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Thermally Modified Wood Siding

Why Thermally Modified Wood?


Thermally modified wood is made by heating it to high temperatures in a pressure-controlled chamber. This all-natural process alters the wood’s chemical and physical properties, reducing its moisture content (less than 9% prior to shipment) and enhancing its durability and stability. As a result, the wood becomes highly resistant to rot, decay, and moisture damage.

Review the independent testing results from the LSU AgCenter to see exactly how thermal modification enhances dimensional stability and rot resistance with our Hemlock and Southern Yellow Pine siding.

View the Testing Data

The Benefits

PERFORMANCE

Enhanced dimensional stability

LONGEVITY

Increased durability and resistance to decay

SUSTAINABILITY

Sourced in North America, Made in USA, Chemical-free

Choose your species, grain pattern, dimensions, color, texture, profile

Species Available Custom Finishes Profiles + Dimensions

Species Available

Wood Species

THERMALLY MODIFIED HEMLOCK
Clear Vertical Grain

A premium-grade substrate crafted for an exceptional refined finish.

Wood Species

THERMALLY MODIFIED SOUTHERN YELLOW PINE
Clear Mixed Grain

Elegant wavy wood grain offering a sophisticated aesthetic at a competitive price.

Custom Finishes

All Montana Timber Products finish options are available for thermally modified wood.  Due to the heat treatment process, color changes and stain interactions with thermally modified wood can be slightly darker.  Please review physical samples before making a final selection.

Available Textures:

SMOOTH

SMOOTH

Sanded face that still has some texture for stain adherence

RAKED

RAKED

Deeply tined wire brush finish

Color Examples (CVG Hemlock):

Dusk

Dusk

Glacier

Glacier

Ash

Ash

Battleship

Battleship

Driftwood

Driftwood

Black

Black

Brown

Brown

Olympic

Olympic

Yukon

Yukon

Cascade

Cascade

Honey Blonde

Honey Blonde

Snowdrift

Snowdrift

Profiles + Dimensions

Available in all standard 1″ nominal siding profiles.

  • 2″ nominal thickness is available in limited quantities for trim and custom profiles upon request.
  • Sold in random 8′–16′ lengths; exact lengths may be available upon request.

CVG Hemlock Siding Width:
4”, 6”, 8”, 10”
SYP Siding Width:
4”, 6”, 8”, 10”
SYP Decking:
5/4" x 6"

Product Stories

Independent Testing Results: Thermally Modified Southern Yellow Pine & Western Hemlock

Posted on: March 5, 2026
A Bellevue Split-Level Reborn

Posted on: November 14, 2025
Modern Lakefront Luxury: Thermally Modified Wood Design in Coeur D'Alene

Posted on: April 14, 2025

Thermally Modified Wood Siding FAQ

Starting price of thermally modified wood offered by MTP is $6.90 per board foot.

Montana Timber Products' thermally modified wood offers several advantages:

  • Sourced and manufactured in North America
  • 20-year limited warranty against rot and decay
  • Chemical-free treatment process
  • Suitable for both exterior and interior applications
  • Available in Clear Vertical Grain (CVG) Hemlock and Southern Yellow Pine substrates.

  • Exceptional durability and longevity
  • Increased resistance to rot, decay, and insects
  • Reduced moisture absorption
  • Minimal warping and cupping
  • Sustainably sourced and environmentally friendly
  • Improved dimensional stability.

  • Thermally modified wood can last 25 years or more
  • It shows enhanced resistance to decay, insects, and fungi
  • The altered cellular structure results in better resistance to moisture and temperature changes.

  • Exterior siding
  • Decking
  • Fencing
  • Architectural elements
  • Interior paneling and ceilings

Yes, the thermal modification process used by Montana Timber Products is completely chemical-free. It relies solely on heat and steam to alter the wood's properties.

Thermally modified wood is not a fire treatment, but rather a specialized wood product that undergoes a high-temperature heat treatment process. This process transforms the wood's natural cellular structure, enhancing its durability, stability, and performance without using chemical treatments.

Why Montana Timber Products?

natural wood

Embrace Authentic Beauty: We take pride in offering a stunning selection of sustainably farmed species, including Douglas Fir, Cedar, Southern Yellow Pine, and Hemlock ideal for architectural cladding and timbers. Elevate your space with the warmth and elegance of natural wood.

Custom milled

Tailored to Perfection: We can meet your exact design needs our product offerings range from custom siding and trim to large post and beam applications. MTP is the industry leader in specialty lumber.

prefinished

Ready for Immediate Use: Save on time and quality. Our durable, professional-grade Seal-Once finish, applied in our controlled facility, offers superior UV and water protection. Enjoy our premium finish options without the hassle of on-site finishing.

direct to customer

Simplified Purchasing Experience: 
We streamline the buying process and eliminate unnecessary middlemen. This direct relationship ensures that your specific needs are met with efficiency and care. Delivered directly to your jobsite.

Questions?
We are here to help.

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