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Infographic illustrating the acetylation process used to create Accoya wood. The sequence begins with untreated wood, showing a microscopic view of its cellulose structure with water molecules, naturally occurring acetyl groups, and hydroxyl groups. In the second step, acetylation is depicted by the introduction of acetic anhydride, which reacts with hydroxyl groups to add acetyl groups. This reduces the wood's ability to absorb water. A circular graphic shows acetic anhydride and acetic acid being recovered and reused, with water returned to the ground water system. The final product is Accoya wood, labeled and stacked, shown with a close-up of its stabilized molecular structure featuring added acetyl groups.

Why
Accoya

Redefining The 
World of Wood

At Heritage Sash Wales, we’re proud to manufacture our windows and doors using Accoya®, one of the most advanced and sustainable timbers available today.

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Accoya® wood is the ideal material for traditional timber sash windows, casement windows, doors, and external shutters. It provides outstanding thermal insulation, exceptional dimensional stability, and remarkable durability — performing far beyond even the finest tropical hardwoods.

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Thanks to its unique acetylation process, Accoya® timber resists rot, swelling, and warping, ensuring that your windows and doors open smoothly and look beautiful for decades. It also offers enhanced coating performance, meaning paint and finishes last longer and require less maintenance — saving both time and money.

Still image from a YouTube video titled “The secret inside Accoya: How acetylation works”, showing a scientific animation of molecular structures inside wood. Light-colored and blue spheres, representing molecules, are connected to wooden-looking arms, visually demonstrating the acetylation process used to enhance wood's durability. The red play button overlay indicates it is a playable video thumbnail.

With a 50-year guarantee above ground and 25 years in ground or freshwater, Accoya® offers complete peace of mind that your joinery will stand the test of time, even in the most demanding conditions.

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Made from FSC®-certified, sustainably sourced timber, Accoya® combines the natural beauty of wood with the resilience of modern innovation — delivering a superior, long-lasting product that truly redefines what timber can do.

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Accoya® is wood, but better — the perfect choice for craftsmanship that lasts a lifetime.

Exceptional Durability

Accoya® is guaranteed for 50 years above ground and 25 years in ground or freshwater, making it one of the longest-lasting timber products available. It resists rot, decay, and insect damage, ensuring your windows and doors maintain their strength and beauty for decades.

Dimensional Stability

Unlike conventional timbers, Accoya® doesn’t swell, shrink, or warp with the seasons. This means sashes, casements, and doors continue to open and close effortlessly all year round.

Superior Thermal Performance

Accoya® provides better insulation than most hardwoods and softwoods, helping improve energy efficiency and comfort inside your property.

Low Maintenance

Its unique composition allows paint and coatings to last twice as long, reducing the need for regular maintenance and saving both time and money.

Environmentally Responsible

Accoya® is made from FSC®-certified sustainable sources and modified through a non-toxic acetylation process, ensuring minimal environmental impact while delivering unmatched performance.

Perfect for Heritage and Modern Projects Alike

Combining traditional craftsmanship with cutting-edge innovation, Accoya® allows us to create joinery that meets conservation standards while offering the durability of a 21st-century material.

Logo and tagline for Accoya, a brand of sustainable wood. The image features a stylized triangular symbol in gold, resembling a swirl or abstract leaf, placed to the left of the brand name “accoya” in lowercase gold letters. Beneath the name is the tagline: “Ultra-High Performance Sustainable Wood,” also in gold. The entire design is set against a dark green background, reinforcing themes of sustainability and environmental focus.
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