
Aspen sauna wood: why is it popular for benches?
Aspen is pale, soft, almost knot-free and has no characteristic odor, with a Janka hardness of only 350 lbf. Those traits make it comfortable to sit on and ideal for people who want no wood scent at all, which is why aspen is a common choice for sauna benches and interiors in Scandinavia.
Its limitation is durability: the same source rates aspen as non-durable and susceptible to insects, so keep it indoors and ventilate well.
Thermo aspen is aspen that has been thermally modified: heated above 180°C in a low-oxygen process. According to the thermally modified wood overview, this reduces shrinking and swelling by roughly 50-90% and improves resistance to some decay organisms, at the cost of up to 30% lower bending strength. Sauna materials were one of the first markets for thermally modified timber. Thermo wood is darker, very stable and works well for benches and feature walls.
Spruce and pine for saunas: when do they make sense?
Spruce and pine are the traditional materials of many Nordic saunas and the most affordable options.
- Spruce sauna wood, including Nordic or Norway spruce, is pale, light (about 405 kg/m³) and nearly odorless. It is a good value choice for wall paneling in indoor rooms, though its decay resistance is low.
- Pine for sauna use is denser (Scots pine around 545 kg/m³) and usually has more knots and resin. Resin pockets can weep under heat, leaving sticky spots, and knots are denser than the surrounding wood, so they can feel hot on benches and backrests.
If you use pine or spruce, specify clear or select grades for anything people touch, confirm kiln-drying, and consider a different species for benches.
What is the best wood for sauna walls, benches and interiors?
Walls, ceilings and benches do not need to use the same species. Benches and backrests have constant skin contact, so they need the softest, clearest and lowest-resin wood. Walls and ceilings can use a more economical species or grade.
| Application | Recommended woods | Why |
|---|---|---|
| Outdoor barrel or cube sauna | Western red cedar heartwood, redwood heartwood, thermally modified wood | Decay resistance, stability |
| Traditional indoor sauna, premium | Western red cedar, redwood | Stability under high heat, comfort |
| Indoor infrared sauna, mid-range | Hemlock | Neutral odor, uniform look, value |
| Benches and backrests | Clear cedar, aspen, thermo aspen, clear hemlock | Soft, knot-free, low resin |
| Nordic-style interior, budget | Spruce or clear pine | Low cost, pale look |
| Aroma-sensitive users | Hemlock, aspen, spruce | Little or no scent |
The best wood for infrared sauna cabins is often hemlock or cedar, since lower air temperatures put less stress on the timber. For outdoor builds, read the barrel sauna guide; for framing, insulation and paneling, see how to build a sauna.
Sauna lumber and paneling checklist
Use this when buying sauna boards, planks or prefab cabins:
- Species named precisely (for example western red cedar, Thuja plicata; western hemlock, Tsuga heterophylla)
- Heartwood content for outdoor parts
- Grade per component: clear, select or knotty
- Kiln-dried moisture content target and tolerance
- Profile: tongue and groove for walls and ceilings, with thickness stated
- Bench board thickness and edge profile, with hidden fasteners
- No paints, varnishes, pressure treatment or adhesive-heavy panels inside the hot room
- Exterior finish system specified for outdoor units
- A photographed sample panel approved as the quality reference
- Timber legality documentation if your market requires it
What woods does Mars Sauna use?
Mars Sauna builds cabins in Canadian hemlock and western red cedar, and OEM and ODM buyers can customize wood species and grade along with size, heater layout, voltage, control panel, logo and packaging. See custom OEM saunas.
Key takeaways
- The best wood for a sauna is light, stable and low in resin; western red cedar (about 380 kg/m³) is the benchmark, especially outdoors.
- Hemlock is the value choice for indoor and infrared saunas, with a pale look and mild scent, but should not be used untreated outdoors.
- Redwood is a durable premium alternative; aspen and thermo aspen excel on benches; spruce and clear pine suit budget Nordic interiors.
- Specify species, grade and moisture content per component, not just "cedar sauna".
- Never use treated, painted or adhesive-heavy materials inside the hot room.
Need cedar and hemlock samples or a quote? Contact our export team.
Frequently asked questions
What is the best wood for a sauna?
Western red cedar is widely considered the best all-round sauna wood because it is light, very stable under heat and its heartwood resists decay, which also makes it the default for outdoor saunas. Hemlock, aspen and spruce are excellent indoor alternatives with milder scent, and redwood is a durable premium option in North America.
Is hemlock or cedar better for a sauna?
Cedar is better outdoors and in premium high-heat rooms because it is lighter, more stable and naturally decay resistant. Hemlock is often the better value indoors, especially for infrared cabins: it is pale, uniform, nearly odorless and usually less expensive. Untreated hemlock should not be used for exterior walls or barrel staves.
Is redwood good for a sauna?
Yes. Redwood is light (about 415 kg/m³ dried), soft, stable and its heartwood is rated moderately to very durable, so it works indoors and outdoors, including in barrel saunas. Its scent is milder than cedar and fades after machining. Supply is mainly North American and second-growth lumber is less durable than old-growth.
What wood is used in Finnish saunas?
Traditional Finnish and Nordic saunas commonly use local spruce and pine for walls and ceilings, with aspen, alder or thermally modified wood for benches. These species are pale, low in odor and readily available in Scandinavia. Western red cedar is more common in North American saunas.
What is the best wood for sauna benches?
The best sauna bench wood is low in density, knot-free and low in resin so it stays comfortable to touch. Clear-grade western red cedar, aspen, hemlock and thermally modified aspen are popular choices. Avoid knotty pine on benches, because resin can weep and dense knots can feel hot.
Can you use pine for a sauna?
Yes, pine is widely used in Nordic saunas and is the most affordable option, but it is denser than cedar and usually has more knots and resin. Under heat, resin pockets can weep and knots can get hot. Specify clear, kiln-dried grades for anything people touch, and consider a different species for benches.
What wood should not be used in a sauna?
Avoid pressure-treated lumber, painted or varnished boards, plywood and composite panels with adhesives that can off-gas under heat, and very dense or resinous woods on contact surfaces. Hardwoods such as oak conduct heat faster and can feel uncomfortably hot. Use untreated, kiln-dried softwood or thermally modified wood indoors.
