QUALITY & SECURITY
Luxury appearance, fortified with patented internal structure
Security and craftsmanship are rarely found in the same frame. At Sash Vault, they are inseparable. Every window we build is designed to meet architectural heritage standards – and exceed modern expectations for protection.
We are not retrofitting extra locks. We are rethinking how a sash window can perform. From the outside, our frames appear completely traditional: fine timber finishes, balanced movement, heritage proportions. But inside, they hide a patented stainless steel core, engineered to resist physical attack and forced entry.
This balance of visible beauty and concealed strength is at the heart of everything we make. It’s why our windows are trusted by conservation officers, security consultants, and discerning homeowners alike.
We will guide you through what sets Sash Vault apart – from listed building approval to bulletproof options – and why no other sash window offers the same quality, security, and peace of mind.
Designed to meet the rules. Engineered to exceed expectations
Sash Vault is the only sash window system in the UK with formal approval for use in Grade 2 listed buildings. This unique status was earned through years of development, testing, and refinement – balancing conservation accuracy with concealed structural innovation.
Our windows are accepted by planning authorities and heritage consultants because they match original architectural detailing. From timber profiles to glazing bars, every visual element reflects the period. Nothing about the window’s appearance signals modern interference – and that’s exactly why it’s approved.
Behind the traditional look is a patented stainless steel structure. Hidden entirely within engineered timber, it offers a level of physical protection unseen in any standard conservation frame. This allows listed homeowners to meet planning regulations while securing their property with confidence.
Where other manufacturers face restrictions, refusals or compromises, Sash Vault is welcomed. We don’t work around regulations. We meet them head-on – and win.
A hidden stainless steel structure inside every window
At the core of every Sash Vault window lies a breakthrough in secure joinery – a patented construction system developed exclusively for properties where safety, strength, and discretion are non-negotiable.
Our design integrates a stainless steel framework completely concealed within engineered timber. This isn’t surface-level reinforcement. It’s structural. It forms the backbone of the window itself, bonded with timber components that retain full architectural authenticity.
This patented method is protected under EU intellectual property law, meaning no other manufacturer can replicate it. It’s a system we created, tested, and proved to outperform anything in its category – both in security performance and visual integrity.
The result is a sash window that functions and looks exactly as it should, but defends like no other. Intruders won’t see what’s behind the timber – and that’s exactly the point. Quiet, invisible strength, protecting what matters most.
Crowbar resistance, bulletproofing, and patented locks
Sash Vault windows are designed to defend against real-world threats – not just tick boxes. Every unit we build is constructed with security as a core function, not an added feature.
Our patented internal steel core has been tested to resist forced entry, including crowbar attack. This isn’t decorative security – it’s structural defence built into the frame itself. The system supports multi-point locking and concealed resistance zones, all while remaining invisible from the exterior.
For those requiring enhanced protection, our frames can be specified with bullet-resistant glazing, certified to withstand ballistic impact. This is particularly suited to high-risk properties, embassies, city residences, or anyone who values complete peace of mind.
We also include our patented secure ventilation lock as standard. It allows the window to remain slightly open, fixed in position – offering air circulation without compromising security.
No visible bars. No ugly reinforcements. Just clean, classic timber sash windows with exceptional strength inside. Approved by planners, trusted by professionals, and built to protect.
We select every material for strength, stability, and longevity
Our sash windows begin with premium materials selected for their stability, resilience and finish. We don’t use softwood. We don’t rely on surface treatments. Every component is chosen for a purpose – and built to perform for decades.
At the core is engineered timber: Accoya or Medite Tricoya, depending on the project. These are advanced, dimensionally stable woods designed to withstand moisture, temperature changes, and decay – without warping, shrinking or cracking over time.
Inside the frame sits our stainless steel reinforcement, precision-welded and bonded to provide a rigid, unyielding core. It’s this internal structure that gives Sash Vault its unique strength – and makes our windows suitable for high-risk environments while maintaining conservation approval.
