Wood Siding FAQS

• How is Accoya wood made?

  The Accoya production process does not weaken the original wood – in fact, its hardness is slightly improved and its bending strength uncompromised. Indeed, no modification process exists which offers the performance benefits and retained physical properties of Accoya.

  The process alters the cell structure of wood, improving its technical properties and making it much stronger and more durable. Unmodified wood contains ‘free hydroxyl groups’ that absorb and release water as weather conditions change.

  This makes standard wood susceptible to expansion and contraction, particularly when used outdoors for applications such as siding, window and door frames.

  The expansion and contraction of wood often leads to splitting and rotting, impacting on the service life of wood. Hydrogen, oxygen and carbon chemicals (called acetyl groups) are created within wood after the acetylation process, changing the structure of existing free hydroxyl groups (hydrogen and oxygen). Each of these chemicals is present naturally in all woods, with acetyl created independently from acetic acid, i.e. vinegar. The process is ‘green’ meaning that the acetylation process takes effect using nothing that doesn’t occur in wood naturally.

  Read more in our blog: What is Acetylation?

• How environmentally friendly is Accoya wood?

  Accoya wood is non-toxic and 100% recyclable. By significantly enhancing the durability and dimensional stability of fast growing, abundantly available certified wood species, Accoya wood provides compelling environmental advantages over scarce slow growing hardwoods, woods treated with toxic chemicals, and non-renewable carbon-intensive materials such as plastics, steel and concrete.

  The environmental impact of Accoya can be assessed at all stages of its life cycle, from cradle to grave. At the production stage, only abundantly available, and often fast growing source species such as Radiata pine, are used to create Accoya, safeguarding a consistent supply and preventing deforestation of tropical forests. Accoya is made from legally harvested wood from well managed sustainable sources including FSC®, PEFC and other regionally certified woods.

  The Accoya wood manufacturing process is non-toxic and adds nothing to the wood that does not already naturally occur in it. The Accoya production facility meets highest requirements with respect to health, safety and the environment and powered for over 50% by renewable energy. Accoya remains CO2 negative over the full life cycle; therefore an environmental friendly substitute for tropical hardwood and materials from non-renewable resources.

  Accoya has acquired several quality certifications (e.g. KOMO, RAL, WDMA, etc) and is warranted against fungal decay for at least 50 years above ground and 25 years in ground. Outstanding dimensional stability and improved hardness results in lower maintenance frequency (lower costs) and therefore less coating use and waste over the product’s lifetime. Additionally, Accoya’s superior thermal insulation provides energy conservation advantages when used in applications such as window frames and doors. Accoya wood is fully reusable and recyclable. Reuse is recommended but Accoya may be safely incinerated for bio-energy or composted to close the loop of the carbon cycle. Indeed, in the Cradle to Cradle® philosophy, for which it holds the prestigious Gold-level certification, Accoya wood is understood to be non-toxic and 100% biodegradable.

• Is Accoya wood siding suitable for all climates?

  Yes. Accoya wood siding stands out for its remarkable performance in every climate - from humid coastlines to dry deserts and regions with harsh winters. Unlike most traditional timber siding, which often depends on chemical preservatives to provide protection, Accoya wood siding benefits from an advanced modification process at the cellular level. Instead of coating the surface or only using thermal modification, the ‘acetylation’ process enhances the wood’s natural structure throughout, making it highly resistant to moisture, swelling, and shrinking.

  This means that even in environments with significant temperature fluctuations or persistent humidity, Accoya wood siding remains remarkably stable.

• How does Accoya wood siding compare to cedar siding?

  Accoya wood siding offers superior durability and stability compared to traditional cedar. While cedar is valued for its natural appearance, it can be prone to warping, cracking, and damage from insects over time. Accoya’s advanced modification process, acetylation, transforms the wood siding’s cellular structure, making it far more resistant to these common issues. This results in a wood siding product that holds its shape better, resists rot and termite attacks while being non-toxic and requiring less maintenance.

  Accoya wood provides a longer-lasting and more reliable exterior wood siding.

• What is the warranty on Accoya wood siding?

  Accoya offers an industry-leading 50-year warranty for above-ground use. This isn’t just a promise, the warranty is backed by decades of scientific research into acetylated wood, the process that makes Accoya so durable. Real-world testing demonstrates a service life of up to 60 years, highlighting Accoya’s significantly higher durability compared to traditional options. Over the years, independent tests and long-term trials have shown just how well Accoya holds up against rot, insects, and the elements.

  Respected organizations like Building Research Establishment (BRE) and TRADA fully support the durability claims of Accoya wood. When choosing wood siding from Accoya, you’re getting not only a beautiful and sustainable product but also the reassurance that it will perform for decades to come.