We love the simple elegance of sash windows. A quintessentially British classic that has meandered through time since the 16th century. In fact, we love them so much that we’ve created a cutting edge solution to protect their posterity while introducing modern standards of soundproofing and thermal insulation. Introducing: our secondary glazing for sash windows with noise reductions of up to 51dB.


Designed to be installed inside your current frames, our secondary glazing for sash windows is a top of the line soundproofing solution. Your original sashes remain untouched, while our hight performing secondary glazing creates a highly effective sound barrier inside your property. Slender, discreet and efficient, they are perfectly suited to homes in conservation areas and Grade II listed buildings.


Our secondary sash glazing isn’t a one size fits all solution. We have a wide range of glazing, frame and soundproofing options for you to choose from. Starting at 38dB, all the way up to our triple glazed 51dB unit, our secondary glazing can come fixed, or with casement and tilt and turn openings.

Of course, we’ll also make recommendations based on our sound survey to ensure you’re getting the right product for your property.


We create fully customised glazing depending on how you want the window to function and the space that you have available.


Side-hinged and tilt and turn, all of our secondary glazing for sash windows is installed with high performance seals to stop noise flanking around the frame.


Our easy-open design is made for optimal usability, allowing you to access the existing sash for maintenance, repairs and to improve ventilation.


A sturdy multi-stage locking system allows for micro ventilation without compromising safety and security, as can be the case with an open sash.


Many of our secondary glazing for sash windows are installed in listed buildings and conservation areas. In other words, properties where preservation is paramount.

In addition to the secondary glazing, we can craft and install bespoke panelling, architraves, boxing and more, to ensure the seamless integration of our system within the existing design scheme.


Our secondary glazing for sash windows is the ultimate solution to noise pollution. Enabling you to keep your authentic sashes, while also benefiting from modern levels of thermal comfort.

Our secondary glazing units have a maximum Ug-value of 0.6 W/m²K, meaning that all of our systems are ultra energy efficient.


All of our secondary glazing systems for sash windows are made to order and, as you know, perfection takes time. Before manufacturing begins, we need to survey your property, which will be scheduled in the first couple of weeks. From the time the order is placed until installation generally takes between 10-12 weeks.


We want to help you find the right product that suits you, so whether you want to talk to us about our secondary glazing systems for sash windows, we’re here to help.


  1. What is secondary glazing?

    Secondary glazing, often known secondary glazing systems, are discreet window units that are installed on the inside of your existing sash windows. By creating another barrier, they improve the thermal efficiency of a property while reducing noise pollution. There are a wide variety of secondary glazing systems available on the market. At The Soundproof Windows we create bespoke secondary glazing systems for sash and casement windows. These are custom built to tackle our clients’ specific needs.

  2. How much does acoustic glass cost?

    Secondary glazing is a highly effective solution to noise pollution and heat loss. It is especially useful in properties where you cannot change your existing sash windows, for instance in a listed building, a conservation area or if you are living in a flat inside a larger building.

  3. Can secondary glazing be installed in listed buildings?

    Yes. Secondary glazing can be installed in almost all Grade II listed buildings and other buildings in conservation areas. We work with you and your architects to ensure that all standards are met.

  4. How effective is secondary glazing?

    Our secondary glazing for sash windows boast noise reductions of up to 51dB, and are rated A+ and over for thermal efficiency.

  5. Is secondary glazing as good as double glazing?

    As a general rule, yes, but it depends on the secondary glazing system. At the Soundproof Windows, our secondary glazing far outshines the performance of standard double glazing. This is because we employ the finest soundproofing techniques and technologies to ensure optimal performance.

  6. How do you install secondary glazing?

    Secondary glazing is installed inside the existing sash window. It is installed so that it does not affect or alter the existing glazing. We also craft and install additional design elements such as architraves and trims to ensure authenticity is preserved.



All of our products come with up to a 10 Year Insurance Backed Guarantee provided by the Consumer Protection Association. So you can rest assured that your home is in safe hands.



We have been Trading Standards Approved and are proud to be enrolled on the Buy With Confidence Scheme, ensuring customers just like you have their interests protected.

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Consumers can feel confident using a TrustMark registered business, as the government-endorsed scheme ensures high quality service and a range of consumer protection options.