Born in the Georgian era, the fabulously simple design of sash windows have been modernised to produce slimline, soundproof designs. With tested reductions up to 44dB (best on the market), you can practically mute the drone of planes, trains and automobiles.

The window of the inner city, sash frames are the perfect solution for spatial optimisation. By simply sliding up and down, you needn’t compromise on sill space with this sleek and smooth self contained unit.

The Science of Soundproof Sash

With the minutest details examined and reexamined, these are windows designed for moderate to high noise pollution. There are two main ways in which these double-glazed soundproof sash windows work to reduce noise in your home.

Noise Reduction Glass

All sounds oscillate at set frequencies, and in order to dampen them, you need to confuse the wave pattern so that is dissipated rather than entering your home.

By using two slightly different thicknesses of glass, according to your specific noise source, soundproof sash windows break up the soundwave, stopping it dead in its tracks.

Spring & Box

Traditionally the spring box and weight and pulley mechanism which controls the window function would act like an acoustic guitar, amplifying the sound. Here the box has been redesigned to get rid of any unnecessary dead space, and fitted with dampening materials to further reduce noise pollution.



up to 40dB

Recommended For: Moderate to high noise pollution. Box Depth: 165mm


up to 43dB

Recommended For: High levels of noise pollution. Box Depth: 165mm


up to 47dB

Recommended For: High to severe levels of noise pollution. Box Depth: 189mm


Product Options


  • Specialist Noise reduction glass –  43dB, 45dB, 47dB, 50dB
  • Obscure glass
  • Safe glass


  • Traditional weight and pulley
  • Modern spring box


To complete the look, we offer a range of traditional accessories and ironmongery options for you to choose from.




The glazing inside your existing window can be replaced with high performance noise reduction glass. However, if the window is not properly treated, this will be ineffective and will still let sound in.


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A mid-range option, secondary glazing offers significant reductions in noise pollution, however, these windows are considered aesthetically poor due to the fact that they completely steal windowsill space.


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Made to fit, these specialist noise reduction sash windows are equipped with top of the range noise reduction glass. Designed to specifically deal with noise pollution, these are on the high end of the price range.


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The inner city classic has had a modern makeover. With our soundproof sash, maintain all the elegance of the timeless sliding frame design while benefiting from tested reductions of up to 44dB.

It may seem that with such a small difference in noise reduction that the windows should be similarly priced. However, the decibel scale is a logarithmic scale with base 10, which means each increase of 10 units (say 30 to 40 decibels) actually means a power increase of 1000%..

As such, scaling from 38 to 40dB requires more refined technology (which itself required far more research time), and materials better equipped to reduce noise pollution in your home. The results are considerably audible, and we recommend higher-end products only to those whose budget allows for them, or whose noise complaints demand them.

The prices displayed below do not include VAT and installation costs.


43dB Double Acoustic Glazing

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43dB Double Acoustic Glazing

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43dB Double Acoustic Glazing

Price From:


Soundproof conservation sash windows in teal


Our sash windows for conservation areas have had every little detail examined and tweaked. From the way that the locks clasp in place, to the foams used at installation, they are reflections of the latest technology and finest craftsmanship. We know how much of a pain it can be to get planning permission for properties in conservation areas. That’s why we’ve got a whole range of soundproof conservation sash windows, designed to mimic your traditional frames. Maintaining that timeless aesthetic, you can now benefit from incredible reductions in sound while also boosting thermal efficiency. Here’s how it works.


Our in-house experts will talk you through your options, and conduct an on-site sound and design survey to find the right product for your property.


We support you through the whole planning permission process and work closely with surveyors to ensure your case is as strong as possible.


All of our replacement sash windows for conservation areas are custom made to be as close in design, finish and installation to your current windows.


