Its all in the detail

By significantly extending the service life and improving other performance characteristics of wood without the use of toxins, our process allows specifiers the world over to have greater confidence in and make greater use of timber than would otherwise be the case. Since trees sequester CO2 from the atmosphere, the more we use timber in construction instead of carbon intensive materials such as plastics, concrete and aluminium, the smaller will be our overall contribution to climate change.

Acetylated wood branded as Accoya is wood grown from sustainable sources and modified through a process called acetylation. Essentially it modifies the balance of naturally occurring compounds in wood to improve its durability, stability, and other performance criteria. Acetylated wood is non-toxic, fully recyclable, and contains only naturally occurring wood compounds.

Commonly used in the construction of windows, doors, cladding, decking and structural projects including canal linings, though it can also be used internally where the stability of wood is a key requirement.

Key Applications

Unrivalled Performance, Finish and Sustainability

Unrivalled Performance, Finish and Sustainability

The benefits of Accoya mean that timber projects can now be designed with absolute confidence

From the perspective of performance, the top three attributes of Accoya wood are the most important features:

  • Highly Durable
  • Highly Stable
  • Coatings Performance

Performance testing

Product testing and third-party validation have been undertaken on many different aspects of performance.
Long coating life

All timbers are given a durability class based on test results against key rot species that we encounter in Europe. Class 1 is the best and class 5 the worst. Note that durability classes for natural timbers only relate to the more naturally durable heartwood of the species – any sapwood of any species is rated as durability class 5.

Accoya wood is consistently class 1, better than most UK cladding timbers and has a service life of 60 years.

The superior dimensional stability of acetylated wood is acknowledged by TRADA (Timber Research and Development Association).

In this trial, they compared the relative stability of boards of different timbers in artificially extreme conditions and found almost no cupping in the Accoya wood.


A key benefit of Accoya wood is that the requirement for coatings maintenance is drastically reduced when compared to other timbers. This is illustrated in the photograph taken of a south-facing test rig in Oxfordshire comparing the performance of the same coating system on three different timber substrates after 10 years.

See the results:

After 10 years the Accoya wood boards evidenced their superior long term performance without any form of maintenance.

The exceptional stability and improved UV resistance of Accoya wood lead to extended coating life. TRADA assessment concluded that Accoya wood increased the coating lifetime to first maintenance by a least a factor of 3.


The difference is in the detail


Learn how you can specify Accoya wood products for your next project.

Specification Information
Performance brochure

Tried and tested

Performance brochure

For more information on the performance of Accoya wood versus comparable timber species please see the Accoya Performance Testing Summary here.

Book a CPD presentation

Acetylated Wood: The Optimum Solution for Cladding, Decking, Windows and Doors


Acetylated Wood: A Solution to Many Problems Associated with Timber Cladding

Both Riba approved presentations