Every window is handmade by skilled joiners. We cut, assemble, and finish in-house, ensuring consistent quality throughout. Finishes are refined. Details are sharp. Nothing feels mass-produced – because nothing is.
Our craftsmanship is visible in the timber, felt in the movement, and proven in the performance. This is British joinery, elevated by engineering – and built to last.
Made for listed buildings. Trusted by conservation officers
We understand the demands of heritage architecture. Sash Vault windows are designed to pass the closest visual scrutiny – whether from a planning officer, a conservation consultant, or an owner who knows their Georgian from their Edwardian.
Every visible element of our windows is true to period. From glazing bar profiles to timber joints, from putty lines to cord and weight detailing, we replicate the design language of traditional sash joinery with complete authenticity.
And yet, beneath that surface, everything is different. Our patented construction allows for full compliance with heritage restrictions, while discreetly housing stainless steel reinforcement, secure ventilation, and even ballistic glazing – all without affecting the window’s external appearance.
Unlike surface-retrofit systems, nothing we build looks modern, mechanical, or out of place. That’s why Sash Vault windows are accepted in Grade 2 listed buildings where others are refused.
If your property is sensitive, historic or under planning control – there is no safer, more appropriate choice.
Made to withstand British weather, time, and wear
Sash Vault windows are not designed for the next five years – they’re built for the next fifty. Every material, joint and finish is selected to ensure your windows remain strong, smooth-operating, and secure through decades of use.
We use engineered Accoya and Medite Tricoya, which outperform traditional hardwoods in dimensional stability. These timbers are resistant to rot, swelling, and shrinkage – meaning the windows hold their shape, seal properly, and slide effortlessly over time.
Our internal stainless steel structure is immune to corrosion, movement and fatigue. It keeps the sash rigid and secure, even under pressure, temperature shifts or humidity. Paired with high-spec glazing and modern seals, the result is a unit that resists both intrusion and deterioration.
Glazing options include UV-reflective, laminated, or bulletproof glass, all offering thermal stability and long-term clarity. Frames are finished to endure the British climate, with minimal maintenance required.
Many of our installations carry extended or lifetime warranties – a reflection of our confidence in both product and process.
This is protection that won’t loosen, fade, or fail. It’s the kind of quality you feel the first day – and still trust twenty years later.
Elegant, compliant, and quietly resistant
Great security doesn’t announce itself. It works in silence – quietly deterring, resisting, and protecting. That’s the essence of a Sash Vault window.
From the outside, you see a beautifully crafted timber sash. It fits your building, your period style, and your expectations of elegance. What you don’t see is the vault-grade stainless steel inside, the multi-point locks, the bulletproof glazing – or the fact that it’s the only sash window in the UK approved for Grade 2 listed buildings with these levels of protection built in.
We believe security should never interfere with beauty. And we prove it – every day, in properties where aesthetics matter as much as safety. No unsightly reinforcements. No compromise on sightlines or symmetry. Just the confidence of knowing you’ve chosen a window that guards without shouting.
With Sash Vault security windows, you don’t have to choose between protecting your home and preserving its character. You get both – in one seamless, silent, secure solution.
Visit our showroom and discover the system up close
Some things need to be seen – and felt – to be understood. That’s why we invite you to visit our London showroom by appointment.
Here, you’ll experience our windows first-hand. Run your hand over the timber. Slide the sash. Test the locks. See how the secure ventilation position works. Inspect the fine finishes. And most of all – witness the clean, traditional appearance that conceals the entire security system within.
We’ll walk you through our construction method, show glazing and timber samples, and answer all your questions – from heritage approvals to installation timelines.
Prefer us to come to you? No problem. You can also request a professional survey, and we’ll visit your property to assess your requirements, take precise measurements, and guide you through the process.
59 Chalton St
London, NW1 1HY