London Box Sash Windows

Family run – manufacturing windows in London since 1981

With nearly 40 years of experienced craftsmanship, we create the finest range of sash windows, casement windows and doors – bespoke and tailored to suit your needs.

John Ellis started the business nearly 40 years, when he decided to take his passion for craftsmanship and joinery and create a window company based on offering the highest level of quality and service. With the help of his two sons, Patrick & Jack and backed up by a highly skilled team of craftsman London Box Sash has grown into London’s leading premium window and door manufacturer. As a family business, we have a deep understanding of manufacturing and installing professionally crafted windows, with a knowledge that is unmatched and truly valued, which helps us to create products that deliver on every level.

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Sash Windows

The ’50-Year Window’ is our premium option. With longevity and performance being the key factors, we combine traditional joinery methods with high performance double-glazing, draught sealing and the finest quality low maintenance micro-porous paint system, ensuring optimum durability.

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Casement Windows

Years of customer collaboration and advances in technology have helped us develop our bespoke 50-Year casement window into one of the highest performing on the market. While we wanted to make our windows thermally efficient, we also wanted to stay true to the heritage of the casement window.

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French Doors

Our French doors have been designed to exceed industry standards in performance, insulation, security and finish whilst maintaining their original features. The range is fully bespoke and can be customised to suit your requirements, with the option of different moulding and glazing bar configuration.

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The ’50-Year Sash Window’ is our premium option. With over 30 years of research and development we have designed our sash window range to incorporate everything our customers had been asking for and more. With longevity and performance being the key factors, we combine traditional joinery methods with high performance double-glazing, draught sealing and the finest quality low maintenance micro-porous paint system, ensuring optimum durability.

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  EXTRA DURABLE – Timber guaranteed against rot for 50 years
• EXTREME STABILITY – 75% reduction in shrinkage and swelling
• LOW MAINTENANCE – 3-4 times longer lasting paint finish
• ROBUST CONSTRUCTION – Traditional mortice and tenon joints
• SYMPATHETIC – Traditional features replicated like for like
• HIGH PERFORMANCE – A rated double-glazed units
• NATURALLY INSULATING – Improved thermal insulation

Because our customers want their windows to last we have always used the highest quality wood available. Now 95% of all our sash windows are made from the best wood available on the market – Accoya® wood. Accoya® wood is the result of more than 80 years of research and development that brought together a long established and extensively proven wood modification technique – acetylation – and leading-edge proprietary technology to create a high performance wood.

Accoya® wood is the leading high-technology wood. Created from sustainably sourced wood, Accoya® matches or exceeds the properties of the very best tropical hardwoods. See above for some of its performance benefits.

Here at London Box Sash Windows we feel the glass that’s used in our sash windows has one of the most important roles of all, as most of our customers want to improve their quality of life and reduce energy costs by improving thermal performance. That’s why we glaze our premium sash windows to ‘A’ rated specifications, exceeding the latest building regulation requirements.

The windows are glazed with 24mm double-glazed units, comprising of low ‘E’ glass, argon filled ‘Swisspacer’ bar and Pilkington Optiwhite extra clear, low iron glass, which provides an indicative centre pane U-Value of 1.2 W/m2K.

To protect and prolong the life of our double-glazed units we have designed a unique drained and vented rebate glazing system to prevent premature failure of glazing unit seals by allowing any trapped moisture to drain through small, concealed drainage holes. This has allowed us to double our guarantee against premature failure.

Our sash window range can also incorporate a variety of other glass options to suit specific requirements:

• Toughened glass or laminated glass.
• Acoustic glass – Double-glazed units can incorporate acoustic insulating 6.8mm laminated glass (35db Rw). This product combines two sheets of clear glass bonded together with a totally transparent interlayer. The interlayer absorbs sound and reduces the level transmitted through the glass, helping to keep noise in or out.
• Obscured or textured glass.
• Stained glass

One of our customers’ biggest concerns is having to paint their windows every couple of years. To minimise this requirement we spray finish all our Accoya® sash windows with the finest Teknos low-maintenance microporous paint systems, coupled with end grain sealing and highly-skilled spray application, giving us an unrivalled, long-lasting paint finish. Because our premium sash window range is made using Accoya® exclusively, maintenance cycles are greatly extended and on redecoration only require one topcoat.

We can also colour match to Dulux, Farrow & Ball, Crown or RAL.

Our premium sash window range comes fully draught sealed. They have a perimeter brush pile polypropylene stripping, discreetly contained within concealed carriers installed to all staff and parting bead, maximising thermal and sound efficiency.