SECURITY SASH WINDOWS
We design and build the UK’s most secure sash windows
At Sash Vault, we create a new standard for timber security sash windows. We are the only manufacturer in the UK with a secure sash window approved for use in Grade 2 listed buildings – a distinction that speaks to both authenticity and advanced engineering.
Our patented construction is completely unique: a stainless steel inner structure concealed within a timber frame. On the outside, it appears traditional. On the inside, it resists crowbar attacks and even bullets.
Each window is made in-house, tailored to your property in shape, proportion, curvature, style and glazing. Every detail is intentional – from the durable Accoya and Medite Tricoya engineered wood, to the secure ventilation lock and vault-grade locking system. Whether single or double glazed, our glazing options offer high UV performance, reflection control and optional bulletproof protection.
We are a family-run British company driven by design, innovation and obsession with detail. Security is not an upgrade – it is built into our process from the first drawing to the final install. Our windows are engineered to last a lifetime, both in durability and in beauty.
Approved for Grade 2 listed properties
Our security sash windows are the first and only in the UK to be officially approved for use in Grade 2 listed buildings – a milestone that reflects both authenticity and technical excellence.
Security is not a layer we add. It’s at the core of our patented EU construction. Beneath the hand-finished timber exterior lies a stainless steel inner framework – invisible from view, yet virtually impossible to breach. Designed to resist crowbar attacks and tested to withstand ballistic impact, our frames provide true vault-grade protection.
Our system holds multiple international patents, and our design meets the highest physical security standards for domestic and heritage buildings. While others may retrofit locks, we integrate secure thinking into every detail – including our patented fixed-position ventilation lock, which allows airflow without compromising safety.
The Sash Vault design allows our products to meet conservation requirements while delivering performance that far exceeds standard wooden sash windows. Whether it’s a period townhouse, a listed property, or a city residence, our frames are approved where others are refused.
We set the standard others try to meet
When it comes to protecting period homes, no other window system offers the balance of security, craftsmanship, and compliance that Sash Vault delivers. Here’s what sets us apart:
Others may offer sash windows with optional locks. We offer a complete security system, seamlessly disguised as period joinery. That’s why Sash Vault is trusted in homes where beauty matters – and safety is non-negotiable.
Hand-built sash windows with concealed steel interiors
Every Sash Vault window is bespoke. No templates. No shortcuts. We begin with your building’s character, period and layout. Then we craft a window that enhances it – in shape, in finish, and in function.
Our patented sash system is engineered with stainless steel internal structures, encased within Accoya or Medite Tricoya timber. These materials are selected for their extraordinary durability, dimensional stability, and resistance to moisture and decay. The result is a window that retains its form and function for decades, even in the harshest environments.
Choose any opening format – sliding from the top, bottom, or both. We accommodate every style: Georgian bars, curved tops, deep sills, or minimalist modern lines. Every unit is built to your exact measurements, including non-standard dimensions and arched or angled frames.
We offer a full range of glazing options: single, double, high UV-value, UV-reflective, laminated, and bulletproof. Whether your project calls for energy efficiency, heritage compliance, or ballistic protection, our glass units are matched to both your aesthetic and security needs.
Security is present even where you’d least expect it – including our secure ventilation feature. This patented lock allows the window to be held partially open in a fixed position, letting air circulate safely without inviting intrusion.
No off-the-shelf solutions. Every window is handcrafted, fitted to your building, and designed to perform for a lifetime.
From first measurement to final polish, we handle it all
Sash Vault offers a complete service – from the first site visit to the final fitting. We never outsource installation. Every window is installed by our in-house team, trained to our exacting standards.
We begin with a detailed professional survey. Our team visits your property, carries out precise measurements, and answers every question. We advise on security upgrades, architectural requirements, and even conservation constraints – ensuring the design we craft fits your building and complies with all regulations.
Installation is carefully scheduled around your needs. Our technicians arrive on time, work with clean and minimal disruption, and fit each window to the millimetre. We test all locking points, seals, and sliding mechanisms. Nothing is signed off until it performs perfectly.
Our reputation is built on long-term trust. That’s why we offer extended and, in some cases, lifetime warranties on both frame and function. If you ever need adjustments, advice, or servicing, we remain available – long after the final pane is fitted.
Every Sash Vault window is a precision product. And we ensure it’s installed with the same precision it was built with.
Honest answers. Clear guidance. No guesswork
Choosing high-security sash windows for your property can raise a number of questions – especially when listed-building approval, bespoke design, and specialist installation are involved. Below, we’ve gathered the most common queries from clients across the UK.
Whether you’re at the early planning stage or ready to request a survey, these answers will help you understand our process, products, and what to expect.
See the quality. Feel the weight. Test the locks
Our London showroom is open by appointment for private viewings. Here, you can experience our sash windows first-hand – see the materials, operate the sliding mechanism, feel the weight of the steel-reinforced core, and test our patented ventilation lock.
Whether you’re comparing glazing options, confirming heritage detailing, or simply want to feel the quality before making a decision – a showroom visit brings everything into focus.
We’ll walk you through the construction, security features, frame styles, glass types, and installation details. No pressure – just answers and insight from the people who design and build your windows.
59 Chalton St
London, NW1 1HY
Precision, advice, and a tailored quote
Every secure window begins with an accurate, professional assessment. At Sash Vault, we do not guess or generalise. We come to your property, listen carefully, and measure precisely. Our survey is led by experienced technicians who understand not only sash construction, but also the requirements of heritage homes and the realities of modern security.
During the visit, we assess your existing windows, note architectural constraints, and advise on frame design, opening styles, glass specifications, and finish options. If your home is listed, we guide you through conservation-compliant solutions. If security is your priority, we explain performance levels, material strength, and how our patented system protects where others cannot.
Following the visit, you receive a clear, tailored quotation. It includes every detail – design, construction, installation, timeframe. No assumptions. No pressure. Just everything you need to make a confident decision.
Whether you need one secure sash or a full-house installation, the process starts here – measured with precision, built around your property.
To receive a tailored quote or arrange a professional survey, please complete the form below. Our team will review your details and get in touch to discuss your requirements, answer any questions, and guide you through the next steps.
We don’t send automated estimates – every response is considered, precise, and based on your property’s needs.