What Is Accoya Timber?
Accoya is a high-performance, sustainable timber that rivals the best tropical hardwoods in durability, stability and aesthetics. Created from fast-growing, responsibly sourced softwood, it’s rapidly become a favourite for premium external joinery—especially windows and doors.
How Is Accoya Timber Made?
Accoya is created through a non-toxic process called acetylation. This chemical process transforms the wood’s structure at a molecular level, significantly improving its durability and resistance to moisture.
Think of it like hardening conkers in vinegar—a simple example of altering organic material to make it more robust. In Accoya’s case, this change involves converting hydroxyl groups in the timber into acetyl groups using acetic anhydride (derived from acetic acid). The result: the timber absorbs far less water, making it highly stable and resistant to decay.
Unlike traditional envelope-treated timbers, Accoya is modified through the entire cross-section. That means there’s no need for on-site chemical preservatives—cut or jointed surfaces are just as durable as the outside.
What Are the Benefits of Accoya for Joinery?
1. Exceptional lifespan
With sensible coating cycles and proper care, Accoya lasts 60+ years above ground and 25+ years in contact with the ground or water. That’s a significant upgrade from standard hardwoods, which typically last around 50 years.
2. Outstanding stability
Because Accoya barely absorbs moisture, it resists swelling, shrinking and warping. This makes it ideal for applications where consistent performance and airtight sealing are key—like sliding and folding doors.
3. Superior paint finish
Its consistent, dense structure sands down beautifully, allowing for a smooth finish. It also holds paint far better than most timbers, reducing the frequency of repainting and improving overall durability. We enhance this further with a grain-filling process before applying our specialist microporous coating, which exceeds the performance of traditional oil-based paints.
4. Low environmental impact
Accoya is a sustainable timber, grown from FSC-certified fast-growing softwood and processed with minimal environmental harm. While the raw material costs more, it more than makes up for this with longevity, performance and sustainability. Thanks to its long lifespan, Accoya is considered a net absorber of CO₂.
For deeper comparisons, explore how Accoya stacks up in moisture-resistant joinery applications, or view our analysis of Accoya vs Red Grandis and Accoya vs Oak.
How Is Accoya Used in Timber Joinery?
At Gowercroft, we use Accoya primarily in external joinery, including:
- Casement and sash windows
- Entrance doors
- French, bi-folding and lift-and-slide doors
- Orangeries and garden rooms
- Conservation and listed property projects
Its low movement, durability and suitability for fine detailing make it especially valuable in heritage work. Our award-winning Heritage Range of vacuum-glazed windows and doors is built using Accoya because it can replicate the appearance of traditional single glazing while delivering modern performance.
Accoya is also our go-to timber when we need to achieve long service life with minimal maintenance, such as in exposed locations or where paint longevity is critical. It features heavily in projects like Saltdean Lido where exceptional weather resistance was essential.
Is Accoya Right for Your Project?
Accoya is not the cheapest option on the market, but it offers serious long-term value—fewer maintenance costs, fewer replacements and better performance. It’s also the most durable timber we offer, outlasting even the hardwood options .
If you’re retrofitting heritage windows, planning a new build, or simply want your timber windows and doors to look great and last longer, Accoya may be your ideal choice. You can also find out how to extend the life of heritage windows to 70+ years with smart design and quality materials like Accoya.
Choosing Sustainable Timber: Our Approach
At Gowercroft, we’ve spent years perfecting our timber selection to offer only two options: Accoya and engineered Red Grandis. We chose these based on rigorous product testing, lifecycle assessments and performance in real-world installations.
To learn more about why we don’t use some popular timbers (and why Accoya made the cut), read our blog on sustainable timber choices.
Talk to Us About Accoya Timber
If you’re considering Accoya for your windows or doors, we’d love to help. Contact us to speak with one of our experts, request a sample, or find out how Accoya could elevate your next project.