- The terms Thermally Treated and Thermally Modified are interchangeable.
- Thermally Treated Wood is softwood or hardwood lumber that has undergone a modification process that heats the wood to over 400 degrees Fahrenheit (over 200 degrees Celsius) in an oxygen free kiln, essentially changing the chemical makeup of the wood fiber. The process “cooks” the wood.
- The thermal treatment process burns the poly sugars which makes the wood water repellant on a molecular level.
- It is natural and non-toxic.
- The thermal treatment not only increases the durability of the wood, but it also increases its dimensional stability.
- The thermal treatment process first started in Finland in the early 1990’s. There are now multiple types of thermal treatment processes in use around the world.
- Thermally treated wood is used for decking, siding, lattice panels, fence boards, garden furniture, doors, and windows just to name a few.
- Tests have shown that thermally modified wood is classified as very resistant to rot with an expected lifetime of more than 25 years.
- Thermally treated wood is a great alternative to old growth softwood species as well as tropical hardwoods.
Ask your local building materials distributor if they carry Thermal Treated wood products and if they do I recommend that you go and see it yourself.
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What a beautiful product! Thanks for sharing @David_Stallcop
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How long does the wood need to be thermally treated to display the benefits? Is it extremely timely or not yet an efficient process? This seems like a potentially very attractive integration for the industry.
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Hello @Madison_Hibner. As far as I am aware, there are 6 different types of processes that can be used to thermally modify either softwood or hardwood lumber. The time it takes to thermally treat can vary depending on the starting moisture content of the wood fiber. If it is dried between 12 and 18% in a standard dry kiln prior to the thermal treatment process then it could take around 24 hours to thermally treat softwood lumber and 2~3 days to thermally treat hardwood lumber. Hardwood lumber has to be treated at a higher temperature compared to softwood lumber. One of the 6 processes for treatment takes up to 7 days to complete the hydrothermolysis, dry curing and conditioning process. While I was at the Carrefour Du Bois trade show in Nantes France 6 weeks ago, I was amazed at how many companies throughout Europe have adopted thermally treated softwood (pine and spruce) and hardwood (mostly ash) for exterior applications instead of chemical treatments or using tropical hardwoods.
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How interesting. How does Thermally treated wood compare to pressure treated wood?
Is thermally treated wood often kiln dried before thermal treatment?
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@Andrew_Gibson The lumber does indeed need to be kiln dried prior to being thermally treated. The lower the moisture content, the faster the thermal treatment process will be. This is an alternative to using chemicals such as those used in pressure treated wood. When exposed to high temperatures, the sugars that are appetizing to insects such as termites are cooked out and therefore improves the termite and rot resistance of the wood and increases its longevity. Europe loves it because it is chemical free, non-toxic and natural.
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Thank you for clarifying! Not to mention it looks like a beautiful product. I’d love to see some in person to get a sense of the look and feel of it. Is it more expensive?
For the US Market all we need to do is throw on some vegan, Non-GMO, and certified organic stickers, then it’ll fly off the shelves!
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