Business Details
46 Years
experience
Your Trusted Partner for Timber Sash Windows in London
London Box Sash has been crafting high-quality timber sash windows in London since 1980. Founded by John Ellis, our family-run business combines traditional craftsmanship with modern engineering to deliver bespoke double-glazed sash windows that preserve architectural heritage while meeting contemporary energy efficiency standards. Our skilled artisans use sustainably sourced materials, including FSC-certified Accoya wood, to create durable, thermally efficient windows tailored to historic and modern properties. We maintain a strong commitment to local manufacturing, with 95% of installations within 10 miles of our London workshop, reducing environmental impact while supporting the local economy.Our team of experienced installers ensures precise fitting, complemented by a comprehensive service that includes restoration, repair, and consultation. Recognised with industry awards and FENSA registration, we prioritise customer satisfaction through transparent communication, meticulous attention to detail, and a dedication to continuous innovation in window design and sustainability.
Services
Sash Windows
Double-Glazed Sash Windows
Timber Windows
Window Installation
Bespoke Windows
Details
- Year established: 1980
Highlights and features
- Over 40 years of specialist experience in sash window craftsmanship
- Family-run business with generational expertise in traditional joinery
- FENSA-registered for building regulation compliance assurance
- Locally manufactured in London with 95% installations within 10 miles
- Carbon-neutral manufacturing mission by 2024
Associations and certifications
- FENSA
- Which? Trusted Traders
What people say
Excellent service
Highly skilled
Professional team
Superb quality
Perfect installation
Services
Sash Windows
Our handcrafted sash windows combine traditional joinery techniques with modern double-glazing technology. Made from sustainably sourced Accoya wood, these windows maintain historical authenticity while achieving A-rated thermal efficiency. Each window features precision-engineered components including high-performance pulley systems and security-enhanced hardware, ensuring smooth operation and long-term durability for London properties.
Double-Glazed Sash Windows
We transform traditional sash windows into energy-efficient solutions through advanced double-glazing technology. Our units incorporate thermally insulating Swisspacer bars and low-emissivity glass to reduce heat loss by up to 70%. The design maintains period-appropriate aesthetics while delivering modern performance benefits, including noise reduction and improved security for urban environments.
Window Installation
Our in-house installation team ensures perfect fitting of bespoke windows, with over 10 years' experience in London properties. The service includes protective sheeting, dust containment, and plaster repair as needed. Installers complete comprehensive clean-up and provide progress updates throughout the day, ensuring minimal disruption to homeowners while maintaining the highest standards of craftsmanship.
Bespoke Windows
We create made-to-measure windows tailored to individual property requirements. From Victorian bay sashes to contemporary flush casements, our design process considers architectural style, thermal performance, and security needs. Each bespoke window undergoes computer-aided design and laser-cut precision manufacturing to ensure perfect fit and finish for unique installations.
Window Restoration
Our restoration service preserves historic window features while upgrading functionality. We repair damaged timber components, replace failed double-glazing units, and reinstate traditional operating mechanisms. The process maintains original architectural details while incorporating modern improvements like draught-proofing and enhanced security features to extend window lifespan.
People
John Ellis
Founder
John Ellis established London Box Sash in 1980 after building his first woodworking machine from a skatepark project in 1978. With decades of experience in traditional joinery, he pioneered the company's commitment to combining heritage craftsmanship with modern window technology.
Patrick Ellis
Production Manager
Patrick joined the family business in 2002 after completing an apprenticeship and business degree. He now oversees production operations, bringing expertise in joinery and business management. Patrick conducts site surveys and ensures manufacturing maintains the company's high standards of quality and precision.
Jack Ellis
Business Director
Jack joined London Box Sash in 2010, taking daily operational responsibility alongside his brother Patrick. He has driven growth in supply and installation services, focusing on expanding the company's market reach while maintaining its commitment to traditional craftsmanship and customer service excellence.
Questions
What makes your sash windows energy efficient?
Our sash windows use A-rated double-glazing with thermally insulating spacers and sustainably sourced Accoya wood, reducing heat loss by up to 70% compared to single-glazed windows.
Are you FENSA registered?
Yes, we are FENSA registered, ensuring all window installations meet UK building regulations without requiring separate council approval.
How long does window installation take?
Most installations complete within 1-3 days depending on complexity, with our team providing progress updates and ensuring minimal disruption to your home.
Do you offer window restoration services?
Yes, we specialise in restoring historic sash windows, combining traditional repair techniques with modern upgrades like draught-proofing and security enhancements.
What areas do you cover?
We primarily serve London and surrounding areas including Surrey, Kent, and Essex, with 95% of installations within 10 miles of our Croydon workshop.
How are your windows manufactured?
Each window is made to order using computer-aided design and precision laser cutting, combining traditional joinery techniques with modern manufacturing technology for perfect fit and finish.
Reviews (3)
Kate Winter
Jan 22, 2018
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Excellent service from London Box Sash, right from my first contact with Jack and Patrick. They were not pushy at all, and were genuinely interested in helping me solve the condensation issues I was having with my old windows. My fitter did an excellent job and reassembled my room for me after he had replaced the windows. I am totally thrilled with them, and can't recommend London Box Sash more highly.
Lorna Buckle
Oct 11, 2017
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We recently had all the sash windows replaced at the front of our Victorian house. They are really beautiful, each one a work of art! :- We had amazing service from start to finish. Both Audi and Angelo worked efficiently, turned up when they said that they would turn up, finished the job when they said that they would and left the place spotless. The windows not only look impressive but we've already noticed the difference with sound and heat. We could not recommend Patrick and his company enough.
Sophie Kirk
Oct 06, 2017
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Really great service, workman arrived on time, he made sure the whole room and floors were covered with dust sheets and he did the job quickly. The work he did was great and the window looks incredible - could not recommend enough!
