London Box Sash Windows

What London Box Sash Windows does

London Box Sash Windows Ltd is a family-owned UK private limited company that designs, manufactures, and installs bespoke timber sash windows for residential customers. Founded in 1980 by engineer John Ellis and now run day-to-day by his sons Jack and Patrick Ellis, the company operates from a single factory at 9 Tramsheds, Coomber Way, Croydon, with a by-appointment showroom at 341 Norwood Road, Herne Hill. It serves homeowners of Victorian, Georgian, and Edwardian period properties across South London, broader London, and Surrey, with the business stating that 95% of installations occur within 10 miles of the workshop.

The company's core product is handcrafted box sash windows made primarily from Accoya acetylated timber, combined with A-rated double-glazed units and a drained and vented counterweight system backed by a 10-year guarantee. Secondary offerings include timber casement windows and bespoke timber doors (including balcony doors), finished using Teknos spray coatings. Manufacturing and installation are performed entirely in-house, with no channel partners or third-party installers, supported by over £4 million of cumulative investment in plant and machinery and FENSA self-certification for building regulation compliance. Material inputs (Accoya, Teknos) are sourced through established supply partnerships.

The revenue model is project-based and one-off: each window is custom-manufactured and installed at an average fully fitted price of £2,000-£4,000 per unit, with revenue streams spanning new sash window supply-and-fit, casement windows and doors, and repair/aftercare services. Go-to-market is direct-to-consumer and sales-led, combining an SEO-driven website with an online Instant Estimate tool, phone enquiries, a physical showroom, and a field sales/survey team conducting home visits for quotes. Distribution is exclusively direct, and the company relies heavily on word-of-mouth referrals, Google reviews (4.9 rating across 189+ reviews), Which? Trusted Trader accreditation, and location-targeted content marketing to generate leads.

Name

London Box Sash Windows

Legal name

London Box Sash Windows Ltd

Website

https://londonboxsash.com

Company type

Private

Founded year

1980

Operating status

Operating

Headcount range

11–50 employees

Ownership category

akta.pro rank

Product category

Timber Sash Window Manufacturing and Installation

NAICS

Wood Window and Door Manufacturing (321911), Custom Architectural Woodwork and Millwork Manufacturing (337212)

akta.pro primary industry

Windows (IMADAIAC)

akta.pro secondary industry

Frames, Sashes, Mullions & Subframes (IMADAIAH)

Keywords

• Timber sash windows
• Box sash windows
• Double glazing installation
• Period property windows
• Timber door manufacturing

Headquarters

HQ city

Croydon

HQ country

United Kingdom

HQ region

Europe

Offices2 records

Markets served

GTM type

B2C

Offering type

Hardware or Manufacturing

Cost components

Personnel, Supply Chain, Operations, Marketing or Sales, Infrastructure, Technology or R&D

Revenue model

1. Timber Sash Window Sales & Installation: One-time purchase model for bespoke timber sash windows. Windows are custom-manufactured and installed by company's in-house installation team. Price includes manufacturing, supply, and professional installation. Additional services include repair work and replacement projects.
2. Casement Window Sales & Installation: Sale and installation of timber casement windows as secondary product line. Also offers timber doors including balcony doors, matching the company's heritage aesthetic approach.
3. Window Repair Services: Repair services for existing sash windows. Company has repaired windows for customers years after initial installation. Aftercare and snagging support included with installations.

Pricing tiers

Go-to-market motion3 records

Distribution channels4 records

Marketing channels7 records

Core offering

London Box Sash Windows designs, handcrafts, and installs bespoke timber box sash windows for period properties in London. Using traditional joinery combined with modern A-rated double glazing and Accoya acetylated timber, the company manufactures every window to order in its own South London (Croydon) factory and fits them with an in-house installation team. It also supplies casement windows, timber doors (including balcony doors), and provides repair and aftercare services for existing sash windows.

Product overview

London Box Sash Windows is a family-run London workshop specialising in high-quality timber sash windows for period homes. The company operates a single-site manufacturing model, designing, crafting, and installing bespoke wooden sash windows from their own workshop. Their core product line centres on traditional box sash windows and sliding sash windows, available in timber and Accoya wood variants, all featuring double-glazing and A-rated energy efficiency. The product portfolio is unified around sash window craftsmanship, supplemented by casement windows and timber doors as secondary offerings. All products are manufactured in-house in their South London factory and installed by their own screened installation teams.

