For Over 20 Years We Have Been Replacing Sash Windows, Casement Windows and Period Doors.
Our window repair service can restore most traditional sash windows, casement windows and doors but occasionally some frames do need replacing. By paying close attention to copying the fine detail such as sash horn shapes and moulding profiles we create authentic replicas of your current window frames.
The new glass will let more light into your room, whilst the Low-E coating reflects heat to keep your home warmer in winter and cooler in summer.
The discreetly hidden draught seals are low friction to improve sliding functionality, but tight enough to stop rattles, ensuring a cosy and energy-efficient period home.
Replacement sash windows are individually made to measure.
We can replicate any heritage glazing pattern or intricate window shape, to ensure the original charm of your heritage home remains unaltered.
Time-proven traditional construction, combined with a 50-year guarantee from Accoya wood, ensures that our double glazed sash windows will last a lifetime.
Save on fuel bills and lower your carbon footprint with Low-E glazing and draught seals.
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Our sash window workshops manufacture bespoke timber windows & doors in any style, constructed using traditional mortise & tenon joints. Suitable for conservation areas and listed buildings.
We carefully reproduce a copy of your original windows, paying close attention to the original horn shape, timber mouldings & sectional details. Preserving these fine details, that vary by region and era, is important to maintain the architectural significance of your heritage property.
If the original window frames are missing or replicas are required for building alterations then we can work from old photos or copy the architectural details from a neighbouring property.
The Edwardian’s and Victorians perfected the construction of wooden windows, structurally we build them just as they did. Our modern sash windows only differ from the originals by using modern glues, built-in weather seals and improved glass technology.
Glued and wedged mortise & tenon joints, bonded with modern glues, ensures that our joinery is of the highest quality possible and built to last. Some other companies do offer cheaper timber windows constructed using cost cutting methods and cheaper grades of wood. Typically these cheap sash windows only last 15 – 20 years and do not represent good value. At Sash Window Specialist we only supply traditional period windows that are built to last.
Draught seals are machined into the timber components to become an integral, practically invisible part of the windows or door. Brush draught seals are the best option for a sliding sash window but compression weather seals are better suited to doors.
Accoya® wood is the perfect material for most timber window frames and external wooden doors. 50 year anti-rot guarantee
Dimensionally stable
Accoya® wood represents a major development in wood technology. It enables the consistent supply of durable, non-toxic, dimensionally stable wood. This makes it an ideal material for manufacturing high performance, exterior timber products. Accoya is manufactured through the acetylation of plantation grown softwood. For over 80 years this has been the gold standard in the academic field of wood science. A breakthrough in closed-loop engineering, culminating in 2007, led to the first commercial scale production of the product in the world.
Period windows and doors made with Accoya have a 50 year guarantee, giving complete confidence that Accoya® windows and doors will stand the test of time. An Accoya® wooden window or door is developed to excel in external applications, even in challenging conditions.
Bespoke joinery is also available from a range of other premium timbers.
Read more : Guide to sash window timber
Replacement windows and doors must comply with local building regulations, unless a legal exemption is in place for heritage conservation. New windows will require Low-E laminate glass or double glazing to achieve energy efficiency compliance.
If your property has intact hand made glass or lead-light then some consideration should be given to reusing the existing heritage glass. We can not guarantee every single pane intact but it is usually possible to transfer heritage glass. Transferring glass in this way may necessitate boarding up your existing windows whilst the new windows are in production. Ideal for conservation areas and listed buildings.
The thickness of your existing sash window frames dictates the room we have to work with in order to include the best energy-efficient double glazing.
The spacer bar inside the glass unit governs the cavity between the two panes. The wider the cavity the better the energy efficiency will be, but there is a law of diminishing returns. The first 5mm of the cavity is responsible for the most significant insulation improvement but a 10mm void is not twice as good as 5mm.
12mm is the average thickness of the spacer bar that we use in new sashes, but with thin sashes or if you choose to incorporate a thick laminate or acoustic glass then we may use a thinner spacer bar. A 16mm spacer bar is reserved for much thicker sashes, typically found in heritage public buildings.
