What’s the Best Wood for a Sauna?

When designing a sauna or buying a prefabricated one, choosing the right type of wood for you and your environment is crucial. Not only does your sauna wood choice contribute in a big way to the aesthetics; the physical qualities of the wood also play a significant role in maintaining the sauna’s heat, creating a comfortable, inviting environment, and the sauna’s long-term durability.

In this article, I describe the most popular sauna woods for sauna building, both for indoor and outdoor applications; including traditional and infrared saunas, for indoor use, and for your own backyard.

Note that many people are allergic to the chemicals in certain types of wood. If you’re someone who is prone to allergies, then you’ll also want to know which woods to avoid.

Summary

Softwood has it over hard wood for sauna construction, not only because it grows faster and is therefore a more available and environmentally-friendly choice. Softwood is also more heat resistant within the sauna space, so it’s less likely to overheat and cause burns.

Among the softer woods, cedar and hemlock are currently among the most popular wood types for outdoor saunas; though other woods such as pine and spruce are also popular.

Cedar wood is generally regarded as the best choice, for both aesthetic and practical reasons:

• Aroma: Cedar has a distinct and pleasant scent that enhances the sauna experience
• Resistance: Cedar contains natural oils & resins, making it highly resistant to decay, pests & rot
• Thermal qualities: Cedar has excellent thermal insulation properties, helping to retain heat within the sauna
• Durability: While not a hardwood, afficionados know cedar for its strength and longevity

On the flip side, cedar does have a few disadvantages:

• Cost: Cedar is usually more expensive than other sauna wood options
• Fading: Over time, cedar wood will fade in color, unless you regularly maintain and treat it
• Chemical: The same odor (and volatile oils) that repel insects, can provoke an allergic reaction in sauna users

Hemlock runs second to cedar in North America, as a faster-growing and often cheaper alternative. Other advantages include:

• Heat distribution: Hemlock has good heat conductivity, so it distributes heat evenly throughout the sauna
• Lower allergenic potential: sauna users report fewer allergic reactions to hemlock than they do to cedar cabins

Hemlock does have significant disadvantages though, especially for outdoor use, as it has a tendency to splinter during machining. Then it’s prone to bow or warp over time when exposed to the extremes of sunlight and the elements.

Other increasingly popular choices for sauna construction include: eucalyptus, basswood, pine, poplar, redwood, and spruce.

Indoor Sauna Wood Type

Cedar

Cedar is undoubtedly one of the most popular choices for indoor saunas, especially in traditional Finnish-style saunas. Its natural scent and resins give off a pleasant aroma while releasing therapeutic oils, perceived to have health benefits.

Additionally, cedar wood is highly resistant to decay and offers excellent insulation, which helps to maintain the sauna’s heat efficiently.

Canadian Hemlock

Canadian Hemlock (Tsuga canadensis) is another leading option for indoor saunas. Its light color and beautiful, knot-free grain patterns, clearly shown here, create a gentle, calming atmosphere.

And hemlock is among one of the more durable and stable woods, adding to its popularity for sauna construction. Also, this wood type has low resin content, reducing the risk of allergic reactions, providing a clean and safe sauna experience.

Hemlock’s not generally the best choice for sauna benches, though, given its rough surface finish.

Basswood

Basswood (AKA American Linden) is an excellent choice if you want a soft and light-colored wood for your indoor sauna. It has excellent heat insulation properties, ensuring efficient heat retention.

Basswood’s also resistant to warping and cracking, which makes it incredibly durable and long-lasting. On the downside, not everyone appreciates the unusual odor that Basswood gives off.

Outdoor Sauna Wood Types

Redwood

Redwood is a popular choice for outdoor saunas due to its natural resistance to decay, insects, and moisture.

The stunning appearance of redwood, with its rich hues and distinct grain patterns, creates its love-at-first-sight attraction. Bear in mind, though, that the color will fade over time.

Otherwise, redwood needs minimal maintenance and can withstand various weather conditions. That makes it an excellent choice for outdoor sauna enthusiasts.

