Trade Supply
Landmark Windows Co Ltd has over 40 years experience supplying high-quality timber sash windows, casement windows, and doors directly to the trade.
From our London workshop, we work with specialist sash window companies, builders, and architects across London and the South East. Manufacturing joinery that meets the demands of listed buildings, conservation areas, and traditional properties.
Who We Work With
Installers
Your reputation matters - and we treat it with the same care as our own.
That's why we offer flexible supply options, from fully finished and glazed sash windows ready for installation, to part-finished products you can complete in your own workshop to suit your workflow and preferences.
Builders
Wheter you're working on a single home or a larger residential shceme, our hardwood sash windows bring lasting value and character to your clients' properties.
With the capacity to design and manufacture to your specifications - on time and within budget - we're a reliable partner to heritage-sensitive builds and refurbishments.
Architects
We work closely with architects to design bespoke timber windows and doors that complement the overall vision of a project - ensuring historical accuracy, material quality, and long-term performance. If you're specifying high-quality hardwood sash windows and doors, we're here to provide expert guidance on detailing, glazing options, and compliance with conservation requirements.
Supplying the Trade
We offer flexible supply options to suit your workflow, including part-finished, unglazed, or fully finished products.
Whether you need sliding sashes for retrofitting or complete box sash windows and bespoke doors for full replacements, Landmark delivers reliable, consistent joinery. Built to heritage standards and trusted by professionals.
As a dedicated manufacturing workshop, we work exclusively with timber and support businesses across the trade who specialise in servicing, maintaining, and upgrading period and listed properties.
Our London Workshop
Trusted by homeowners to protect, restore, and improve some of Britain’s most treasured buildings. We support our trade clients with joinery that not only meets the technical and aesthetic demands of heritage work but also reinforces their reputation for quality, reliability, and expert care.
From bespoke solutions to repeatable project specific windows, we help you deliver lasting results for your clients.
We value long-term relationships, not just transactions. Our team is committed to clear communication, dependable lead times, and consistent product excellence.
So you can quote with confidence, install without worry, and grow your business with a supplier who understands what’s at stake.
We work with a trusted network of trade professionals who share our standards in quality, reliability, and heritage joinery. Whether you’re a sash window company, builder, or conservation-led architect, becoming a Landmark trade client gives you access to dependable manufacturing, tailored support, and practical tools to grow your business.
Initial Consultation
We’ll discuss your business model, supply preferences, and the types of projects you typically take on — from retrofit sash replacements to full box frame installations and bespoke doors.
Quotations & Ordering
Receive clear, itemised quotes tailored to each job. Once approved, your order enters our workshop schedule, with all joinery made in-house using traditional techniques and selected hardwoods or Accoya.
Finishing Options
Choose what suits your operation: fully finished and glazed, or part-finished and unglazed for completion in your own workshop.
Collection or Delivery
We offer flexible collection from our Hertfordshire workshop or arranged delivery depending on location and order volume.
Trade Client Beneifts
As a Landmark trade client, you gain direct access to our London workshop , conveniently located for London and the South East.
Trade partners are welcome to visit and tour the facility, view samples, and choose from over 50 traditional moulding profiles.
Preferential Pricing & Lead Times
Competitive trade rates on all joinery, with lead time priority built into our production schedule.
Filtered Job Opportunities
We refer warm leads based on your service area and availability — offering additional work where suitable.
Marketing Support
Access to branded materials, product imagery, and text support to help you promote Landmark-quality products under your own name.
Lead Tracking Tools
Optional use of our tracking system to help you manage project enquiries, streamline admin, and stay organised.
Dedicated Account Manager
One point of contact for pricing, updates, and ongoing support — making communication straightforward and efficient.