Spacer bars can be either rigid aluminium duplex bars or ‘warm edge’ flexible foam spacer tape. A warm-edge spacer bar performs slightly better at reducing heat conduction around the unit perimeter.
Not all double glazing is created equal. When double glazed units (dgu) first came to the market they simply comprised 2 panes of glass separated by an air space. Whilst we can still supply these budget d.g.u. the saving over low-e units is not a sensible cost cutting measure.
Low-e double glazing outperforms those early double glazed units by a large margin. Firstly the air space is now filled with an inert gas that conducts heat less readily. Secondly, Low-E coatings baked into the glass surface reflect any heat energy back to its source, resulting in significant improvements to the insulating properties.
Pilkington K glass is the best-known energy efficient, low-e glazing, but all glass manufacturers offer comparable products.
Low-e glass has a special coating that reflects heat back into the room. In winter heat is reflected back indoors, in the summer heat from the
sun is reflected away keeping the room cooler.
Because a Low-E coating reflects some wavelengths of the light spectrum it will slightly alter the colour tone of the light passing through the glass. There are various Low-E coatings offered by different glass manufacturers that each have their own colour signature and performance characteristics. Ask your local branch representative about the options on offer in your area.
A gas-filled unit features an inert gas in the cavity between the glass panes. Using an inert gas that is denser than air stops circulation within the unit, which may lower overall efficiency. Argon is the most commonly selected gas as it provides the best value.
Single Unit
Using one glazed unit per sash is the best value.
Timber beads are bonded to the exterior pane of glass mimicking the interior glazing bars that are mortice and tenon jointed to the outer sash frame. Sealed inside the glass unit are matching spacer bars to fill the void, creating a solid glazing bar effect. Internal spacers also brace the panes and reduce any flexing of the glass.
Our bonded beads are custom made to the same thickness as your original sashes, ensuring the overall charm of the period property is preserved.
We have been offering this system for over 20 years, it is a very durable solution.
Glazing this way allows us to recreate more intricate glazing patterns that are prohibitively expensive when using many separate, shaped glazing units.
Slimlite/Slimline Glazed units & Pilkington Spacia Units
Fitting many individual glazed units is more expensive, but can add a little more character to the glazing of multi-paned sashes. As each unit will sit slightly out of level with its neighbour some of the ‘flatness’ that a single unit creates is reduced.
Energy efficiency is slightly reduced by selecting the slimlite 5mm spacer bar option, but some people prefer the look of a thinner unit with slightly more ‘meat’ left in the timber sash.
The weak spot of all double glazed units is the edge. If the seal around a glazed unit fails then the inside of the glazed unit can mist up. The simple fact that this option increases the number of glass edges also increases the potential weak spots.
Slim units can be beneficial for double glazing existing sash frames.
For sashes with no glazing bars, a single unit is used anyway.
Our Double Glazing Options Include
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We offer a wide range of hardware options, available in a variety of finishes.
Bespoke period sash windows can reduce the draughts by almost 90%, therefore significantly reducing the air cooling or heating requirement needed for the room. Warm or cold draughts make air cooling and heating systems work harder and make occupants feel uncomfortable, often adjusting room thermostats to compensate.
The natural insulating properties of timber make this an extremely energy efficient building material. Timber window frames are highly energy efficient as they do not conduct heat.
Wood is a sustainable building material, derived from a renewable source. Any home owner choosing green living should consider preserving or reinstating timber windows.
Reading Sash Windows upgraded with Low-E Double Glazing. These Victorian sash windows in Reading, Berkshire were upgraded with bespoke timber sashes, fitted into the existing
Bespoke Period Doors with double glazing. Muswell Hill, London. This bespoke door frame set is installed in Muswell Hill, North London. Made and fitted by
Bespoke Period windows with double glazed sashes. Westminster, London. This inward opening casement window in Regents Park, Westminster was beyond economic repair. A replacement
Specialist Window Contractor | Parliament House, Western Australia. As a specialist window contractor we were awarded Phase 1 of the renovation work at parliament house
