Thermarich Lumber: Thermally Modified Wood

What is Thermarich Lumber?

Thermal modification of wood is a natural process of “cooking” the wood in oxygen-free ovens to temperatures over 400 degrees. Thermally modified wood is an excellent alternative to chemically treated lumber. The thermal modification method changes the wood’s cellular and molecular makeup, removing all the wood’s organic compounds.

This process makes it so the wood can no longer absorb water, reducing the ability of the wood to expand or contract. Which means the wood is highly durable. Removing the ability to absorb water enhances the rot resistance of the wood.
Thermally Modified Wood | Edrich Lumber

Benefits of Thermarich


It cannot be warped or deformed by water due to the natural process that prevents water from being absorbed into the wood.


This process prolongs the life of the wood, which decreases the need to redo your projects by up to 25 years or more!

Free of Chemicals

The thermal modification process uses heat only to cure the wood.

Stages of Production


The temperature increases, removing sap and pitch in the wood. Steam is introduced to the wood making the moisture content go from about 20% to nearly 0%.


This phase is where the water breaks apart from the wood due to the higher temperature heat. Oxygen is completely removed, and the thermal modification process has begun.


Steam is reintroduced to help decrease the wood temperature and maintain dimensional stability. Resulting in a wood moisture content of 4 to 6%

Common Questions & Answers

Kiln Dried Wood is wood that is dried out to a 5%-14% moisture content and does not change its molecular structure.

Pressure Treated Wood uses fungicidal chemical preservatives to protect the wood.

Thermally Modified Wood has a similar kiln drying process. The moisture content is reduced to nearly zero, and the molecular structure of the wood is changed with the introduction of high heat. The results of thermal modification are similar to pressure treated, where it protects against outdoor elements. However, it only uses heat over 400 degrees to produce natural rot-resistant wood without chemicals.
Wood color does change with this process. It gives it a deeper brown hue, resembling more tropical woods and walnut.
This modified wood is commonly used for decking, siding, flooring, wall paneling, ceilings, and accent walls.