Mataverde Therma Wood Hemlock decking works great in all climates


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What is Mataverde ThermaWood Decking?

The ThermaWood process was developed to transform traditional native softwoods into higher performing thermally modified wood decking materials.
The ThermaWood thermal modification process is unique, because it is produced in an autoclave vacuum kiln, at lower temperatures.  Why is this important?
  • ENERGY EFFICIENT PROCESS ": Because the patented ThermaWood autoclave kiln system works under pressure, less energy is used. This means more energy savings and more cost savings to produce a sustainable thermally modified wood decking material for your project. 
  • HIGHER DURABILITY ":  Traditional thermally modified wood processes create a wood decking material  where the Durability is rated as a Class 2 for pine, spruce, hemlock and other softwoods. Durability of wood decking using the ThermaWood process is rated as a Class 1.
  • BETTER STABILITY ": All woods will move (expand and contract) seasonally, based on humidity and moisture content. Especially exterior woods, because they are exposed to more weather elements. Thermally modified woods are FAR more stable than non-modified woods. They expand and contract to a much lower degree. Less movements means better performance.

  • BETTER PERFORMANCE ": The ThermaWood thermal modification process occurs at much lower temperatures due to the use of higher pressure.  This unique method minimizes brittleness, minimizes checks and eliminates most of the mechanical degradation of the wood.  Because of the scientific process employed, the result is a far better performing thermally modified decking material.
  • LESS WASTE ": Because of the lower splitting, checking and brittleness of ThermaWood thermally modified wood decking product, more decking material is usable. The result on the job site is less decking material defect cutting and less waste, and that means a lower overall job cost, faster.
  • LONGER LENGTHS": The vacuum kiln used in processing Mataverde ThermaWood Decking can handle boards up to 20' in length.  This means longer length thermally modified decking boards are available than with other older thermally modified wood processes. 


Mataverde ThermaWood Hemlock Decking 

About ThermaWood Western Hem-Fir (Hemlock) Decking

What is Western Hem-Fir? 

Western Hemlock and Hem-Fir are abundant softwood species throughout the Pacific Northwest.  Because they are so strong, they have been used as a structural lumber product for well over a century.  
Back in the day, non-modified Western Hem-Fir was rarely used for decking and exterior woodworking. Why not? Because, like most other softwoods, non-modified Western Hemlock has lots of sugars, and is therefore not a very durable exterior wood. High sugar content in woods is a food source for both mold and insects. That's why non-treated and non-modified softwoods are susceptible to rot and insect attack.  

What is Thermally Modified Hemlock Decking?

Thermal modification 'cooks' the sugars out of the woods. This alone makes the wood far more resistant to rot, decay and insects. The ThermaWood thermal modification process goes several steps further; its is thermally modified at lower temperatures - under pressure.

  • ThermaWood stays stronger structurally
  • ThermaWood is less brittle
  • ThermaWood is exceptionally durable (Class 1 Durability)


Mataverde Therma Wood Hemlock decking works great in all climates
Mataverde Therma Wood Hem-Fir Decking


Mataverde ThermaWood Hemlock Decking is a high-performance thermally modified decking material. The product is well suited for exterior decking, siding and trim. Because less energy is used in the thermal modification process, the cost is lower, yet the quality, and performance, is higher.

Mataverde ThermaWood Hemlock Decking is available in 5/4 x 6 nominal decking. Lengths are offered 8' through 20' odd and even lengths, random length tallies only. Most of the material is in the 8' through 13' range.  14' through 20' lengths are also offered, in limited quantities, when they are available.


Color and Graining of Mataverde ThermaWood Hem Fir Decking

Before modification, Hem Fir wood is very light toned, nearly whitish, with some light purple tones.  Once the Hemlock is thermally modified, the colors are browner and richer. Mataverde Therma Wood Hemlock Decking looks a lot like Western Red Cedar - except without all the color variations you find in modern cedar.

Here's an example of some typical color variations you will see between Western Hemlock and Thermally Modified Western Hemlock.  As you can see, the thermal modification creates a nice brown appearance.

Mataverde Therma Wood Hemlock

Mataverde ThermaWood Hem Fir decking has warm natural colors and graining


Want to see for yourself?

Would you like to see an actual piece of ThermaWood Hem Fir decking? Request a sample today.


Grading for Mataverde ThermaWood Hem Fir (Hemlock) Decking

Mataverde A & Better Thermally Modified Hemlock is the top grade

With A & Better Hem Fir decking, the top end of the product is selected.  Mataverde A & Better Hemlock has clear  vertical grain and vertical grain appearance boards. Knots are minimal and limited to one side of the board only. There is limited mineral streaking. Mineral streaking is not a defect, it is a part of the characteristics of this species. 

Thermally Modified Hemlock Aye grade 85-15 vertical grain

Thermally modified Hemlock A & Better grade with typical graining and appearance


Mataverde C & Better Thermally Modified Hemlock is the next best grade

The second best upper grade available is C & Better Hemlock.  In this grade you can expect mostly mixed grain and flat sawn Hemlock boards.  In this slightly more rustic grade of Hemlock or Hem Fir decking, you will see a fair amount of mineral streaking and some knots are allowed per board. Most of the knots are small and tight. 

If you don't like the appearance of portions of particular boards, the solution is to defect-cut out that portion, and use the remaining pieces in your project.

Example of thermally  modified Hemlock C+ Better-1

Thermally modified Hemlock C & Better grade with typical graining and appearance


*Pro Tip - Always plan on ordering extra decking to cover your material needs for defect-cutting and trimming your decking boards. This will allow you to use the best boards and the best portions of each decking board to meet you or your clients' needs and expectations. Any extra materials may be saved on site as 'attic stock'. Keeping a small amount of attic stock is a great insurance policy in case they are ever needed in the future.

Installation, Care and Maintenance of Mataverde ThermaWood Decking


Install Mataverde ThermaWood Hemlock Decking at 16" O.C. or less. If installing the decking diagonally, use joist spacing no greater than 12" O.C. Use stainless steel screws or stainless steel nails. Always pre-drill to minimize the potential for splitting or cracking. 


Use a high quality oil based finish with a UV inhibitor for best results. This will help the decking boards season properly and minimize surface checking, especially during the first year.  Water based finishes are not recommended.

Care and Maintenance

An annual cleaning is recommended for best looks and performance. Do not use a pressure washer, bleach or harsh chemicals for cleaning your Mataverde ThermaWood decking.  A biodegradable cleaner, such as Penofin Pro-Tech Cleaner, or similar product, work well. 
After the first year, refinishing your decking is optional. If you would like to maintain the 'like new wood' look, by all means, please refinish your decking. Or if you prefer to allow your decking to naturally weather to a silvery gray patina, that's another, lower maintenance option.

Can't decide how to refinish your decking?
Download the "How Woods Weather Guide" for ideas.

Looking for the best decking options for your project?

Download "The Ultimate Guide to Selecting the Right Decking"

Need some deck design inspiration? Looking for deck ideas?

DOWNLOAD the "Deck Design Ideas Book" today.

61 pages featuring over 150 deck design ideas!