What is thermally modified wood?

Thermally modified wood (Thermowood) is lumber heated to 180-215 degrees Celsius in a controlled oxygen-free environment. This permanently alters the wood's cell structure, dramatically improving rot resistance and dimensional stability without chemicals.

Is Thermowood as durable as cedar?

Thermowood achieves comparable or better rot resistance than cedar through its thermal modification process. However, the treatment makes wood more brittle, so impact resistance is lower than cedar.

Can you stain or paint Thermowood?

Yes, Thermowood accepts stains, oils, and paints well. Many homeowners apply UV-protective oil to maintain its rich brown color, similar to maintaining exotic hardwood decking.

Thermowood (Thermally Modified) vs Cedar wood grain comparison

building materials

Thermowood vs Cedar Cladding: Modified vs Natural Wood (2026)

Prepared by Lumberama's Wood Comparison Team

|Last updated July 1, 2026|Sources & methodology

Thermowood (thermally modified timber) is a growing alternative to traditional cedar for exterior cladding. The thermal modification process uses heat to improve rot resistance without chemicals, creating an intriguing competitor to cedar's natural durability. This comparison examines both options for modern exterior applications.

Thermowood (Thermally Modified)

Cedar

Key Takeaways

Thermowood (thermally modified timber) is a growing alternative to traditional cedar for exterior cladding.
The thermal modification process uses heat to improve rot resistance without chemicals, creating an intriguing competitor to cedar's natural durability.
This comparison examines both options for modern exterior applications.
Both are excellent chemical-free cladding options with similar lifespans.
Thermowood offers better stability and sustainability; cedar offers proven performance and easier maintenance.

Property	Thermowood (Thermally Modified)	Cedar
Price/Sq Ft	$5-$10	$6-$12
Rot Resistance	Very good - heat treated	Good - natural oils
Stability	Excellent - reduced moisture uptake	Good
Chemical Treatment	None - heat only	None - natural
Color	Rich chocolate brown	Warm reddish-brown
Sustainability	Excellent - domestic softwoods	Good
Lifespan	20-30 years	20-30 years

Thermowood (Thermally Modified)

Pros

Chemical-free rot resistance, Made from abundant domestic species, Superior dimensional stability, Consistent dark color

Cons

More brittle than untreated wood, Limited availability, Newer technology with less track record, Can be harder to source

Cedar

Pros

Proven centuries of outdoor use, Natural beauty and aroma, Widely available, Easy to work with and repair

Cons

Grays without maintenance, Sapwood has poor durability, Price increasing due to demand, Limited color range

Best Use Cases

Choose Thermowood for a chemical-free, dimensionally stable cladding option with a rich dark color, especially when using sustainably sourced domestic species. Choose cedar for proven natural beauty with established supply chains and repair techniques.

Verdict

Both are excellent chemical-free cladding options with similar lifespans. Thermowood offers better stability and sustainability; cedar offers proven performance and easier maintenance. Thermowood is the emerging choice for eco-conscious builders.