Differentiator

Problem solved

Functional benefit

Products and services

• Timber Box Sash Windows
• Timber Casement Windows
• Bespoke Timber Doors
• Sash Window Repair and Aftercare Services

Quantifiable outcome

• Potential energy savings of approximately £195 per year for a standard semi-detached home upgrading from single-glazed to A-rated double-glazed windows (Energy Saving Trust)
• +3 more outcomes

Named customers5 records

Segments3 records

Ideal customer profiles2 records

Technology focussed No

API detail

Has API

No

API docs

API detail

Core technology

AI maturity

App detail

Feature4 records

Partnerships

Four partnerships are on record, tiered minor and core.

• GGFi (Installsure)minorOthersGGFi (through InstallSure) provides window guarantee protection for London Box Sash Windows installations. Offers consumer protection and guarantee backing for installed products, enhancing customer confidence in the company's offerings.
• AccoyacoreTechnology or IntegrationAccoya is the official joinery manufacturer partner for London Box Sash Windows. The company uses Accoya wood as their primary material for sash windows. Accoya wood undergoes advanced acetylation process for exceptional durability and sustainability. London Box Sash Windows is listed on Accoya's official website as a factory location partner.
• FENSA (Fenestration Self-Assessment Scheme)coreOthersFENSA is a government-approved scheme that monitors building regulation compliance for replacement windows and doors in England and Wales. London Box Sash Windows is FENSA registered, meaning they can self-certify their installations meet building regulations without requiring individual building control approval from local authorities.
• Dispute Resolution Ombudsman (via Which? Trusted Trader)minorOthersWhen complaints cannot be resolved through the company's internal complaints procedure, customers can refer disputes to Dispute Resolution Ombudsman through Which? Trusted Trader process. Provides independent dispute resolution for consumer protection.

Scale indicators6 records

Recent moves6 records

Expansion highlights5 records

Broad incumbents

• Anglian Home Improvements: One of the UK's largest home improvement companies offering windows, doors, and conservatories nationwide. Competes on homeowner window replacement spend at scale, but serves a mass-market uPVC-led customer rather than bespoke heritage timber sash.
• Crittall Windows: Heritage British steel window brand with broader fenestration portfolio serving residential, commercial, and conservation markets. Adjacent in the period-property fenestration category but specializes in steel rather than timber sash.
• Everest: Large UK national installer of uPVC, timber, and aluminium windows and doors. Competes for the same homeowner replacement demand at scale, but with mass-market positioning and primarily uPVC product (vs. London Box Sash's premium timber sash focus).

Direct peers

• Ventrolla: Specialist UK sash window renovation, repair, and replacement company focused on period properties. Highly comparable in heritage customer base, vertical integration (manufacture and install), and product positioning against uPVC alternatives.
• The Sash Window Workshop: UK specialist manufacturer and installer of bespoke timber sash windows for period properties. Closest direct competitor in product, customer segment (heritage homeowners), and service model (made-to-measure, in-house manufacturing and installation).
• Dale Joinery: UK timber window and door manufacturer serving period and listed properties with engineered timber and Accoya products. Comparable in premium positioning, sustainability credentials, and bespoke heritage customer segment.
• Timber Windows London: London-based bespoke timber window and door manufacturer targeting period properties. Competes on the same South London geography with comparable Accoya/engineered-timber product range and direct-to-consumer sales model.
• Evolution Windows: Manufacturer of timber-look uPVC and composite windows marketed at period-style replacement. Competes for the same London period-property buyer seeking aesthetic + double-glazing performance, but at lower price points than London Box Sash.
• Mumford & Wood: Essex-based manufacturer of high-end timber windows and doors for heritage and conservation projects. Comparable in bespoke manufacturing, premium Accoya/timber product range, and listed-building/period-property customer focus.

Others

• Accoya (Accsys Technologies): Manufacturer of Accoya acetylated timber and upstream partner to London Box Sash Windows. Not a competitor but a key enabling supplier whose product roadmap, pricing, and certification directly shape the company's value proposition.

Market position

Weaknesses4 records

Competitive moat4 records

Key risks6 records

Key highlights6 records

Customer concentration

• Xx.com/londonboxsash
• YouTubeyoutube.com/@londonboxsashwindows9817
• Facebookfacebook.com/londonboxsashwindows
• Instagraminstagram.com/london_box_sash_windows
• LinkedInlinkedin.com/company/london-box-sash-windows-ltd

Revenue estimate

Valuation estimate

Number of profiles

Profiles4 records

Funding overview

Funding rounds

Investors

Funding detail is available on the Subscription and Enterprise plan.Contact sales →

M&A

Investments

M&A and investment is available on the Subscription and Enterprise plan.Contact sales →

Frequently asked questions about London Box Sash Windows