Sauna Design
Cedar vs Hemlock Outdoor Sauna: Which Wood Wins?
For an outdoor sauna, Western Red Cedar is the better wood, and outdoors the gap is wide: cedar's natural oils win 8 of 10 durability-related properties and give it a 15-25 year lifespan versus roughly 10-15 years for hemlock. The reason is simple. Cedar's defences against rain, rot, mould and insects are built into the wood, while hemlock relies on applied coatings that break down under sun and freeze-thaw. Hemlock still earns its place as the budget and indoor pick, costing 2-3x less. Below is the head-to-head, a full property table, and where each wood actually belongs.
Key Takeaways
- Cedar wins outdoors on durability. Western Red Cedar's thujaplicin oils resist moisture, rot, mould and insects with no coating, taking 8 of 10 sauna-wood properties.
- Hemlock's one clear edge is price. It costs roughly 2-3x less than cedar, which is why most budget outdoor cabins are hemlock.
- Lifespan favours cedar. Expect about 15-25 years from cedar versus 10-15 from hemlock, and the gap widens outdoors as coatings degrade.
- Wood choice matters more outdoors than indoors. Rain, UV, insects and freeze-thaw punish coating-dependent hemlock in ways a climate-controlled indoor room never does.
- Hemlock is still right for some buyers - protected indoor installs, scent-sensitive users and budget-first first-timers.
- Skip the lumberyard guesswork. Compare complete cedar and hemlock builds in the Calore saunas collection.
Cedar or hemlock outdoors: the short answer
Choose Western Red Cedar for any outdoor sauna, and choose Canadian Hemlock only when budget or a protected indoor location makes its trade-offs acceptable. The two woods perform closely on the things you feel in a single session - both stay comfortable to the touch and both hold heat well. They diverge on the things you feel over years of ownership: moisture, rot, insects and weather. Cedar carries natural oils that handle all four; hemlock does not, so outdoors it leans on coatings that wear out.
That single distinction - inherent protection versus applied protection - is the whole comparison in miniature, and it is why cedar is the default material for premium outdoor saunas while hemlock dominates the budget shelf.
Western Red Cedar: what makes it the outdoor standard
Western Red Cedar is the benchmark outdoor sauna wood because its natural thujaplicin oils give it moisture, rot, mould and insect resistance without any chemical treatment. Those oils are not a coating that sits on the surface - they are part of the wood's cellular structure, so they do not wash off, peel or degrade under UV. That is the property that matters most when a cabin lives outside through rain, snow and sun.
The durability claim is well documented in wood science. The USDA Forest Products Laboratory classifies Western Red Cedar heartwood as resistant to decay, placing it among the most naturally rot-resistant North American softwoods without treatment. Cedar is also low in density, which gives it low thermal conductivity: the wall and bench surfaces stay comfortable against bare skin even as the air passes 82°C (180°F), and the cabin insulates and holds heat well. Add the warm, calming aroma many people associate with a traditional sauna, and cedar covers durability, comfort and experience at once.
Stat: Cedar's natural oils help it resist moisture, rot, mould, mildew and insects with zero applied coating - the reason it typically lasts 15-25 years outdoors and needs less maintenance than any coating-dependent wood.
Canadian Hemlock: the budget and indoor contender
Canadian Hemlock is the wood buyers reach for when they want cedar's thermal comfort without cedar's price or scent - and it delivers that, with one important limitation outdoors. Hemlock is structurally strong, pale and uniform in appearance, and nearly odourless, which makes it a genuine favourite for anyone sharing a sauna with a fragrance-sensitive household or who simply prefers a neutral interior.
Where hemlock falls short is natural weather defence. It has minimal thujaplicin content, so it offers limited resistance to moisture, rot, mould and insects on its own. Indoors, in a climate-controlled room, that rarely matters - the wood faces heat and humidity during a session, then returns to a dry room. Outdoors it matters a great deal, because hemlock's protection then depends on paint, sealant or weatherproofing applied to the surface. Those coatings are a barrier that degrades over time, and when the barrier fails the bare wood has little to fall back on.
Cedar vs hemlock, head to head
Across the properties that define an outdoor sauna wood, cedar leads on durability, weathering, heat and maintenance, while hemlock leads on cost and ties on skin-contact comfort. Here is how the two woods compare on each factor that actually shapes an outdoor build.
Durability and rot resistance
Cedar wins clearly. Its oils repel moisture at the cellular level and inhibit the fungi that cause rot, so it holds structural integrity through thousands of humid sauna sessions. Hemlock absorbs moisture more readily and, without maintained coatings, can swell, warp or rot in wet conditions - the risk is highest outdoors where rain exposure is constant.
