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Thermowood Barrel Sauna: A Smart Choice for Sauna-Led Wellness

There’s something timeless and beautifully organic about sauna bathing in the outdoors. Nature’s most significant elements (water, air, fire) combine to create a relaxing refuge. While traditional and electrical saunas are both excellent choices for enjoying sauna bathing in nature, there’s a type of outdoor sauna with a unique value. 

The thermowood barrel sauna is crafted from unique wood, making it ideal for enjoying a restorative sauna session beneath the skies. The everlasting quality of thermowood, combined with the appealing design of the barrel sauna, produces an ambiance like no other. So, what is it about the thermowood barrel sauna that makes it special? Let's find out.

What is a Thermowood Barrel Sauna? Understanding the Basics

While many believe tropical wood is among the best materials for a sauna foundation, it is not environmentally sustainable. Aside from being expensive, harvesting tropical wood places undue strain on the timber industries across Africa, Latin America, and Asia. Tropical wood can also be sensitive to the rigors of the outdoors. This is where thermowood offers a cut above the rest. The word “thermowood” refers to “thermally modified wood”. Some of its other names include:

  • Heat-treated timber
  • Thermally modified timber
  • Thermal wood 

Thermowood literally walks through fire to provide stability and enhanced durability. It refers to any wood that undergoes high heat exposure or thermal treatment (usually between 185-212 degrees Celsius) to make it stronger. The heat helps extract any residual moisture from the wood, namely two elements:

  1. Hydroxyl (OH)
  2. Water (H20)

Wood naturally contains these elements, contributing to its sensitivity and making it vulnerable to external influences. Removing these constituents yields a robust, heat-treated form of tough wood that will endure for years.  Moisture removal also eliminates all resin from the wood, leaving behind a beautiful finish.

How Does a Thermowood Barrel Sauna Benefit You?

Saunas clad in thermowood provide several unique advantages. 

Excellent Moisture Resistance

Moisture is a nemesis of any wood. In saunas, moisture retention in the wooden construction can shorten its lifespan. With repeated use, the wood can twist, shrink, and become unstable. Aside from disrupting your sauna experience, it can also be dangerous in the long run and cost you hundreds of dollars in repairs and replacement.

A thermowood sauna eliminates this moisture-related barrier. Thermowood is a revolutionary product with outstanding moisture resistance due to its thermal treatment. Exposure to severe temperatures increases the inherent density of the wood. 

This makes it highly resistant to moisture and humidity, both key aspects of a sauna session. Humidity levels in wet saunas can reach 100%. With thermowood cladding, a sauna will absorb only about 12% of this humidity. The result? 

  • A safe, hygienic, and hypoallergenic product
  • Deflects humidity and extreme weather better than other kinds of wood
  • Resistance to rot, fungus, and mold
  • Resin-free elegant finish
  • No shrinking, swelling, warping

Longevity and Stability

A high-quality sauna should last for decades. A thermowood barrel sauna provides this guarantee. The thermowood heat-treatment method alters its molecular structure, making it more stable and durable than untreated wood. Whereas untreated wood can fracture or rot over time, thermowood will not show signs of decay.

Thermowood barrel saunas also preserve their distinct shape and color over time. This is because they have already been subjected to intense heat, which boosts their resistance to humidity fluctuations. They do not expand and shrink as much as untreated wood. 

What does this mean for your sauna? 

Fewer repairs, less upkeep, and reduced costs.

Another reason thermowood outlasts untreated wood is because it doesn’t suffer from resin leakage. Saunas made of pine or spruce wood experience this issue, which can lead to decay and deformation. Because thermowood's treated wood eliminates resin residue, the sauna's panels and inner walls remain immaculate over the years.

Periodic varnish treatment is advisable for thermowood, but it can last for years even without treatment. 


If you’re big on sustainable sauna construction, you’ll love what thermowood offers. Its chemical-free modification avoids toxins or chemical coating, relying on heat to alter its cellular structure.

Its thermally changed structure also allows it to absorb more carbon than untreated wood. Its endurance translates into a longer lifespan, lowering the demand for fresh wood from forests. This means you’ll be able to enjoy your thermally modified barrel sauna for many years to come.

Lightweight and Luxurious Design

Thermowood is more than just a functional material. The thermally modified treatment also results in a lush, exquisite wood design. Thermowood can retain its natural wood finish without any chemical products.

A thermowood sauna takes on a darker color, giving the appearance of fine, stained wood. If you don't varnish it, it will retain its natural glow over time, eventually fading to a silvery grey.

Another advantage of thermowood is its lightweight nature. Because of the lack of moisture, thermowood allows a supple yet robust wooden construction that is easy to assemble and move. This makes it an excellent choice for home saunas. 

Thermowood Barrel Sauna: Our Recommendations

Forever Saunas Thermally Treated 2-Person Sauna

Handcrafted in Northern Europe, this stunning thermowood barrel sauna for two is a fine example of craftsmanship and comfort. This barrel sauna is made of thermo-treated wood with tight knots. 

