Timber Casement Windows London
Master Crafted · FENSA Registered · 50-Year Timber Warranty
London's premier specialists in bespoke timber casement windows. We design, manufacture, and install made-to-measure casement windows for period and contemporary properties across the capital — combining traditional joinery methods with Accoya® high-performance timber. Heritage styles our speciality.
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Casement Windows London: Premier Timber Specialists
At Golden Ratio Sash Windows & Doors, we design, manufacture, and install bespoke timber casement windows London-wide. Our master craftsmen combine traditional joinery methods with modern technology to deliver windows that are beautiful, thermally efficient, and built to outlast the property they're fitted in.
Whether you're upgrading a period Victorian terrace, restoring a Georgian townhouse, or fitting contemporary casements in a new build — every window is made to measure, finished to your specification, and installed by our own team.
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What Is a Casement Window?
A casement window is a window whose opening part — the casement — is hinged to its frame and swings open like a door, rather than sliding. Most are hinged at the side and open outwards (side-hung). Others are hinged at the top and push out from the bottom (top-hung), which lets them sit open for ventilation in light rain.
That is the key difference from a sash window. A sash slides vertically in its box frame on cords and weights; a casement pivots on hinges. Plenty of London period homes have both — sliding sashes on the front elevation, and casements to the rear, in dormers or on later extensions.
The parts are simple: an outer frame fixed into the masonry, one or more opening casements, fixed lights that do not open, and the mullions (vertical) and transoms (horizontal) that divide them. How a casement holds itself open, and whether you can clean the outside of the glass from indoors, comes down to its hinges — see our guide to window hinge types.
The Benefits of Our Timber Casement Windows
Every casement window we produce is built to a single standard — the highest. Here's what you get as standard:
- Superior Energy Efficiency — double-glazed units eliminate draughts and significantly reduce heat loss, cutting energy bills year-round.
- Fully Draught Proofed — high-quality compression seals prevent rattles and cold draughts from day one.
- Noise Reduction — premium glazing options significantly reduce London street noise.
- Uncompromising Security — all windows feature insurance-approved multi-point locking systems.
- Exceptional Ventilation — hinged casements open fully for excellent airflow and maximum natural light.
- Low Maintenance — Accoya® timber requires repainting only every 10–12 years, not every 3–5 like softwood.
Types of Timber Casement Window
Every property is different, so every window is made to measure. We make five types, all fully customisable:
- Flush Casement Windows — the traditional choice, where the sash sits flush within the outer frame. Clean lines, ideal for period and contemporary properties alike.
- Storm-Proof Casement Windows — the opening sash overlaps the outer frame on the outside, giving a stepped profile and a double weather seal. The more common modern style, well suited to exposed elevations and rear extensions.
- Period Casements (Georgian, Victorian & Edwardian) — authentic glazing bar patterns, period proportions, and traditional ironmongery, including period-correct butt hinges (see our guide to window hinge types). Indistinguishable from the originals.
- Double / French Casements — two sashes opening from the centre for unobstructed views and maximum ventilation. Ideal for garden-facing rooms.
- Casement Bay Windows — angled or square bay configurations to maximise interior light and space.
All styles available in Accoya®, softwood, hardwood, or oak. Finished in your choice of colour or natural timber.
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Why We Use Accoya® Timber
Accoya® is an ultra-high performance wood made from sustainably sourced timber, modified through a patented acetylation process. The result is timber that is dimensionally stable in all weather conditions — meaning your casement windows will never stick, warp, or swell with the seasons.
Golden Ratio Sash Windows & Doors is an approved Accoya® manufacturer — one of a select group of London joiners certified to work with this material. It carries a 50-year above-ground warranty and requires repainting only every 10–12 years.
Accoya® is Cradle-to-Cradle Gold certified for sustainability — the right choice for your home and the planet.
Timber Comparison: Accoya® vs Hardwood vs Softwood
The upfront cost of Accoya® is higher — but over the life of your windows, it's significantly cheaper to own.
| Factor | Accoya® Timber | Hardwood (Oak / Sapele) | Softwood (Pine) |
|---|---|---|---|
| Expected Lifespan | 50+ Years (above ground) | 30–40 Years | 10–15 Years |
| Swelling & Shrinkage | Minimal — 75% less than other timbers | Moderate — can stick in winter | High — prone to warping |
| Maintenance Cycle | Every 10–12 years | Every 5–7 years | Every 3–5 years |
| Warranty | 50 Years (above ground) | Manufacturer dependent | Limited |
| Sustainability | Cradle-to-Cradle Gold Certified | Variable (slow growth species) | Standard FSC |
Manufactured to the Highest Specification
Every casement window we produce is built in our own workshop to exacting standards. We work closely with each client through the design and planning process to ensure accurate measurements and a style perfectly suited to their property.
- Fully draught proofed with compression seals
- Inner mouldings scribed and machined to specification
- Timber pressure-treated against wet rot, dry rot, and wood preservative
- Available in softwood, hardwood, oak, and Accoya® specialist timber
- Primed with microporous paint (unless otherwise requested)
- Supply only, supply & measure, or full supply and fit service available
Conservation Areas & Listed Buildings
Timber casement windows are the preferred choice of planning authorities in London's conservation areas. We have extensive experience producing period-accurate casements that meet heritage requirements for Georgian, Victorian, and Edwardian properties.