Scent and skin contact
This one splits by preference. Cedar releases its signature warm aroma when heated, which many buyers consider part of the ritual; hemlock is nearly scent-free, which suits anyone sensitive to strong fragrance. On skin contact the two effectively tie - both have low thermal conductivity and stay comfortable to lean against at sauna temperatures.
Cost
Hemlock wins on price, and it is not close. Cedar typically costs 2-3x more, and because the wood is a major share of a sauna's cost, that gap is the single biggest reason budget outdoor cabins are built from hemlock while cedar cabins sit at the premium end.
Heat behaviour and outdoor weathering
Cedar edges ahead on both. Its low density supports even heat distribution and strong insulation, and its low shrinkage rate means it resists warping and cracking through the constant heat-up and cool-down of daily use plus the seasonal freeze-thaw of a Canadian yard. Hemlock handles thermal cycling adequately but is more prone to movement over years of it, which can loosen joints. Outdoors, cedar grays gracefully under UV while keeping its structure; hemlock's UV-exposed coatings are what fail first.
Why wood choice matters more outdoors
An outdoor sauna faces a fundamentally harsher environment than an indoor one, and that is exactly where cedar's inherent protection pulls away from hemlock's applied protection. Indoors, a cabin sits in a controlled room and only meets heat and humidity during a session. Outdoors, it meets rain and snow, months of UV, freeze-thaw temperature swings, insects, and the same hundreds of thermal cycles per year - all at once, year-round.
The core issue is where the protection lives. Cedar's defences are inside the wood and last its full lifespan. Hemlock's defences are on the surface, and every season of sun, water and wear chips away at them. For a climate-controlled indoor build the distinction may barely register; for an outdoor cabin it compounds with every winter.
Stat: An outdoor sauna endures roughly 300-500+ heat-up-and-cool-down cycles a year on top of seasonal freeze-thaw - the cumulative stress that separates cedar's built-in durability from a coating that needs renewing.
The right choice for a Canadian outdoor climate
For a Canadian outdoor sauna, cedar is the clear pick, because our climate stacks every stress that favours it: heavy freeze-thaw cycling, snow load, humid summers and strong seasonal UV. A wood whose protection degrades with weather is working against the environment here, while a wood whose protection is inherent is working with it. That is why Western Red Cedar is the standard material for premium outdoor cabins across Canada.
At Calore we build in both woods - Western Red Cedar and Canadian Hemlock - and match them to the job. Cedar goes where its natural moisture, rot and insect resistance earns its keep, which for a four-season outdoor cabin is nearly always. Hemlock is offered where a neutral, near-odourless interior or a lower entry price suits a protected install. If you want to see the two side by side, our cedar barrel sauna and black cedar sauna chamber show what full cedar construction looks like for outdoor use. For a broader look at every sauna wood beyond these two, see our guide to what kind of wood is best for a sauna.
Safety - never seal, stain or paint sauna-interior wood. Whichever wood you choose, the interior surfaces of a sauna are left unfinished on purpose. Sauna heat accelerates off-gassing, and paints, stains, varnishes and sealants release volatile compounds you would then breathe at temperature. Outdoor weatherproofing belongs only on exterior surfaces, never on interior cladding or benches. Avoid pressure-treated or chemically treated lumber inside a sauna entirely, and confirm any structural or electrical work with a qualified contractor to local code before you build.
Full comparison table
This table maps each outdoor-relevant property to a winner, so you can match the wood to your own priority rather than a single verdict.
| Property | Western Red Cedar | Canadian Hemlock | Winner |
|---|---|---|---|
| Moisture resistance | High - natural oils repel water | Low to moderate - absorbs readily | Cedar |
| Rot & decay resistance | Naturally rot-resistant (USDA-classified) | Needs surface treatment to resist decay | Cedar |
| Antimicrobial (mould/mildew) | Yes - oils inhibit mould and bacteria | Minimal - depends on coatings/ventilation | Cedar |
| Insect resistance | Yes - oils deter insects | Low natural resistance | Cedar |
| Stability under thermal cycling | High - low shrinkage, resists warping | Lower - more prone to movement | Cedar |
| Heat retention & insulation | Excellent - low density | Good - cools slightly faster | Cedar |
| Skin-contact comfort | Stays cool to the touch | Stays cool to the touch | Tie |
| Aroma | Warm cedar scent | Near-odourless | Preference |
| Maintenance | Lower - protection is inherent | Higher - resealing & inspection | Cedar |
| Cost | Higher (2-3x hemlock) | Significantly lower | Hemlock |
The scorecard: cedar leads 8 of 10 properties, hemlock leads 1 (cost), and one is a tie with one preference-dependent. Cedar's wins cluster precisely where an outdoor cabin is tested - moisture, rot, insects, mould, stability and low maintenance. Hemlock's win is concentrated entirely in price.
