What is Thermally Modified Wood?

What is Thermally Modified Wood?

Categories: Inspiration

Thermally modified wood is the next generation of wood cladding. It has been around since the 1990s when it was developed in Europe as an alternative to tropical hardwoods. It is now taking off in the U.S., as it continues to outperform untreated wood. Thermal modification is an all-natural process that incorporates both heat and steam to permanently alter the wood fiber at a cellular level.

 UFP-Edge Thermally Modified Wood Cladding Timber Ridge and Natural Modern Forest Home
This modern home features Thermally Modified Wood Cladding in Natural and Timber Ridge. 

The Thermal Modification Process 

Thermally Modified Wood Collection heat and steam preservation process graphic
Using just heat and steam, the wood’s physical and chemical makeup is changed to create thermally modified wood.

The thermal modification process begins by heating the wood to 320 degrees in an oxygen-free environment. To prevent wood shrinkage, steam is infused to retain some moisture.

As the heat rises, the sugars in the wood are removed. This reduces the wood’s moisture content to a very low level and makes it less susceptible to insects and decay. It also makes the wood less vulnerable to seasonal expansion and contraction cycles. In a sense, the process "petrifies" the wood so it becomes more stable. 

Not only does the wood’s composition change throughout the process, but the wood’s appearance changes to a deeper color. You won't be able to tell a difference with our prestained colors, but our natural options are much richer in color than other brite wood options. 

The Benefits of Thermally Modified Wood 

Exterior wood siding installation
The low moisture content of thermally modified wood makes it lightweight and easy to cut and nail. 

  1.  Dimensionally Stable

    Thermally modified lumber has gained popularity because of its beneficial properties. It’s dimensionally stable and proven to be more durable and less likely to warp than its wood counterpart. Our Thermally Modified Wood Collection has a Class 1 durability rating, which is the highest out of four timber durability ratings.
  2. Rot Resistant

    Since the thermal modification process "cooks" out the sugars in the wood, it makes the wood naturally rot resistant. To help ease any concerns, our Thermally Modified Wood Collection has a 20-yr limited warranty on the substrate

  3. Lightweight and End-matched 

    As a result of its low moisture content, it is lighter in weight than typical wood, which makes it easier to move around, cut and install. On lengths longer than 8 feet, boards come end-matched. This means that there is a tongue and groove on the ends of the boards so that they can easily be installed end to end. End-matched boards remove the need for installing directly to a stud and create less waste on the job site.

     Gif shows two end-matched boards coming together

  4. Eco-friendly

    The thermal modification process is made with only heat and steam––no chemicals that could leach into the environment.

    Modern rustic house with backcountry thermally modified wood collection accents
    This barndominium features Thermally Modified Wood Collection in Back Country.

Prefinished and Natural Color Options

Our Thermally Modified Wood Collection brings added value to the home with its on-trend prefinished color offerings. No need to delay construction time with on-site painting. Each board comes prefinished in a variety of on-trend colors and in a Natural (clear coat) finish so you can achieve the look you want in less the time.

Thermally Modified Wood Cladding color swatches and product names

The prefinished (painted) cladding greatly reduces the variables weather may have on the finish and eliminates the varying moisture levels that adversely affect unfinished siding products stored outdoors. By keeping products indoors and inspecting them prior to finish, we ensure the most consistent and highest quality finish available.

View the entire collection of natural and prefinished colors.

The Thermally Modified Wood Collection provides beautiful curb appeal for years to come.

This modern beachfront home features Thermally Modified Wood Collection in Timber Ridge and Natural. 

Learn more about our Thermally Modified Wood Collection


READY TO START YOUR PROJECT? FIND where to buy online or at a retailer near you. 


A Guide to Understanding Common Wood Siding Patterns
What Are the Differences Between MDF and Real Wood?
Do You Need Drywall to Install Shiplap? 

Thermally Modified Modern house with edge bug logo overlay