What is Accoya?
- Accoya is a brand name for a high-performance modified wood product.
- It is made from fast-growing, sustainably-sourced softwood (specifically Pinus radiata a.k.a. radiata pine).
- The key process is acetylation: wood is treated so that the wood’s free hydroxyl (-OH) groups – which attract water – are converted into acetyl groups, reducing the wood’s ability to absorb water.
- Because of this modification, Accoya offers much greater dimensional stability, durability and environmental credentials compared to many untreated or conventionally treated timbers.Key Properties & BenefitsHere are some of the standout features:Durability: Accoya is rated Class 1 in durability (the highest grade) and comes with warranties of ~50-years for above ground use and ~25-years for in-ground/freshwater use.Dimensional Stability: Swelling and shrinking are substantially reduced compared to regular softwoods. It helps maintain straightness, flatness, and reduces warping/cupping.Environmental / Sustainability: Because it uses fast-growing softwoods, is non-toxic, 100% recyclable and has strong green credentials.Workability & Finish: The acetylation process does not weaken the wood—in fact the performance (e.g., hardness) can be improved—so it retains good machinability and is compatible with standard coatings and finishes.Coatings & Maintenance: Because of the stability, coatings last longer. For example, some trials indicate a 3-4x increase in coating life before maintenance is needed.Applications
- Accoya is used for a wide variety of applications, particularly where durability, weather-exposure and stability are critical:
- Windows & doors (especially in demanding climates)
- Exterior cladding and siding
- Decking and outdoor flooring
- Structural or semi-structural uses: bridges, water exposure, canal linings etc.
- Interior where moisture stability is important (though many use it externally)


