Natural wood has long been one of the most popular building materials. Architects and designers continue to specify wood for its sustainability and character, and builders know how to install it properly. Plus, studies suggest that natural wood can have physiological benefits when used as a building material.
The downside with real wood is its performance over time, particularly in demanding environments. Since wood is a natural material, it requires maintenance and care, and harsh conditions may affect its longevity.
Thermally modified wood offers a solution to these challenges. Read more to learn how thermally modified wood is made and the key benefits it offers.
Key Takeaways
- Thermally modified wood is made using a chemical-free process with high heat and steam
- Thermal modification improves the dimensional stability of natural wood
- Thermally modified wood is suitable for a variety of interior and exterior applications, including siding, paneling, and decking
- Thermally modified wood performs well in harsh mountain climates due to its enhanced characteristics
What is Thermally Modified Wood?
Thermally modified wood is natural wood that has been permanently altered at the cellular level using high heat and steam. Thermal modification is intended to improve the stability and durability of natural wood without the use of chemicals.
Modern thermal modification techniques were developed in Northern Europe in the 1990s, though evidence of thermally modified wood dates all the way back to Ancient Egypt. Today, thermally modified wood is widely specified for high-performance architectural applications where natural aesthetics and sustainability are desired.
Thermal Modification Process
Many companies around the world make thermally modified wood. Finland-based manufacturer Lunawood, a global leader in thermally modified wood products, uses a patented eco-friendly thermal modification process with three steps.
Step 1: High-Temperature Drying
First, the wood enters the kiln for high-temperature drying. Heat removes moisture from the wood, and evaporated steam prevents cracking or burning. Moisture content in the wood is reduced to near zero percent.
Step 2: Thermal Modification
Next, a steady high temperature is maintained in the kiln. In this stage, thermal modification occurs, as the wood undergoes chemical and physical changes. The color of the wood darkens due to heat, and extractives that contribute to decay are removed.
Step 3: Cooling with Steam
Finally, steam is used inside the kiln to reduce the temperature of the wood, and material moisture content stabilizes around 4-7%, depending on the species. This improves the stability and durability of the wood with minimal risk of cracking.
Once thermal modification is complete, the wood is ready for quality control and milling.
Benefits of Thermally Modified Wood
Thermally modified wood has many benefits, from performance to sustainability.
Dimensional Stability
Due to its lower moisture content, thermally modified wood is less prone to expansion and contraction than regular wood.
Aesthetics
Thermally modified wood has smooth, dark tones which designers consistently select for mountain modern applications. Plus, thermally modified wood often has a more pronounced aroma than regular wood.
Sustainability
In this day and age, sustainable building materials are in high-demand. While engineered materials are designed for durability, they often lack the warmth and natural character of real wood and may involve more energy-intensive processes.
Thermally modified wood is considered one of the most sustainable building materials available. Key benefits include:
- Chemical-Free: thermal modification does not require any chemicals (only heat and steam).
- Low Energy Consumption: compared to many non-wood exterior materials, thermally modified wood typically requires less energy to produce and transport
- Low Waste Factor: thermally modified wood is less prone to damage, which reduces waste factor on job sites and therefore lowers costs.
- Biodegradable: when thermally modified wood can no longer be used, it will degrade naturally since it is made of real wood.
Learn more about the sustainability of thermally modified wood on the International ThermoWood Association website.
Maintenance
Unlike ordinary wood, thermally modified wood products such as Lunawood do not necessarily require surface treatment in any climate. Finish may be applied to alter the color for aesthetic purposes, but thermally modified wood will still perform if left untreated.
Some thermally modified products such as Lunawood undergo a natural greying process over time. Low moisture content combined with UV exposure and weathering contribute to this gradual color change, which may take years depending on the environment.
Applications
Thermally modified wood is suitable for both indoor and outdoor applications. The most common applications include:
- Exterior siding
- Exterior paneling / soffits / trim
- Interior paneling
- Decking
Thermally Modified Wood for High Altitude
Mountain environments create harsh conditions for construction. When specifying materials in such areas, architects and designers must consider factors such as low humidity, temperature swings, intense UV exposure, and weathering.
Thermally modified wood is an excellent material for mountain modern projects that require the timeless character of natural wood coupled with improved durability and performance.
Conclusion
So long as lumber is harvested responsibly and international forest management is properly regulated, natural wood will continue to be used as a building material. Thermal modification offers an upgrade to natural wood by reducing wood moisture content and thus improving performance over time. Not only is thermally modified wood designed to last, but it is also aesthetically attractive and sustainable compared to engineered materials.
Thermal modification may well represent the future of natural wood as a building material. For architects and designers who want the look and feel of real wood without the downsides, particularly in harsh mountain environments, thermally modified wood is the best solution.
Learn more about thermally modified wood for the Rocky Mountain Region on our Lunawood Collection page.
External Links
International ThermoWood Association
Study: Durability of Thermally Modified Wood
Study: Physiological Benefits of Natural Wood
