Thermally Modified Wood
What is Thermally Modified Wood?
Thermally Modified wood is wood that has undergone a specialized process in which it is heated with steam to temperatures of approximately 400–410°F. This process transforms the wood at the molecular level, creating a highly durable material that is ideal for outdoor applications.
During the modification process, the wood's cell walls become permanently stabilized, making the wood much more resistant to water absorption than untreated wood.
One of the greatest advantages of Thermally Modified wood is its exceptional durability, providing an outdoor lifespan of 25 years or more. The process uses only heat and steam, without chemicals or preservatives, making it an environmentally friendly choice. Americana ™ Thermally Modified wood is sustainably sourced from responsibly managed Pennsylvania farmland, offering a renewable and environmentally conscious building material.
Siding & Rainscreen
Our Thermally Modified wood products are available in Oak, Poplar, and Ash. We offer a variety of siding profiles, allowing you to customize the look to match your design preferences. Whether you prefer a classic horizontal installation or a modern vertical application, our siding provides the flexibility to achieve your desired aesthetic.
Our Thermally Modified Hardwood Siding & Rainscreen is available in lengths ranging from 6 to 12 feet in precise 1-foot increments, making it easy to find the right fit for your project. Customers love the product for both residential and commercial applications.
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Decking
Americana™ Thermally modified wood is a great choice for decking projects due to its high durability, practicality and aesthetic appeal. Our decking is effortless to install and will add long lasting beauty to your outdoor spaces. We offer Oak, Ash and Poplar giving you the option to choose the wood that best suits your design vision.
Our decking features symmetrical profiles compatible with standard hidden fasteners, allowing you to choose your preferred board face. Innovative structural end joints enable flooring-style installation with joints placed between joists, reducing waste and speeding up installation.
| Nominal Size | Net Size | Length | Profiles | Species | Grade | Recommended Clips |
|---|---|---|---|---|---|---|
| 1 x 6 | 0.75" x 5.50" | 6'-12' Long | Groove & Groove / Eased 4 Edge / With or Without Structural End Match | Thermally Modified Oak or Thermally Modified Ash | Prime Grade | DeckWise® / ThermoClip™ |
| 5/4 x 6 | 1.00" x 5.50" | 6'-12' Long | Groove & Groove / Eased 4 Edge / With or Without Structural End Match | Thermally Modified Oak or Thermally Modified Ash | Prime Grade | DeckWise® / ThermoClip™ |
Species
Oak: Northern Red Oak is known for its strength, durability, and distinctive grain pattern. Native to the eastern United States, it offers timeless beauty and exceptional performance for exterior applications when thermally modified.
Poplar: Tulip Poplar is one of North America's tallest hardwoods and is valued for its versatility and stability. Thermally modified Poplar provides a lightweight, durable option with a clean, contemporary appearance.
Ash: American White Ash is known for its outstanding strength, flexibility, and smooth grain. Long used for baseball bats, hockey sticks, and fine furniture, thermally modified Ash delivers exceptional durability with a refined, modern look.
Installation Tips
- Use Stainless Steel Fasteners: Always use high-grade stainless steel screws or nails to prevent rust, corrosion, and staining over time.
- Pre-Drill Fastener Holes: Thermally Modified Hardwood should always be pre-drilled before installing screws or nails to help ensure a clean, secure installation.
- Maintain Proper Ventilation: Install siding as a rainscreen system with adequate airflow behind the boards to promote drainage and long-term performance.
- Protect the Finish: To maintain the wood's rich color, apply a penetrating UV protectant such as Cutek Extreme. Reapply every six months during the first few years, or allow the wood to naturally weather to an attractive silver-gray patina.
Frequently Asked Questions
What is thermally modified wood?
Thermally modified wood is natural hardwood that has been heated with steam to approximately 400–410°F. This specialized process changes the wood at the molecular level, stabilizing its cell structure and reducing its ability to absorb moisture. The result is a durable, dimensionally stable wood product that is well suited for outdoor applications such as decking, siding, and rainscreen systems.
Are chemicals used to make thermally modified wood?
No. Americana™ Thermally Modified Wood is produced using only heat, steam, and time. No chemical preservatives are added during the modification process, making it a natural and environmentally responsible alternative to chemically treated lumber.
How long does thermally modified wood last outdoors?
Americana™ Thermally Modified Hardwood has a Class 1 durability rating and an expected outdoor lifespan of 25 years or more. Proper installation, ventilation, care, and environmental conditions can all contribute to the product’s long-term performance.
Does thermally modified wood need to be pre-drilled?
Yes. Thermally modified hardwood should be pre-drilled before installing screws or nails. Pre-drilling helps prevent splitting and creates a cleaner, more secure installation.
Evergreen Forest Products also recommends using high-grade stainless steel fasteners. Stainless steel helps prevent rust, corrosion, oxidation stains, and discoloration around the fastener locations.
Can thermally modified wood check or crack?
As with any natural wood product, thermally modified boards may develop small, superficial checks as the wood adjusts to the moisture conditions of its environment. Minor surface checking is a natural characteristic of real wood and does not necessarily indicate a problem with the product.
Applying a penetrating wood oil or protectant, such as Cutek Extreme, may help minimize checking while protecting the appearance of the wood.
What maintenance does thermally modified wood require?
Thermally modified wood is relatively low maintenance. Occasional cleaning can help remove dirt, pollen, mildew, and other surface buildup.
You can choose between two appearance options:
* Apply a penetrating UV protectant to help preserve the wood’s warm, rich color.
* Leave the wood untreated and allow it to naturally weather to an attractive silver-gray patina.
When maintaining the original color, follow the finish manufacturer’s application instructions. During the first few years, the UV protectant may need to be reapplied approximately every six months, depending on sun exposure, weather conditions, and the application.
How much spacing is required between thermally modified deck boards?
Thermally modified deck boards should be installed with a minimum spacing of ¼ inch between boards. The decking should also be installed at least 12 inches above the ground with proper ventilation underneath.
Adequate spacing and airflow allow water to drain, help moisture evaporate, and support the long-term performance of the decking. Always follow the current installation guide and applicable building requirements for your specific project.
Is thermally modified wood sustainably sourced?
Yes. Americana™ Thermally Modified Hardwood is produced from natural Oak, Ash, and Poplar sourced from responsibly managed forests in Pennsylvania. The thermal modification process does not require chemical preservatives, plastics, or synthetic additives.
FSC-certified options may also be available. Contact Evergreen Forest Products to discuss current species, profiles, certifications, and product availability for your project.
