Cedar vs Hemlock Sauna: Which Wood Is Better?

Updated January 2025 — Backyard Sauna Pro

Cedar and hemlock are the two most common woods in prefab sauna kits. Both work well. The right choice depends on where your sauna is going, how sensitive you are to wood scent, and what you're optimizing for.

The short answer: cedar for outdoor, hemlock for indoor. Here's why.

Cedar

Why it's the outdoor default

Western red cedar contains natural terpene oils that resist moisture penetration, fungal growth, and rot. This is what makes it the standard for outdoor decks, fencing, and siding, and what makes it the right choice for barrel and cabin saunas that live outside year-round. An outdoor cedar sauna with basic annual maintenance (exterior oiling every year or two) will last 20 to 30 years.

Cedar is also dimensionally stable. It shrinks and swells less than most softwoods as humidity cycles, which matters a lot in a structure that goes from ambient outdoor humidity to 160°F+ steam and back, daily.

The smell

Cedar has a distinct aroma that intensifies with heat. Most sauna users find it pleasant, it's part of the sensory experience. A minority find it too strong or irritating, particularly people with sensitivities to natural terpenes. If you've never spent time in a cedar sauna, try one before buying. The smell is not subtle.

The aroma fades over years of use as the volatile oils dissipate. A sauna that's five years old smells less than a brand-new one.

Appearance

Cedar has a warmer reddish-brown color with visible grain variation and occasional knots. It looks rustic and natural. If you prefer a clean, uniform Scandinavian aesthetic, hemlock or aspen may suit you better.

Hemlock

Why it's the indoor default

Canadian hemlock (not the poisonous plant, hemlock the tree) is harder than cedar, with a tight, pale grain and minimal scent. It holds its shape well in the controlled indoor environment of a basement or spare room sauna. Dynamic Saunas, the most popular infrared sauna brand on Amazon, uses hemlock almost exclusively in their kits.

Hemlock doesn't have cedar's natural rot resistance, which is fine indoors where the wood isn't exposed to rain, soil contact, or prolonged moisture. Inside, the lack of natural oils isn't a disadvantage, it actually means the wood stays looking cleaner longer since it doesn't develop the surface oils that can darken cedar over time.

Surface temperature

Both cedar and hemlock stay cool enough to sit against at sauna temperatures. Hemlock is marginally lower conductivity than cedar, which means it stays very slightly cooler to the touch. The difference is minor and most people wouldn't notice it in practice.

Appearance

Hemlock is pale and consistent, it looks more like a modern Scandinavian sauna aesthetic than the rustic warmth of cedar. If you're going for a clean, spa-style interior, hemlock is the better visual match.

Other Woods Worth Knowing

Nordic spruce

The traditional Finnish choice. Tight grain, almost no smell, very light color. Used in most Finnish-built saunas. Hard to source in the US as prefab kits but common in custom builds.

Aspen

Extremely low conductivity, stays cooler to the touch than cedar or hemlock. No scent. Very light color. A good choice if you run high temperatures and want the benches and backrests to stay as cool as possible. Common in sauna accessories (backrests, headrests) even when the walls are another wood.

Alder

Common in European saunas. Warm reddish-brown tone, mild scent, good thermal properties. Less available in the US market but used in some premium kit lines.

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