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Sash Windows – Hand Crafted in London

London Box Sash is London’s leading premium manufacturer and installer of traditional timber sash windows and doors. Operating out of our factory in southwest London, our product range includes sash windows, casement windows, doors and a varied amount of bespoke commissions. With more than 30 years as a family owned and run company, we understand our customers’ needs.

That’s why we produce a quality product with a high level of customer service every time. Our goal at London Box Sash Windows is to meet targets on price, quality and service. Together with our dedicated team, we are committed to continuously improving and innovating our product, so our customers always get the best possible experience.


To get an instant estimate of the cost of the work you need done, click here and let us know a bit about what you need. We’ll get back to you to discuss your project in more detail!

Alternatively, fill in the quick form below and we’ll get back in touch to give you an accurate quote.

Quick Enquiry

We’d love to hear from you. Contact us today with your window or door enquiry.

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About Us

We’ve been operating a family run business, making windows for satisfied customers, for more than 30 years now. A lot has changed since then, but our mission hasn’t. We believe that good work speaks for itself. That’s why we always aim for the highest quality in our products and in our level of dedicated service. That’s why more than 85% of our business comes from repeat customers or word of mouth. And that’s just how we like it.

Read what some of our happy customers have to say about us here

Sash Windows and Beyond

It’s in our name, it’s our flagship product and it’s what we’re known for. But it’s not all we do. Have a look at our main products listed below, or get in touch to discuss any project you’ve got planned.

Sash Windows

The ’50-Year Sash 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.

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.

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.

Strength, Durability & Quality

We set out to produce quality windows look good, feel good and last. And after years of development and research, we’ve got the perfect formula and we’re happy to present to you the result of our work – the premium 50-year window.


We make 99% of our casement and sash windows are made using premium Accoya wood. Accoya is an advanced form of timber, modified through a process called acetylation that massively increases its overall strength and durability, matching and even exceeding top-end tropical hard woods. Accoya is created from high quality, sustainably sourced wood.

Design & Finish

Materials are hugely important, but they’re nothing if you don’t use them properly. We’ve been honing our craft ever since we started all those years ago, and our dedication and attention to detail shows in our products. Whether it’s the traditional joints and details or the premium latches and locks, every bit of every one of our windows is carefully considered and adds to their aesthetic and functional quality. We finish our windows using Teknos microporous paint systems; this means long lasting low-maintenance coats.