  1. How effective are your acoustic sash windows?

    Our acoustic sash windows go up to 47dB in our Ultra range – that’s the best you’ll find on the market. Our Soundproof and Soundproof+ ranges go up to 40dB and 43dB respectively. But it’s not just our windows that stop sound coming in.Our installation process has been finely tweaked to ensure the best possible results. From using acoustic sealants and tapes, to isolating the window from the wall, our expert installers have been highly trained to prevent any air gaps that sound could get through.It is important to note that your windows will only be as effective as your property itself. If you have noisy air vents, chimneys or other entry points for sound, you will still suffer from noise pollution.

  2. Can your acoustic sash windows be installed in conservation areas?

    We have bespoke heritage and conservation ranges designed to be installed in properties in conservation areas. Crafted to look like your pre-existing windows, we can match any paint finish, as well as replicating fine detailing. You get to retain the aesthetic of your property, while benefiting from much improved modern noise reduction.If you are unsure whether you need to get planning permission to install new windows in your home, we are happy to give you free, impartial advice.

  3. Do I need secondary glazing to soundproof my sash windows?

    No. Our soundproof sash windows have been designed and acoustically tested to prevent noise pollution getting into your home. We have spent years in research and development to provide the market-leading soundproof sash, reducing noise by up to 47dB. Finely crafted to keep the authentic look of your home, these windows will address most moderate to high noise complaints.That said, the design of a sash window does not allow for the same level of noise reduction as our other windows. You see, with a multi-point locking mechanism, and whole-window seal system, we can boast reductions of up to 51dB in our casement, tilt and turn, and secondary windows.If you have the cill space to accommodate, and the noise complaint is severe, we do recommend installing secondary glazing instead of simply replacing your sash windows. This is not as aesthetically pleasing as retaining your original style window, but will dramatically increase noise reduction.

  4. Can I install acoustic glass in my sash windows?

    It is possible to install acoustic glass within your existing sash windows, but there are three key things to bear in mind:- Acoustic glass tends to be a lot heavier than standard glazing. This will put considerable strain on your existing window frames and can lead to failure.- Acoustic glass is also a lot thicker than standard glazing (single glazing is ~4mm, acoustic glazing tends to be a minimum of ~15mm), meaning older sash windows are unlikely to be able to accommodate acoustic glass.- The performance of acoustic glass is only as good as the window it is fitted in. If the window itself hasn’t been acoustically treated, installing acoustic glass will be pointless.

  5. Can you replace windows in a grade 2 listed building?

    Yes, but you will need to get planning consent before you carry out the installation. To replace single glazed windows with double glazed, you will need to install narrow profile units such as our Heritage Soundproof Sash range. In many cases, it will be easier and more effective to install secondary glazing inside the existing window.

  6. How do you maintain a sash window?

    Our sash windows are manufactured with engineered timber. This ensures that the wood will not swell or shrink over time, and requires very little maintenance. That said, there are a few simple steps you can take to ensure the longevity and beauty of your windows:- Use non-abrasive soaps and a little warm water to clean the frame of your windows when required.- Open your windows every so often to ensure there has been no build up of gunk that can cause them to stick in place.- Regularly inspect your windows for any faults that develop. If they are covered by our guarantees, we will be happy to come and repair them at your convenience.

  7. What is secondary glazing for sash windows?

    Secondary glazing for sash windows requires placing a window frame and glazing on the inside of the pre-existing unit. For most secondary glazing solutions, there should be at least a 100mm gap between the two windows. However, with our high performance secondary window, we only need a 5-10mm due to their advanced locking and seal systems. A two glazing system will dramatically reduce noise when compared to standard sash windows.


We’d rather help you find the right product than just any old product. So whether you want to talk to us about our soundproof casement windows, or simply about how noise reduction windows work, we’ll be glad to help.


Trees for Life is a conservation charity dedicated to rewilding the Scottish Highlands. They currently have 44 tree planting sites and have planted nearly two million trees to date.



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.



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.



Following awards in 2020, and 2021, The Soundproof Windows was announced as the ‘Best Acoustic Window & Door Installation Company – London’ at the SME News Awards 2022.