Western Red Cedar

Similar to redwood, western red cedar (Thuja plicata) offers exceptional durability and resistance to the elements. That’s a key attribute for outdoor sauna construction. The wood’s natural oils act as preservatives, protecting the wood from rot and decay, even in the harshest outdoor conditions.

Western Red Cedar provides a beautiful aesthetic with its reddish-brown color and pleasant aroma, enhancing the overall sauna experience.

Traditional Finnish-Style Saunas

Finnish Pine

Builders of traditional Finnish saunas, often choose pine wood for its pleasant scent, light color, and affordability. Pine provides a warm ambiance and absorbs moisture efficiently, making it a great material for a comfortable sauna environment.

For the budget conscious, pine is one of the cheapest woods available for sauna construction. Drawbacks are that it needs regular maintenance and may not last as long as other woods. Also, knots are common in pine planks, which can overheat and then fall out over time.

Finnish pine, though, does contribute a lot of authenticity to the traditional sauna experience.

Nordic Spruce

Spruce wood is another popular choice for Finnish-style saunas. Its light color and subtle scent create a cozy and traditional atmosphere.

Spruce is known for its thermal insulation properties, improving heat retention. That makes it an ideal choice for achieving an authentic Finnish sauna.

Infrared Sauna Wood Types

Hemlock

Hemlock, as mentioned earlier, is also a fantastic wood option for infrared saunas.

The wood’s low resin content minimizes the emission of volatile organic compounds (VOCs). That ensures a healthier breathing environment during infrared sauna sessions.

Additionally, hemlock wood offers excellent heat insulation. The insulation maximizes the efficiency of the sauna’s infrared heating systems. (See the section of exterior panelling from an infrared sauna model that I’ve illustrated here.)

Poplar

Poplar wood is gaining popularity in infrared saunas due to its high resistance to warping and its stability under high temperatures. The poplar species in North America includes three broad groups of trees – cottonwoods, aspens and balsam poplars – and which belong to the willow family. It’s also one of the most affordable sauna woods used in construction, being at the softer end of the hardwood range. This wood is also widely available.

Poplar emits fewer VOCs compared to other wood types, it has no exposed knots and doesn’t easily splinter, secrete resin, or overheat. These qualities are key to a cleaner sauna experience. And the wood’s light color and attractive grain patterns can add a touch of elegance to an infrared sauna’s interior.

The aspen planks illustrated (above left) have been thermally modified to remove the wood’s natural moisture. Note that they’re also finished smoothly on all sides. Perfect for sauna benches!

Frequently Asked Questions

What other woods can you use for sauna construction?

Other popular types of wood for building saunas include: Black Alder, Douglas Fir, Chinese Fir, Eucalyptus and Black Alder.

What woods should you not use for saunas?

Harder woods, like oak, teak, or mahogany, have a tendency to overheat – and therefore cause burns – when they are exposed to high temperatures. So, they are definitely not recommended, either for interior walls or benches. Similarly, woods that produce a lot of sap, such as maple and walnut, are best avoided.

Does sauna wood need treating?

The short answer is yes, both before and after installation. If you’re buying a prefabricated sauna for home assembly, you can expect the wood components to have received an appropriate protective treatment before despatch. The right treatment will depend on the wood type, and whether it’s intended for indoor or outdoor use.

Once installed, sauna wood also needs periodic cleaning and maintenance; ideally once or twice a year. But not all woods are the same in this respect, so do check the manufacturer’s instructions on the care and maintenance of your particular sauna.

The leading sauna manufacturers recommend a variety of products from paraffin oil, to clean and protect the benches, to organic wood oil, to keep your sauna fresh and free from pests and mildew. Not forgetting the underside of benches, where mould typically first begins to grow.

But, whatever you do, never paint, stain or varnish the interior wood in your sauna. Not only would this inhibit the wood from releasing humidity, which can damage the wood and potentially warp or crack the panels over time. The product you use may also release toxic fumes while the sauna’s in use.