Cedar vs Heat-Treated Hemlock for a Traditional Sauna

Cedar costs roughly 20 to 40 percent more per square foot than heat-treated hemlock but brings a stronger natural aroma and slightly better rot resistance, while heat-treated hemlock runs cooler to the touch, holds up just as well against warping in a hot, humid room, and costs noticeably less for a full interior build. Neither wood is objectively better. The right choice depends on whether the aromatic, classic-sauna scent of cedar matters to you enough to pay for it, or whether a lower material cost and a more neutral scent profile fits your build better.

How much more does cedar cost than heat-treated hemlock?

Clear, knot-free cedar generally runs 20 to 40 percent higher per square foot than heat-treated hemlock, and the gap widens further at the premium end of cedar grading. Lower cedar grades with visible knots close some of that price difference but change the finished look of the room, which matters if you’re going for a clean, uniform wall surface. On a mid-sized four-person interior build, that price difference in materials alone can add several hundred to over a thousand dollars to the total cost, before labor.

Which wood handles heat and moisture better over time?

Both species perform well in a properly ventilated sauna, which matters more for wood longevity than the species choice itself. Heat-treated hemlock goes through a kiln process that removes much of its natural moisture and resin, which reduces the risk of resin bleed at high temperatures and makes the wood dimensionally more stable as it heats and cools repeatedly. Cedar has natural oils that give it some inherent rot and insect resistance, which is part of why it’s the traditional choice for exterior barrel saunas exposed to weather, though a well-sealed hemlock exterior can hold up nearly as well with regular maintenance.

Does the aroma difference actually matter inside a hot room?

This is the most subjective part of the comparison, and it’s a real factor for a lot of buyers. Cedar releases a distinct, resinous scent as it heats up that many people associate with a traditional sauna experience, especially after water hits the rocks. Heat-treated hemlock is comparatively neutral in scent, which some bathers prefer, particularly anyone sensitive to strong natural aromas or who plans to spend long sessions in the room. Once you know which of these characteristics matters most for your particular install, it genuinely helps to compare finished units side by side rather than pricing raw lumber alone first; see the full lineup to check which wood species each model actually uses before deciding, since not every manufacturer specifies this clearly on a spec sheet.

How does grain and knot pattern affect the finished look?

Clear cedar has a tighter, more uniform grain with few or no visible knots, which gives a finished room a clean, consistent look that a lot of buyers picture when they imagine a high-end sauna. Knotty cedar grades keep the same aroma and rot resistance but show visible knots throughout the paneling, which some people actually prefer for a more rustic, cabin-style look, and it costs meaningfully less than clear grade. Heat-treated hemlock tends to have a straighter, more even grain pattern by nature, with fewer pronounced knots even at lower price points, which is part of why it reads as a slightly more modern, minimal look on the wall next to cedar’s warmer, more varied grain.

Which wood is easier to maintain over the long run?

Both woods hold up well indoors with basic care, a wipe-down after sessions and occasional light cleaning, and neither needs interior sealant, which would trap moisture against the wood in a bad way. The real maintenance difference shows up outdoors, where cedar’s natural oils give it a bit more built-in resistance to the early stages of weathering before a sealant coat is due, while unsealed hemlock left exposed will start showing wear slightly sooner. Neither difference is dramatic enough to be a deciding factor on its own if you’re staying on top of the resealing schedule either way, but it’s worth knowing if a season or two ever slips by without attention.

Which wood is better for anyone sensitive to natural oils or scent?

Heat-treated hemlock is generally the better pick for bathers with fragrance sensitivities or mild wood-oil allergies, since the heat-treatment process removes most of the natural resin that gives cedar its scent and, in rare cases, causes skin irritation on prolonged contact. This doesn’t mean cedar is unsafe for most people, only that hemlock offers a more neutral option if scent sensitivity has been an issue in the past, whether from this specific wood or similar aromatic softwoods.

Which one should you choose for an outdoor build vs an indoor room?

For an outdoor barrel or cabin exposed directly to rain, snow, and sun, cedar’s natural rot resistance gives it a slight edge, though both woods need a sealant reapplied every one to three years to really hold up long term outdoors. For an indoor room protected from weather, the choice comes down more to budget and scent preference than durability, since both species perform similarly well when ventilation is adequate and the room is allowed to dry out fully between sessions.

Frequently Asked Questions

Does cedar fade or gray over time?

Interior cedar generally keeps its color well since it isn’t exposed to sun or rain. Exterior cedar on a barrel or outdoor cabin does gray with UV exposure unless it’s resealed every one to three years with a breathable wood sealant.

Is heat-treated hemlock safe to sit against bare skin at high heat?

Yes. The heat treatment process removes moisture and resin from the wood, which is part of why it stays cooler to the touch than untreated softwoods and doesn’t release sap or a strong scent when heated.

How much more expensive is cedar per square foot than hemlock?

Clear cedar typically runs 20 to 40 percent more per square foot than heat-treated hemlock, depending on grade and supplier. The gap narrows somewhat on lower cedar grades that include more knots.

Which wood is more sustainable to source?

Both can be sourced responsibly depending on the supplier, and it’s worth asking any manufacturer whether their cedar or hemlock carries a forestry certification. Hemlock is often more regionally available in parts of North America.

Can a sauna mix cedar and hemlock in the same build?

Yes, and it’s a common way to manage cost. Some builds use cedar for benches and backrests, where skin contact and aroma matter most, and heat-treated hemlock for wall paneling.