Thermal Ash

Thermal Ash is a long lasting and beautiful natural thermally modified wood product perfect for decking and cladding. 


Thermally Modified Wood

Thermally modified wood is a type of wood that has been subjected to a heating process to alter its physical and chemical properties. This process is usually carried out in a controlled environment using steam or heat, and it is designed to improve the wood’s durability, weather resistance, and overall strength.

During the thermal modification process, the wood is heated to temperatures of between 160°C and 220°C. This process causes the wood to undergo a series of chemical reactions that alter the structure of its cells. The result is a wood that is more stable and resistant to moisture and decay than untreated wood.

Thermally modified wood has a number of advantages over other types of wood. It is less susceptible to warping, cracking, and splitting, and it is more resistant to insects and fungal decay. It is also more consistent in terms of its color and grain pattern, and it has a unique, attractive appearance.

While thermally modified wood has a number of advantages, it can also be more expensive than other types of wood. It is also more difficult to work with and may require special equipment and techniques during installation. However, for projects that require a durable, weather-resistant, and attractive wood material, thermally modified wood can be an excellent choice.

Thermally Modified for Maximum Sustainability

Thermal modification begins by heating the wood to 450º Fahrenheit in a vacuum with all oxygen removed from the space. While Ash will combust at 300º Fahrenheit,  the removal of the oxygen prevents combustion and allows the sugars in the wood to caramelize. The caramelizing of the sugars gives the Ash the dark brown colors and essentially begins a petrification process which makes the wood water resistant. The life expectancy of cladding and decking made from Thermal Ash is about twenty five years. 

Color of thermal ash:

The color tone of Thermal Ash is a fantastic range of deep browns and brownish red hues, think about the crust of Crème Brûlée. The caramelized sugars create these colors throughout the wood, making it an absolutely gorgeous wood. 


  1. Decking: Thermal ash is often used for decking due to its improved resistance to decay, insects, and weathering, making it a durable and low-maintenance option for outdoor spaces.

  2. Cladding: It is utilized as exterior cladding for buildings, providing both a visually appealing and durable solution for protecting structures from the elements.

  3. Furniture: Thermal ash is used in the manufacturing of outdoor furniture, as the treatment process enhances its resistance to environmental stresses, ensuring longevity and aesthetics.

  4. Flooring: As a durable and stable material, thermal ash is employed in flooring applications, particularly in areas with varying humidity levels, where its resistance to warping is advantageous.

  5. Siding: It is commonly used for siding on homes and other structures, offering a durable and attractive solution for protecting exteriors.

  6. Landscaping: Thermal ash is used in various landscaping applications, such as for retaining walls, garden borders, and other outdoor structures that require resilience against weathering.

  7. Shingles: Thermal ash shingles are employed for roofing applications, providing a durable and aesthetically pleasing solution for both residential and commercial structures.

  8. Interior Paneling: In addition to exterior uses, thermal ash is utilized for interior paneling, adding a touch of warmth and durability to indoor spaces.

  9. Utility Poles: The treated wood is sometimes used for utility poles, benefiting from its improved resistance to decay and insects, which extends the lifespan of these essential structures.

Fun Fact about Thermally Modified Ash Wood:

Thermally modified wood is all rage in the United States at the moment and for good reason. Well known as an excellent product for exterior and interior wood paneling/cladding, but it's also been accepted and utilized by the musical instrument industry. Acoustic and electric guitar manufacturers have taken a liking to Thermally Modified Ash for it's acoustic vibration properties and it's inherit stability. 

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We typically offer Thermal Ash in the following sizes and grades:

Scientific Sub-species Grade Features 4/4 5/4 6/4 8/4 12/4 Plywood Circle Sawn Live Edge Beam
Fraxinus Americana Ash Clear Thermally modified wood to be more water resistant, dark color tones, beautiful grain

Scientific information about Thermal Ash:

Exterior Wood Cladding and Siding Exterior Wood Decking
Molding and Trim T/G Siding and Paneling
Butcher Blocks Plank Tops

Check out some species other than Thermal Ash

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Give us a call or shoot us an email, we can help you find the right kind of wood to make your project look fantastic! From kiln dried lumber to flooring, molding to butcher butcher block counter tops, we've got you covered.