What is Thermally Modified Wood?

Rise
3 min readJun 4, 2020

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It seems like every new decking material is trying to imitate the look of natural wood. There’s nothing like that natural aesthetic, which is why we’re always trying to find that perfect wood product that is simultaneously beautiful, durable, and healthy for our families and the environment.

ThermalWood Canada

The Rise team first wrote an article about thermally modified wood back in August 2019, but our love affair started when we connected withBob Lennon of Thermalwood Canada at the 2020 International Builders’ Show in Las Vegas. “It took a Las Vegas conference for us to connect,” Bob said while laughing. Thermalwood is based in Miramichi, New Brunswick which is just a few hours north of the Rise headquarters.

Thermalwood is one of the three leading manufactures or thermally modified wood in North America (aka thermally treated wood or torrefied wood). The technology started in Europe back in the 90s but it’s still a relatively unknown product on our side of the pond. That is exactly the kind of fledgling building product we love to sink our teeth into.

Thermally modified wood is a high-quality building product that is superheated to 200 degrees celsius to modify the structure of the wood. The process imbues the wood with a natural resistance to moisture and all the nasty things that come with it: insects, mold, cracking, and warping.

ThermalWood Canada

This chemical-free process makes thermally modified wood a “green” alternative to the more common pressure-treated lumber. Treated lumber for exterior projects is known to contain preservatives like Penta, CCA, ACA, and FCAP, and more. Some of the chemicals are known to increase cancer risk, so when they seep into the surrounding soil it can put children and animals at risk.

Thermally modified wood’s natural moisture resistance makes it a smart option for exterior applications like siding and decking. Some manufacturers offer warranties on decay for 25 years for a deck and up to 60 years for siding. The wood is also used for interior projects like flooring, wall paneling, and even fine musical instruments.

ThermalWood Canada

No building product is perfect, however. Here are the main pros and cons:

What are the main advantages of thermally modified wood?

  • Resistant to moisture, insects, mold, cracking, and warping
  • The process brings out a deep color and rich texture
  • It’s free of chemicals
  • Gives a practical use to a variety of tree species

What are the main disadvantages of thermally modified wood?

  • It has reduced bending strength, so it isn’t a good option for load-bearing projects
  • It’s about twice the price of pressure-treated lumber
  • The wood’s color fades over time, so it requires re-sealing at least once per year

So, what do you think of thermally modified wood? Would you use it for your next lumber project?

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Rise
Rise

Written by Rise

Turn any home improvement project into a sustainable one. Get know-how and connections on sustainable and money-saving options for your new home or reno.

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