When hemlock is still a reasonable choice
Hemlock is not a bad wood - it is the right wood for specific buyers whose conditions neutralise its outdoor weaknesses. If your situation matches one of these, hemlock's lower cost is a genuine advantage, not a compromise.
- Protected indoor installs. In a climate-controlled room with good ventilation, hemlock faces no rain, UV, insects or freeze-thaw, and can last 10-15 years with appropriate care.
- Budget-first first-timers. If you are testing whether the sauna habit sticks, a hemlock cabin is a legitimate, lower-cost entry point you can upgrade later.
- Scent-sensitive users. Hemlock is nearly odourless, so anyone who finds cedar's aroma too strong will genuinely prefer it - the one property where hemlock is chosen on merit, not price.
- Allergy or sensitivity concerns. Because hemlock lacks the natural oils some people react to, it can be the safer pick for users sensitive to cedar's thujaplicins.
Expert Verdict
Cedar and hemlock are close on the experience of a single session, but an outdoor sauna is a decade-long relationship with weather, and that is where they part ways. Cedar carries its protection inside the wood; hemlock wears its protection on the surface, where Canadian rain, UV and freeze-thaw slowly strip it away. If the budget stretches to cedar for an outdoor build, take it - the premium buys a longer life and far less maintenance. Reserve hemlock for protected indoor rooms, scent-sensitive users, or a first-timer's budget cabin. Key finding: cedar wins 8 of 10 outdoor durability properties and lasts roughly 15-25 years versus 10-15 for hemlock, which makes it the stronger long-term investment for any four-season outdoor sauna. Compare finished cedar and hemlock builds in the Calore saunas collection.
Frequently Asked Questions
Is cedar or hemlock better for an outdoor sauna?
Cedar is the better wood for an outdoor sauna. Western Red Cedar's natural thujaplicin oils resist moisture, rot, mould and insects without any applied coating, which is exactly what an outdoor cabin needs when it faces rain, snow, UV and freeze-thaw cycling year-round. Hemlock has almost none of that natural protection, so outdoors it depends on sealants and coatings that break down over time. Cedar wins 8 of 10 durability-related properties; hemlock's one clear advantage is a lower price. For a protected indoor or infrared sauna, hemlock is a reasonable budget choice, but for an outdoor build in a Canadian climate, cedar is the standard for a reason.
How long does a hemlock sauna last compared to cedar outdoors?
Industry estimates put Western Red Cedar at roughly 15 to 25 years and hemlock at about 10 to 15 years with proper maintenance. Outdoors the gap tends to widen, because hemlock's protection comes from applied coatings that degrade faster under rain, UV and freeze-thaw, while cedar's protection is built into the wood's oils and lasts its full lifespan. A hemlock outdoor sauna can reach the top of its range, but only with a disciplined resealing and inspection schedule that cedar does not demand.
Can hemlock be used for an outdoor sauna?
Yes, with caveats. Hemlock outdoor saunas exist and function, but hemlock lacks cedar's natural resistance to moisture, rot, mould and insects, so it relies on paint, sealant or weatherproofing for outdoor protection. Those coatings degrade from UV, rain, temperature cycling and physical wear, and once a coating fails the bare wood is exposed to conditions it cannot naturally resist. If you choose hemlock for an outdoor build, plan for more frequent resealing, repainting and inspection than cedar requires.
Why do budget outdoor saunas use hemlock instead of cedar?
Because hemlock costs roughly two to three times less than cedar, and the wood is one of the single largest cost drivers in a sauna. That price gap is the main reason budget cabins can sell for a few thousand dollars while cedar-built saunas cost considerably more. For budget-first buyers, hemlock is a legitimate value proposition. But the lower price reflects a wood with less natural protection, a shorter expected outdoor lifespan and higher maintenance, so the day-one saving becomes an upkeep obligation over the years you own it.
What are the disadvantages of hemlock wood in a sauna?
Hemlock's main disadvantages are low natural rot and moisture resistance, minimal antimicrobial and insect defence, and less dimensional stability under repeated heating and cooling. Because it lacks cedar's protective oils, an outdoor hemlock sauna depends on coatings that must be renewed, and if they fail the wood can swell, warp or develop mould faster than cedar would. Its advantages are real too: it is inexpensive, structurally strong and nearly odourless, which suits scent-sensitive users and protected indoor installations.
Which wood does Calore use in its outdoor saunas?
Calore builds its saunas in Western Red Cedar and Canadian Hemlock, the two woods this comparison is about. Cedar is used where its natural moisture, rot and insect resistance earns its place, especially on outdoor and daily-use cabins in Canadian climates, while hemlock's clean, near-odourless character suits buyers who want a neutral interior or a lower entry price for a protected install. You can compare complete cedar and hemlock builds in the Calore saunas collection rather than sourcing and grading lumber yourself.