For listed buildings, we can produce windows that are like-for-like replacements in every detail — matching original glazing bar profiles, glass types, and ironmongery. We can advise on planning requirements during your free site survey.
How to Get Your Casement Windows
- Get in Touch — fill out the form on this page or call us on 020 3488 1695. We'll respond within hours.
- Free Site Survey — one of our London specialists visits your property, takes accurate measurements, and discusses your style options.
- Fixed Written Quote — a detailed, no-obligation quote with full specification. No surprises on the day.
- Manufacture & Install — your windows are built in our workshop (typically 6–8 weeks lead time) then installed by our own team.
Real Reviews from London Homeowners
Don't take our word for it — here's what our customers say about our casement windows London service.
London's Go-To Experts for
Timber Casement Windows
We combine the craftsmanship of traditional joinery with the performance of modern materials. Every window is made to last a lifetime.
Accoya® Approved Manufacturer
One of a select group of London joiners approved to manufacture with Accoya® — the world's leading high-performance modified timber. 50-year warranty. No swelling. No sticking.
Period Property Specialists
Georgian, Victorian, and Edwardian casement windows reproduced to authentic period specifications. Glazing bars, ironmongery, proportions — all matched to your property.
Insurance-Approved Security
All casement windows fitted with multi-point locking systems that meet insurance requirements. Secure, tested, and compliant with current building regulations.
4.9★ — 150+ Reviews
Over 150 five-star Google reviews from London homeowners. Our reputation for precision craftsmanship, honest advice, and clean installation speaks for itself.
Our Own Workshop & Team
Every window is manufactured in our own London workshop and installed by our own team — no subcontracting. One team, one standard, full accountability.
All London Boroughs
Based in North London (N7), we cover all of Greater London — Islington, Hackney, Camden, Haringey, Kensington, Chelsea, and every borough in between.
Recent Casement Window Projects Across London
A selection of our recent bespoke timber casement windows London projects.
Casement Windows London — FAQs
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What is a casement window?
A casement window is a window whose opening part is hinged to its frame and swings open like a door, rather than sliding. Most are side-hung and open outwards; top-hung casements push out from the bottom. They are fixed into an outer frame alongside any fixed lights, divided by mullions and transoms.
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What is the difference between a casement and a sash window?
A casement window opens on hinges, swinging outwards like a door. A sash window slides vertically within a box frame, balanced by hidden cords and weights. Casements give a full, unobstructed opening for ventilation; sashes are the classic choice for Georgian and Victorian front elevations. Many London period homes have both.
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Can you replace uPVC casement windows with timber?
Yes — uPVC-to-timber casement window replacement is work we do regularly. We remove the existing uPVC windows and replace them with timber casements made to the property’s original design, matching the proportions, glazing bars and sightlines. It is often the first step in restoring a period elevation, and in many conservation areas timber is what the council expects — see our conservation area window rules guide. Our front elevation case study shows a full PVC-to-Accoya replacement.
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How much do timber casement windows cost in London?
Timber casement windows in London start from £2,150 per window for a double-glazed unit, depending on size and timber specification. Accoya® timber costs more upfront but carries a 50-year warranty and requires far less maintenance than softwood — making it significantly cheaper over the lifetime of the window. We provide a free site survey and fixed written quote before any work begins.
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What is the best timber for casement windows in London?
Accoya® is widely considered the superior choice. Unlike traditional softwood or hardwood, Accoya does not swell or shrink with seasonal changes — so windows open and close smoothly year-round. It carries a 50-year above-ground warranty, needs repainting only every 10–12 years, and is Cradle-to-Cradle Gold certified. Golden Ratio Sash Windows & Doors is an approved Accoya® manufacturer.
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Can you match casement windows to a period property?
Yes — we specialise in period casement windows for Georgian, Victorian, and Edwardian properties. We replicate authentic glazing bar patterns, traditional ironmongery, and period proportions exactly. Every window is made to measure from your property's specific dimensions. The finished result is indistinguishable from original period joinery.
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Are timber casement windows suitable for conservation areas?
Yes — timber casement windows are the preferred choice of planning authorities in London's conservation areas and for listed buildings. We are highly experienced in producing windows that meet heritage specifications. We can advise on any planning requirements during your free site survey.
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Do your casement windows come with double glazing?
Yes — all our casement windows are double glazed as standard. We use slimline units where heritage appearance is required, which are accepted by most conservation authorities. All glazing meets current building regulations and significantly improves both thermal and acoustic performance.
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How long does casement window installation take?
A single casement window installation typically takes half a day to one full day. A full house of 6–8 windows is usually completed in 2–3 days. Bespoke manufacture lead times are typically 6–8 weeks from order confirmation — we'll confirm your specific lead time during the quotation process.
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Do you offer a supply-only service?
Yes — we can supply casement windows only, supply with a measure-up service, or supply and fit with full installation. We work closely with builders, architects, and directly with homeowners. Contact us to discuss which service best suits your project.
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What areas of London do you cover?
We cover all of Greater London. Based in North London (N7), we serve Islington, Hackney, Camden, Haringey, Kensington, Chelsea, and all London boroughs. Contact us to confirm coverage for your specific postcode.
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