Thermarich: the Best Alternative to Pressure Treated Wood

treated wood | Edirch Lumber

Trying to decide what lumber to use for your new deck can be exhausting. With many options on the market, Thermarich is the latest and most reliable option for your next project. Thermarich is our thermally modified wood version and an excellent alternative to pressure-treated wood. Sustainability, affordability, appearance, and environmental considerations are all things that should be talked about before you choose what is best for your home. Before we compare the two, let’s review the creation process of thermally modified and pressure-treated lumber. 

The Thermal Modification Process

This process uses a kiln that increases the temperature, removing sap and pitch in the wood. After steam is introduced to the wood, the moisture content goes from about 20% to nearly 0%. The water breaks apart from the wood in the next phase due to the high-temperature heat. Oxygen is completely removed, and the thermal modification process has begun. In the final step, steam is reintroduced to help decrease the wood temperature and maintain dimensional stability. The result is a wood moisture content of 4 to 6%. 

The Pressure Treated Process 

This process takes the lumber and places it in a pressure chamber. The pressure chamber is then flooded with liquid chemicals, and the pressure is increased. This helps the chemicals spread throughout the wood. The lumber is removed from the pressure chamber and sits on a drip pad until it dries completely. 

Let’s Compare! 


Thermally Modified wood is expected to last 25 years or more. It is resistant to moisture and humidity, resulting in the wood’s resistance to warp, twist, or expand. Due to its lack of moisture, it is also more resistant to wood-destroying fungi and insects. Thermally modified wood is less likely to splinter than pressure-treated wood, making it a safer option for your family and pets. Pressure-treated wood is expected to last 10 to 20 years. The durability of the pressure-treated lumber depends on the chemicals used to treat it. Fungicidal pesticides are commonly used to prevent the spread of fungi in the wood. 


Pressure-treated wood, on average, is $6-8 per square foot, while thermally modified wood is around $8-10 per square foot. While thermally modified wood is a bit more expensive, the lifespan makes up for the price. 


Thermally modified wood will have a darker tone due to its lack of moisture, giving it a more exotic color. Color will also vary based on cook time and tree species used. However, like most woods, the color will fade and turn more gray if left untreated. UV protective wood oils are an environmentally friendly way to keep the rich color of the thermally modified wood.

Most pressure-treated wood is lighter in color and comes out with a more green tint due to the copper in the treatment. The green will fade over time, giving you more of the brown shade, but it will then turn gray due to sunlight exposure. Wood stains are commonly used to keep the pressure-treated wood from graying. 

Environment considerations 

Thermally modified wood is treated with heat and steam only to change the cellular structure of the wood. No chemicals are involved in this process, making it the safer option for the environment. 

Pressure-treated wood is impregnated with chromium, copper, and arsenic chemicals. These chemicals can harm your soil, impacting your plant’s life expectancy and quality. Chromium can negatively affect your plant’s metabolic activity and reduce vegetable and grain quality when absorbed into the soil. At the same time, arsenic can stunt growth in plants and ultimately cause them to die. Then there is copper, which, in excess amounts, can make it so only a select few plants can survive. 

Edrich Lumber’s Thermarich is a must! 

Thermarich is the best all-around option for your next home project. It is an excellent option for that new deck you’ve been dreaming of and makes the perfect accent wall to elevate your home. Unlike pressure-treated wood, Thermarich is safe to use indoors. Need some inspiration? Check out some of the ways our customers have used Thermarich or contact us today!