5 Reasons Why Thermowood is the Best Wood for Saunas

Saunas have a rich history that dates back centuries, offering relaxation, rejuvenation, and a host of health benefits. In Finland, our oldest saunas were built in the Stone Age date back 10,000 years ago, when saunas were taken in a pit dug into the ground.

While their design and construction have evolved over time, the use of wood in saunas remains a constant due to its natural warmth and aesthetic appeal. Among various sauna wood options available, Lunawood Thermowood has gained prominence as a preferred material for sauna construction, combining the inherent qualities of wood with enhanced durability and stability, not to mention the pure, safe, and hygienic aspects.

In this article, we explore the key reasons why Lunawood Thermowood should opt for preferred material.


Photo above: Cabin Havsstrand by Plusarkkitehdit, Photographer: Hans Koistinen

A luxorious sauna and spa in Talo Pukkila, Finland. Photo Katri Hiukka

Why Lunawood ThermoWood® is the Best Wood for a Sauna?

Lunawood ThermoWood® is a special type of wood that has undergone a patented thermal modification process, resulting in improved properties that make it ideal for sauna construction. Typically, Nordic softwoods like pine or spruce are used for Thermowood production. The wood is heated to temperatures 212 degrees Celsius the absence of oxygen. This thermal modification alters the wood’s cellular structure, enhancing its stability, durability, and resistance to moisture. Thermowood’s brown, rich color and natural grain patterns lend a touch of sophistication and visual allure to saunas.

Cabin Havstrand's modern sauna benches and ceiling are made of Lunawood Thermowood. Photo: Hans Koistinen

1. Durability & Stability: Key Qualities of Wood for Saunas

Thermowood stands out with its exceptional durability and stability, making it an ideal choice for sauna construction. The heat treatment process that Thermowood undergoes fundamentally alters its cellular structure, rendering it highly resistant to warping, cracking, and decay. This means the saunas you manufacture will not only withstand the rigors of high temperatures and humidity but also maintain their structural integrity over time, reducing the need for frequent repairs and replacements.

Fluctuations in temperature and humidity are inevitable in sauna and spa environments. Lowered equilibrium moisture content of Lunawood Thermowood makes it dimensionally stable and the material retains its shape far better than untreated wood.

By choosing Thermowood, manufacturers can deliver products ensuring customer satisfaction for years to come. Thermowood sauna withstand the rigors of high temperatures and humidity which are more stable and requiring less maintenance. Over the time reducing the need for frequent repairs and replacements.

2. The Importance of Moisture and Resin Resistance in Wood for Saunas

Moisture is a constant in saunas, and it can take a toll on the materials used in construction. Thermowood’s reduced moisture absorption capacity is a game-changer in this regard. By selecting Thermowood, manufacturers can offer products that resist swelling, degradation, and other moisture-related issues, resulting in longer-lasting saunas that maintain their visual appeal.

Due to the thermal modification Lunawood Thermowood products are pure, safe, and hygienic for indoor use, even for allergy suffers who are prone to wood-related reactions. From the visual point of view, Lunawood Thermowood retains its colour beautifully and does not secrete any resin through the paints or tints. Thanks to the resin-free property, the knots don’t show up through paints or tints even over time. Lunawood recommends use of paraffin oil to ensure high hygienic level in saunas.


3. Lowered Thermal Conductivity: A Must for Sauna Wood

In the context of saunas, thermal conductivity does matter to a certain extent. Thermowood has a lower thermal conductivity compared to untreated sauna wood. It is only 0,09 W/(m K) tested according to EN ISO 13787 and EN 12667. Low thermal conductivity correlates directly with user comfort as sauna users often come into direct contact with the benches and walls. If these surfaces have high thermal conductivity, they can feel uncomfortably hot to the touch, potentially leading to discomfort for the users. Lower thermal conductivity can help maintain a more comfortable surface temperature for prolonged sauna sessions.


4. Easy Machineability: Why It Matters in The Wood for Sauna

Processing does not affect the unique performance properties of Lunawood, as it is modified throughout. Sanding may not be needed with Lunawood as quality of the planed surface is so good. Sawing Lunawood is just as easy as sawing ordinary wood. Wear dust mask and eye protection when machining the Lunawood.

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5. Commitment to Sustainability

Sourced from sustainably managed Finnish forests and subjected to a chemical-free thermally modification process, Thermowood is an environmentally conscious choice that resonates with people who prioritize sustainability. Lunawood products absorb five times more carbon than is released during their production. By offering saunas made from Lunawood you can attract a growing market segment that values ethical and responsible products.

Learn more about our sustainability actions.

Thermowood's low thermal conductivity helps to maintain a comfortable surface temperature on sauna benches

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