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. 

A Beautiful Dark Brown

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. 


While Thermal Ash can be used for just about anything, it's weather resistant properties make it perfect for exterior wood cladding and wood decking. The most popular uses for Thermal Ash are: 

  • Exterior Wood Cladding
  • Wood Decking
  • Exterior Furniture 
  • Wood Siding
  • Shutters
  • Wood Trim
  • Moulding
  • Cabinetry

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

Contact us Have questions about our products?

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.