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Retrofitted Protection, Zero Compromise

Reinforce security without replacing original windows. Ideal for heritage properties or temporary use, these systems offer RC6 and FB7-NS protection while preserving exterior aesthetics.

Secondary Window Systems

Achieve high-level protection without replacing existing windows. SÄLZER’s secondary systems offer certified resistance to forced entry, ballistic attack, blasts, and fire—perfect for listed buildings or temporary security upgrades.

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Retrofit solution for enhanced security

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Maintains exterior building appearance

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Protection against burglary, bullets, and blasts

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Ideal for listed or architecturally sensitive buildings

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Optional fire and smoke resistance with steel options

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Compatible with S1es, S2es-w, S6es-w, and SECUFIRE® systems

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External or internal installation available

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Customisable finishes: powder coated, anodised, or timber clad

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Time-efficient and cost-effective upgrade

Upgrade Security Without Replacing Windows

Discreet, high-performance protection for retrofit and heritage applications.

SÄLZER’s secondary window systems provide a smart, non-invasive way to elevate building security. Designed for use with existing windows, they deliver robust protection against forced entry, bullet impact, and blast threats.

Whether installed internally or externally, these systems are ideal for high-security environments where aesthetics must be preserved—such as embassies, government buildings, and listed properties.

With optional integration of fire and smoke resistance (when using the SECUFIRE® steel system), this solution ensures compliance with even the most demanding project requirements—without the need for full window replacements.

Technical Specifications

Certified protection tailored to your existing architecture.

Forced Entry Resistance

Tested to DIN EN 1627–1630 standards. Levels vary based on selected system: S1es aluminium façade, S2es-w and S6es-w aluminium windows, SECUFIRE® steel systems.

Bullet Resistance

Certified to DIN EN 1522–1523 with glazing per DIN EN 1063. Achieves up to FB7-NS depending on selected system.

Blast Resistance

Tested with 500 kg of explosives at 24 m distance. Certified to GSA 2 and ISO B hazard levels.

Fire & Smoke Resistance

Available up to T90/EI90 and S200 classifications when SECUFIRE® steel frames are selected.

Installation Options

Can be mounted internally or externally on masonry, concrete or façade elements. Compatible with multiple SÄLZER systems.

Materials & Finishes

Available in aluminium or steel. Finishes include primed, painted, anodised, powder coated, or clad with timber, stone, or bronze.

Thermal & Acoustic Performance

Dependent on selected product series. Excellent insulation values possible with triple glazing and tight seal design.

Customisation

Each system tailored to site-specific needs including colour, dimensions, and integration of communication or access tech.

Retrofitting a Secure Solution?

Talk to Our Commercial Glazing Specialists

Get expert advice on integrating secondary window systems into your project. Maintain aesthetics while ensuring top-level protection.

What Our Customers Say

We take pride in delivering exceptional glazing solutions and outstanding customer service. Here’s what some of our happy clients have to say about working with Minimal Frame Projects.

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   Alison Burton 
 
 
 
  Absolutely delighted with our recent purchase of sliding doors for our new orangery, part of a major renovation of our home.  The quality is top-notch, and the sleek design will perfectly complement or modern kitchen and frame the amazing views we have. The door’s sturdy construction and beautiful minimalist finish add a touch of elegance to the space. Highly recommend this product to anyone looking to enhance their home with stylish and functional sliding doors.
  
 
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   James Trinder 
 
 
 
  Minimal Frames have been outstanding throughout the process, from planning to install and aftercare. At all times their communication has been top-notch; fast and effective. Quality of the glazing itself is excellent, the installation process was pain free and the windows and pivot door look incredible. They’ve been really strong on aftercare too, checking in that all works well and correcting a very minor issue quickly. I really cannot fault any part of our experience and wouldn’t hesitate to use them again and recommend to others.
  
 
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   Narmina Hasanova 
 
 
 
  Bob and his team have taken on our tricky glass extension installation, embraced its complexity and delivered it to perfection. It truly is a stunning addition to the house. The team that worked on site was extremely pleasant; always on time, quiet and polite. The project turned out to be long for its complexity, but the final result was worth the wait. We are very pleased with the outcome and hope it will keep us cool even in the heat of summer. Thank you MFP team! With kind regards, Emil and Narmina
  
 
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   Elliott Raggio 
 
 
 
  I am pleased to say that overall, I am delighted with the honorable customer service from Robert the company director at Minimal Frame Projects. Thank you to the surveyor and installation team who executed a challenging install for my bespoke Glass Pivot exterior door. Credit does go to Robert for being understanding, a man of his word and overcoming obstacles to ensure complete customer satisfaction.
  
 
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   Bruce Fraser 
 
 
 
  Ultimately an excellent result. Great product. Bob, Mollie and the team worked hard at solving problems and timing. We appreciated their effort and approach.
  
 
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   G B 
 
 
 
  Bob and Minimal Frame have stepped in to help sort out problems with another glazing company. He has kept us well informed throughout and has worked tirelessly to deal with the manunufacturers to get the doors delivered and the install started. We were 90% done by Christmas which was a huge relief. I've found Bob to be straightforward, transparent and responsive and am very grateful for his help fixing our previous issues. Additionally, his install team have been highly professional and meticulous in getting the install right.
  
 
  
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Visit Our Showroom in Surbiton

Visit Our Showroom & Explore Premium Glazing Solutions

Experience the quality of our slimline glass doors, windows, and structural glazing in person. Whether you're planning a project or need expert advice, our team is here to help.

Located in Surbiton, we welcome homeowners, architects, and developers to see our range up close.

Call 0207 550 6550