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We have gone to contract for the finish carpentry portion of the project and are hopefully working out the final details of the 5th level exterior deck scope today. I appreciate the clarity you have provided thus far, I wish everyone could be so detailed!

Christopher Martin
Estimating, Master Millwork

Thermally Modified Ash

HDG is proud to be a Thermory® dealer and include thermally modified ash among its durable, eco-friendly wood products. Thermally modified ash is ideal for those who appreciate a distinguished exterior eco-friendly hardwood. Thermal modification gives wood a beautiful rich color and aesthetic appeal. It makes wood more durable, stable, and resistant to the environment, while retaining the warmth of real wood.

Thermory products are unrivaled in environmental responsibility. Thermory is the industry leader in thermal modification, and invests in the latest thermo-treatment technology, manufacturing and installation techniques. Thermory has developed an environmentally responsible solid hardwood product that delivers luxury and rivals the finest tropical woods.

  • 100% harvested from sustainable, renewable, North American & European forests
  • Chemical-free process
  • Responsible, yet sophisticated alternative to exotics

Thermory Benefits

Color & Beauty

  • Exotic brown color through full thickness
  • Naturally ages to a rich platinum gray
  • Preserve original exotic brown with UV protectant oil
  • Variations in color are natural


  • Removes wood sugars to give 25+ years of resistance to rot & decay (Class 1 durability)
  • Fire-rated & Calfire-WUI approved
  • Thermory 5/4″ Ash Decking is Class-A Fire Rated for use in roof-deck assemblies


  • 7X less likely to warp, check, bow, cup, twist, expand, or contract
  • Exceeds stability standards and relative humidity ASTM testing


  • Easy on tooling
  • Lighter weight
  • Non-toxic dust
  • Smooth & splinter-free
  • Machines beautifully
  • Disperses heat (No hot feet!)


Thermally modified wood was the secret of Northern seafarers who used the process to render their ships resistant to the corrosive effect of salty waters. This same ancient process has been modernized to bring this unique finishing into modern homes and public spaces. Thermally modified ash products have high resistance to heat, water, fungus and mould. This makes the wood usable in places where most other natural materials would fail – outdoors, high-moisture areas, saunas and on top of heated floors. Thermory decking and cladding is used by architects, designers, and building professionals for decking, soffits, siding, wall cladding, facades, flooring, swimming pool surrounds, sun decks, terraces, rooftop decks, and green roofs in 50 countries. Use Thermory decking with Buzon BC Series pedestals to design raised terraces and decking applications that slope to drain while maintaining a perfectly level surface for furniture, people, and other objects.

Thermal Modification Facts


  • Process uses only heat and steam (no chemicals)
  • Heated to approx. 400°F
  • Equalized at 6% moisture content
  • Adjusts cell structure


  • Chemical-free thermal modification process
  • Sourced from well-managed American & European forests
  • No rainforest wood

North American White Ash

  • Harder than Red Oak
  • Used to make baseball bats

Proven Technology

  • Perfected European thermo-treatment technology
  • In use for over 17 years worldwide
  • Over 100 million square feet in existing applications
Thermally Modified Ash 1 x 6 Cladding in Hospital Facade - HDG Building Materials
Thermally Modified Ash 1 x 6 Cladding in Hospital Facade - HDG Building Materials

Cladding Sizes:

  • 1 x 6 (.79” x 5.9”) Tongue & Groove Profile
  • 1 x 6 (.79” x 5.6”) C20 Profile w/channel groove
  • 1 x 6 (.79” x 5.6”) C23J Profile w/ channel groove — made for PaCS (Press and Click Strip) System
  • 1 x 4 (.79” x 3.5”) Tongue & Groove Profile
Thermory Ash-Cladding and Decking - HDG Building Materials

Decking Sizes:

  • 1 x 4 (.79” x 3.7”)
  • 1 x 6 (.79” x 5.2”) STD
  • 1 x 6 (.79” x 5.9”) MAX
  • 5/4 x 4 (1.02” x 3.5”)
  • 5/4 x 6 (1.02” x 5.7”) MAX
  • 5/4 x 6 Slim (for EB-TY Clips) 5/4 x 6 (1.02” x 5.1”) STD
  • 5/4 x 8 (1.02” x 7.3”) Wide Spruce Decking

Custom Profiles Available

Custom fabricated sizes can be created from standard sizes to meet your project’s requirements. Below the 2×2 D4 shown is a custom profile that is produced from 2×4 (or 2×6 strips).  The “D4” profile simply means S4S with 4 eased edges.  We can take a 2×4 strip and rip it in half, or take a 2×6 strip and rip it into 3 pieces, and then re-profile the ripped strips to make a 2×2 (1.65” x 1.65”).  2×2 D4 is shown below.

HDG Thermo Ash Profile 2x4 - Dealer HDG Building Materials
Making Custom Thermory Profile - 2x4 Ripped to Make 2x2 D4 Thermo-Ash - Dealer HDG Building Materials
Profiled Edges on Ripped 2x4 Thermory to Make Custom 2x2 D4 Thermo-Ash Profile - Dealer HDG Building Materials

See Thermory decking and cladding project that uses this 2×2 D4 Thermo-ash custom profile.

Pool House Cladding Application with Thermally Modified Ash - HDG Building Materials

Cladding Technical Specs:

Thermory PaCS™ System Installation (Press and Click Strip)

  • Cladding boards are pre-grooved for PaCS™ System
  • Incomparably fast installation

Joint End Matched (JEM) Joints

  • NOT required to rest on furring strips or PaCS™ Strip
  • Reduced waste (98% Yield)
  • Accelerated installation speed (less cutting/measuring)

Traditional Installation

  • Stainless Steel Sihga Screws (pre-drilling not required)


  • Minimal (naturally ages to a rich platinum gray)
  • Maintain exotic brown with standard UV protectant oil


  • Clear, straight and flat

Decking Technical Specs:

Thermory Hidden Clip System Installation

  • Stainless steel hardware
  • Perfect spacing and quick installation
  • Machined side grooves for fasteners

Traditional Installation

  • Face screw with Stainless Steel Sihga Screws** (pre-drilling not required)


  • Minimal (naturally ages to a rich platinum gray)
  • Use UV protectant oil to maintain exotic brown

Grade/Standard Sizes*

  • Clear, straight and flat
  • Grooved for hidden fasteners or non-grooved
  • 5 -7% wider than standard, more coverage per lineal foot

Help and Resources

Do you have a project you require a solution for, or need more product details? Call 503.360.9551 or Click.

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