As the first company to produce acetylated wood on a commercial scale, Accoya® is leading the charge in providing durable and dimensionally stable wood for a variety of applications. In the acetylation process, softwood is essentially turned into a hardwood through the introduction of a non-toxic vinegar-like solution, creating a new type of wood that is durable all the way through the board, not just on the surface. In practice, this allows for a wood product that is significantly protected against the elements, making it perfect for installation in exterior environments where a standard sealed wood product would fail after only a short amount of time.

At Hewn, we build upon the extraordinary properties of Accoya® wood by applying our proprietary color and finish techniques to create beautiful, unique, and long-lasting wood products, suitable for a variety of applications, and customizable for the specific needs of your project.


Endless Versatility

The uniquely durable properties of Accoya®, created using an all-natural process, allow the wood to be utilized for a variety of purposes. Our sales representatives can customize your order to fit your precise needs and use-case scenarios.

Exterior Siding

Sealed for optimal protection against the elements

Interior Paneling

Durable enough for high-traffic commercial areas


Insect and rot resistance in a real-wood product


Widths: 1×6, 1×8
Thickness: 3/4″, 7/8″, 1½”


Greater than 9 rating per AWPA E7

Moisture Content

3-5 % at 65% relative humidity, 20°C

Density and Spread

65% RH, 20°C, Average 32 pcf, Range 27 to 37 pcf

Fire Rating

Class C (ASTM E84) and D (EN14915)

Thermal Conductivity

ASTM C177, = 0.102 – 0.120 W/m∙K

Janka Hardness

ASTM E143, Tangential = 972 psi, End Grain = 1,484 psi


Approved by WDMA as compliant with WDMA I.S. 4. Certified as compliant with Cradle-To-Cradle with Platinum Level Material Health Certificate.

Acetylated wood, at-scale.

Acetylation has been studied and practiced in the wood industry for more than 70 years. The process, by which wood is effectively “pickled” in an all-natural vinegar-like substance, was once considered impossible to produce in large quantities. With Accoya®, however, these barriers have been eliminated, and this durable real-wood non-toxic product can be produced and purchased at-scale. 

And with Hewn’s expertise in coloring and finishing, Accoya® can be elevated to the next level, creating a timeless look and feel perfect for your next commercial or residential project.


Standard Milling Profiles

5/4×6 Clear Square S4S
Actual Dimensions: 3/4″ x 5 1/2″
Lengths: 8′, 10′, 12′, 14′, 16′

1×6 Clear 90 Degree Shiplap
Face: 5″
Gap: Tight, 1/4″, 3/8″, 1/2″
Actual Dimensions: 3/4″ x 5 1/2″
Lengths: 8′, 10′, 12′, 14′, 16′

1×6 Clear T&G w/Nickel Gap
Face: 5 1/4″
Gap: Tight, 1/16″, 1/8″, 3/16″, 1/4″
Actual Dimensions: 3/4″ x 5 1/2″
Lengths: 8′, 10′, 12′, 14′, 16′

* Some milling profiles may be unavailable on certain finishes, including (but not limited to) our Heavy Char options. Please contact our sales representatives for additional information and alternative options.