Accoya vs Standard Timber Windows: Is the Premium Worth It?

Accoya is made from radiata pine, a fast-growing softwood sustainably sourced from FSC-certified plantations in New Zealand. The timber undergoes an acetylation process where it is saturated with acetic anhydride, which permanently modifies the wood's cell structure to dramatically reduce moisture absorption. The result is a timber with Class 1 durability (the highest rating) and exceptional dimensional stability.

For long-term homeowners, yes. While accoya costs 30-60% more upfront than standard softwood, its 50-year guarantee, reduced maintenance frequency (repainting every 10-15 years versus 5-8 years), and exceptional durability mean it often costs less per year of service over its lifetime. The premium is hardest to justify if you plan to sell within 10 years.

Accoya outperforms oak on durability (Class 1 vs Class 2), dimensional stability (70% less movement), weight (much lighter), and machinability (handles like softwood). Oak wins on aesthetics for natural/stained finishes — its dramatic open grain is visually superior. For painted windows, accoya is the better technical choice. For stained windows where grain character matters, oak is unmatched.

Yes. Accoya can be stained or oiled, and its stability means the finish lasts longer than on standard timber. However, accoya has the fine, relatively uniform grain of radiata pine, which is less visually dramatic than oak or sapele under a transparent finish. If the natural beauty of the wood grain is your primary motivation, a hardwood species may be more satisfying aesthetically.

Accoya has among the strongest sustainability credentials of any building material. It is Cradle to Cradle Gold certified, made from FSC-certified fast-growing radiata pine (25-30 year harvest cycle), and the acetylation process produces only vinegar as a by-product. Its 50-year lifespan means fewer replacements over a building's lifetime, reducing cumulative environmental impact.

No. Unlike standard softwood, which requires vacuum-pressure preservative treatment for exterior use, accoya's durability is inherent — the acetylation process permanently modifies the timber's cell structure. No additional preservative treatment is needed, which also means accoya contains no biocides or toxic chemicals.

Exceptionally well. Accoya's resistance to moisture, salt spray, and fungal attack makes it one of the best timbers available for coastal applications. Its dimensional stability means it does not swell, warp, or distort in the high-humidity, salt-laden environment that rapidly degrades standard softwood. Many coastal and marine projects specify accoya for this reason.

Yes. Accoya is a natural timber product that can be machined to match period profiles and detailing. Conservation officers generally accept accoya as a like-for-like timber replacement because it looks, feels, and machines like natural softwood. Its superior durability is an added benefit that conservation officers appreciate, as it reduces the frequency of future maintenance interventions.

Accoya windows need repainting or re-staining every 10-15 years — significantly less frequently than standard timber. The dimensional stability of accoya means paint films crack and flake less, extending finish life. Annual maintenance is limited to checking and clearing drainage channels, lubricating hardware, and cleaning the frames with soapy water. No preservative retreatment is ever needed.

Accoya timber is manufactured exclusively by Accsys Technologies in the Netherlands, but numerous UK window manufacturers use it as a raw material. Leading UK accoya window manufacturers include Mumford & Wood, Bereco, George Barnsdale, Green Building Store, and the Sash Window Workshop. When specifying accoya windows, ensure the manufacturer is purchasing genuine Accsys-certified accoya and not a generic acetylated or modified timber.