Hemlock, Cedar or Thermowood: Picking Sauna Wood

Almost every sauna you'll look at is built from one of three woods. They're all legitimate choices, and the differences come down to scent, upkeep and price more than quality. Here's what separates them.

The one rule every sauna wood follows

Whatever the species, sauna wood has to be low in resin and low in conductivity. That rules out ordinary pine and spruce in their natural state — heat them to 190°F and resin pockets weep sticky sap onto whoever's sitting there. And it rules out any metal or dense hardwood where skin touches, because a surface that conducts heat well will burn you at temperatures the air around it won't.

That's why sauna benches are always a soft, light, dry wood. It's not tradition, it's physics.

Canadian hemlock

What we build with. Hemlock is a pale, straight-grained softwood that's become the workhorse of the sauna world.

• Nearly odorless. The sauna smells like hot wood and steam, not like the wood itself. If anyone in the household finds cedar overpowering — and some people genuinely do — this matters.
• Almost no resin, so nothing weeps at temperature.
• Smooth and stable, and it stays comfortable to sit on.
• Light in color, which keeps a small cabin feeling open. It darkens slowly with use.
• Good value, which is part of how we include a 9 kW heater, Wi-Fi control, lighting and a speaker at our prices.

The trade-off: hemlock isn't naturally rot-resistant the way cedar is, so the exterior wants a coat of sauna-safe sealant and a spot that drains. We cover that in the build guide, and it's a 30–50 minute job during assembly.

Western red cedar

The premium default, and the one people picture.

• That smell. The aromatic oils are the whole appeal for a lot of people. Others find it strong in a small hot room, especially early on.
• Naturally rot- and insect-resistant, thanks to the same oils. Good for exteriors, less demanding about sealant.
• Warm reddish color that weathers to grey outside unless you maintain it.
• Costs more — usually noticeably more per board foot, which shows up in the sticker price or gets recovered by skimping elsewhere, often the heater.

Worth knowing: cedar is soft and dents easily, and the scent fades over years of heat cycles. You're paying for it at its strongest on day one.

Thermowood (thermally modified)

Usually pine or spruce baked at high temperature in a low-oxygen kiln, which changes the wood itself.

• The resin is cooked out, which is what makes ordinary pine usable in a sauna at all.
• Very dimensionally stable — it moves less with humidity swings than untreated wood.
• Darker, caramel-brown color that people either love or don't.
• More brittle. The process costs some strength, so it's used more for cladding and benches than structure.

It's a genuinely good sauna material and common in Nordic builds. It's also the least familiar to American buyers, and pricing varies with who's importing it.

How to actually choose

• Love the smell of cedar? Buy cedar. Nothing else replicates it, and you'll be glad every session.
• Want neutral, or share the sauna with someone sensitive to scent? Hemlock.
• Want the most money going into the heater and the build instead of the species? Hemlock or thermowood.
• Extremely humid climate, minimal maintenance? Cedar's natural resistance earns its price.

One more thing worth more than species: how the wood is joined. Our staves interlock with a curved edge that sheds water off the outside instead of letting it sit in the joint, and the shell is pulled tight with two steel straps. A well-built hemlock sauna outlasts a poorly-built cedar one.

Ours are Canadian hemlock in three sizes. Call or text 817-440-4862 with questions.