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Sustainably sourced, dimensionally stable, and backed by a 50-year anti-rot warranty. Here's why Accoya is the only timber we use for flush and traditional window design across London.
No obligation · Accoya Approved Manufacturer
Accoya starts life as sustainably sourced, fast-growing softwood — but it doesn't behave like softwood once it's been through the acetylation process. This modification changes the wood at a cellular level, making it far less able to absorb moisture. Less moisture movement means less swelling, less shrinking, and dramatically less rot.
The result is a timber that outperforms most hardwoods on durability, while remaining light, stable and easy to machine into fine glazing bar profiles and mouldings. For window joinery — where the timber is exposed to the elements on one side and expected to hold a tight seal for decades — that combination is hard to beat.
We switched to Accoya as our default timber because we were tired of seeing beautifully made windows let down five or ten years later by rot at the sill or a swollen sash that wouldn't close properly. Accoya solves that problem at the material level, not just with better paint or better joinery.
As an Accoya Approved Manufacturer, we can offer a 50-year above-ground anti-rot warranty on qualifying Accoya installations — compared with the 10–15 years typically expected from standard softwood joinery, even when well maintained. For London homeowners investing in new windows, that's a meaningfully longer horizon before rot repair becomes a consideration again.
"Flush" refers to how the sash sits within the frame — flush with the outer face, rather than recessed behind it as with a traditional sash window. It's a look favoured on contemporary extensions, new builds, and renovations that want a clean, minimal sightline while still using real timber rather than aluminium or uPVC.
Flush design is unforgiving of timber movement. If the sash swells even slightly, it binds against the frame; if it shrinks, gaps open up and draughts follow. This is exactly where Accoya's dimensional stability matters most — because it barely moves with changes in humidity or temperature, a flush Accoya window keeps its tight, clean joint for decades rather than needing constant easing and adjustment.
We fit flush Accoya windows on rear extensions, loft conversions, new-build developments, and any project where the brief calls for a contemporary look without sacrificing the warmth and character of real timber.
Accoya isn't just for flush, contemporary designs — it's fully paintable and can be worked into any traditional sash or casement profile, glazing bar pattern, or moulding, making it equally suitable for period properties and Conservation Areas.
Accoya is produced from responsibly managed, fast-growing timber sources and is fully recyclable — an increasingly important consideration for homeowners weighing up materials for a long-term investment like new windows.
Whether you want a flush, contemporary design or a traditional sash profile for a period property, Accoya gives us a timber that will hold its shape and resist rot for decades. We're FENSA registered, Accoya Approved, and have been working across all London boroughs for over 15 years.
Get a Free Site SurveyWe have helped hundreds of London homeowners preserve the proportions and character of their period properties.
Finsbury Park
"Saved our original Victorian windows when others said replace. Beautiful workmanship — our sash windows look brand new."
Stoke Newington
"Draughts completely gone. Warm house for the first time in years. Fair price and they clearly know period properties inside out."
Central London
"They completely replaced two windows in our Edwardian home. Friendly, communicative and done quickly — in just 2 days."
North London
"The detailing is very well done and accentuates the property nicely. The whole front of the house looks much better as a result."
Accoya is sustainably sourced timber that's been modified through an acetylation process, making it dimensionally stable and highly resistant to rot, swelling and warping. We use it because it performs better than any other timber we've worked with — including many hardwoods — while remaining fully paintable and workable like traditional softwood.
Accoya windows come with a 50-year above-ground anti-rot warranty from the manufacturer — significantly longer than the 10-15 years typical of standard softwood joinery. As an Accoya Approved Manufacturer, we can offer this warranty on qualifying installations.
Flush design means the sash sits flush with the outer frame rather than recessed within it, giving a clean, contemporary sightline. Accoya's dimensional stability makes it especially well suited to flush designs, since it doesn't swell or shrink with moisture the way ordinary timber can, keeping the flush joint tight over time.
Yes — Accoya is fully paintable and can be worked into any traditional profile, glazing bar pattern or moulding, so it's suitable for both period sash windows in Conservation Areas and contemporary flush casement designs on new builds. See our listed building window guide for more.
Accoya typically costs more than standard softwood up front, but the extended lifespan, reduced maintenance and 50-year warranty make it excellent long-term value, particularly for exposed elevations or coastal properties where standard timber degrades faster.
Yes — flush Accoya windows are a popular choice for rear extensions, loft conversions and new-build developments across London, giving a clean contemporary look without sacrificing real timber. See our casement windows page for more on flush and contemporary profiles.
Whether you want a flush, contemporary design or a traditional sash profile, we offer a free, no-obligation survey and quote across London.
218 Hornsey Road, London, N7 7LL
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