It is clad in lightweight spruce and smooth aspen wood to deliver the ideal sauna experience. The sauna has a golden tint with a sumptuous finish.

The addition of stainless-steel barrel bands enhances durability. Its arched seating arrangement and benches also provide optimal comfort. The curved roof, sufficient space, and ergonomic design make this sauna a relaxing retreat.

One of the most notable characteristics of this thermowood sauna is its capacity to trap and hold heat, which is essential in high-quality saunas. Thanks to the top-tier insulation of thermowood, a traditional-style stone heater perfectly warms up the barrel sauna. There are two excellent heaters to choose from:

  1. The Harvia KIP heater
  2. HUUM Drop stone heater

The front of the barrel sauna has a bronze tempered glass door, which aids in heat retention. Openings at the back of the sauna provide ventilation. It also has a black shingle roof for protection against the elements. 

Lightweight and convenient, this thermowood barrel sauna kit allows easy assembly at home with a few tools. Some of its other features include:

  • Can accommodate up to three bathers
  • Features heater guard and exhaust
  • LED lighting with E-MOOD lighting upgrade available
  • Wireless connectivity
  • Wireless handheld remote


  • 6’-5” interior height
  • Exterior - 59” long and 81” diameter
  • Interior - 51” long and 77” diameter

Forever Saunas Thermally Treated 6-Person Sauna With Back Window

Enjoy the undisturbed beauty of the outdoors with the thermally-treated 6-person barrel sauna with a lovely back window. Thanks to its ergonomic design and arched backrest, you and your family/friends can make the most of sauna bathing outside. 

The sauna's thermally adapted wooden design ensures a delightful experience. The wood has a smooth finish with no knots, so there are no sharp edges or splinters when you sit. The benches have a big circumference, making them suitable for people of all shapes and sizes. The arc in the barrel provides adequate lumbar support throughout your sauna sessions. 

Your thermowood sauna will last twice as long as a Cedar-wood sauna because of its dimensional stability. Its high R-value thermal resistance is especially noteworthy, providing superior humidity and heat resistance. 

While thermowood is naturally moisture-resistant, the sauna has dual floor drains to drain pool- and rainwater.

Besides its top-of-the-line functional benefits, this 6-person barrel sauna has aesthetic advantages. Enjoy a lavish sauna session any time of day with its waterproof interior LED lighting. 

The dotless lighting technology also creates a soothing glow. You can control all these functions with a handheld remote. If you fancy something extra, opt for the E MOOD lighting package, which provides a spectrum of lighting options to match your sauna setting. 

Sauna sessions are all about unwinding and connecting with nature; this one-of-a-kind barrel sauna allows you to do that. Its half-moon back window adds space to your barrel sauna while providing a view of the great outdoors. Some of its other features include:

  • Air vents and exhaust settings
  • E Sconce+ outdoor wall lighting
  • Black shingle roof kit for weather protection
  • Easy DIY installation


  • 6’-5” interior height
  • Exterior - 87” long and 81” diameter
  • Interior - 78-½” long and 77” diameter

FAQs About the Thermowood Barrel Sauna

Is the Thermowood Barrel Sauna an Environmentally-Friendly Choice?

Thermowood is made from wood sourced from PEFC-certified forests. The thermal treatment involves only heat and steam. No hazardous chemicals are used. 

The thermowood barrel sauna is sustainable because of its toughness and longer lifespan. If used properly, a thermowood sauna can survive for decades, lessening the impact of deforestation.

How Long Does Thermowood Last?

Thermowood is resilient and has a high structural integrity, meaning it can be stable for a long time. It is classified as Class 2 wood and has a lifespan of three decades (as stated by the BRE, aka Building Research Establishment).

Is Thermowood Fire- and Water-Resistant?

Thermowood-clad barrel saunas provide fire- and moisture-resistance qualities. It is resistant to fire since it has already been treated with tremendous heat. It is also resistant to moisture absorption due to its thermal process.

Key Takeaways: Why Choose a Thermowood Barrel Sauna?

Choosing a thermowood barrel sauna is a smart choice for the modern and discerning sauna user. Saunas have been around for a long time, and keeping up with the changing times is essential. 

The thermowood barrel sauna does this wonderfully with its sustainable offerings. Promising excellent durability and stability, the thermally modified wood of the thermowood sauna offers a host of advantages over uncured wood. 

Strong construction, moisture resistance, refined aesthetics, and optimal insulation are some of its benefits. It can adapt well to both indoor and outdoor use and has a longer lifespan than softwood such as cedar. 

Thermowood saunas are more expensive than saunas made from untreated wood. However, they offer great ROI thanks to their decades-long lifespan. They also require little upkeep and incur lower repair costs over time.

If you’re looking for a high-quality thermowood barrel sauna, Forever Saunas offers an excellent, ready-to-ship range. 

Made from top-tier materials, you can choose from a range of 2-person, 4-person, and 6-person saunas. Feel free to contact us for more information; our staff will gladly assist you.

Use coupon code WELCOME10 for 10% off your first order.


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