Category: Technology

Noise Reducing Glazing – A Guide

Improvements in manufacturing techniques have not only made noise-reducing glazing much more efficient at cancelling noise but also considerably more cost-effective than you might imagine making it possible to significantly reduce noise through windows.

A specialized glazing system, also occasionally referred to as acoustic glass, it is used in pre-fitted systems and can also be installed in existing window frames. Due to its physical properties, ‘normal’ glass is an extremely efficient conductor of sound, great for keeping out wind and rain but of little value as an insulator against noise.


The science behind soundproof glazing is relatively simple. The requirement for noise-cancelling windows is obviously to prevent as much sound as possible from penetrating the glass but reducing noise from windows is not the only factor, there are four other major contributory factors that affect this.

The thickness of the glass, the quality of the glass, the space between glass panes and the sound dampening elements contained in the interlayers.

There is also a fifth element to consider, the quality of the fitting.


Thickness – It seems obvious that the thicker the glass, the greater the soundproofing will be, but this is not always the case. Sometimes two sheets of glass of an identical thickness will actually amplify sound rather than reduce it.

glass thickness

You can read all about the science behind the properties of sound here

Quality – Hugo Carter fit the very finest noise reducing glass from market leaders Pilkington and Saint Gobain to achieve truly remarkable results.

Spacing – The correct distance between the sheets of glass is guaranteed by our engineers. Factors taken into consideration include available space, noise reduction requirements and budget. Too much space between the sheets and the windows, while efficient, may be too wide for fitting, too little space and noise cancelling efficiency is lost.

glass spacing

Interlayers – These are used for sound dampening windows. Depending upon the type of unit and the noise cancelling requirement, consideration is given to the use of inert gases such as argon and krypton. As ever, Hugo Carter will advise on the most appropriate for your requirement.

Fitting – Here at Hugo Carter we have developed a system that is unique to us, our sash and casement windows feature an engineered solution that we ourselves have developed to achieve astonishing noise reduction without compromising on the finished look.

Thermal Efficiency

We often focus on the noise reducing capabilities of our glazing products and of course, this is a major consideration for our clients. We should not however, overlook the cost-savings available as a result of fitting Hugo Carter sound proof windows.

Our units are designed to be fully insulated, cold air cannot get in and warm air cannot get out because there are no gaps between frame and glazing. The inner pane of glass is ‘soft-coated’ which means it reflects the heat back to the room to further improve thermal efficiency. From an environmental and financial perspective, this means that you will not be paying to heat your garden or the street outside.

Thermal Efficiency is measured by calculating the proportion of light allowed through the glass, the measure of heat loss and the percentage of solar radiant heat allowed through the glass.

The important part is that every unit is given a rating between A and F or 1-6 based on these efficiencies and as we hope you would imagine, Hugo Carter are experts in efficiency.


glass thermal efficiency

Safety and Security

The effectiveness of high-quality glazing as a security feature cannot be overlooked and Hugo Carter install windows and doors that property owners can rely upon to act as an efficient barrier. Safety advisors will always suggest that glazed units should feature glass that will not shatter on impact and this is true of every unit we fit.

More importantly, the added benefit of laminated glazing is security. Windows equipped with such glazing are much harder to break into.


Interior uses

Noise reducing glazing can be used effectively in-home or office environments to separate rooms and workspaces, more aesthetically pleasing than a wall and offering more light while maintaining acoustic integrity. Hugo Carter install soundproof internal windows and also soundproof internal doors.


Our website features a number of articles about the applications of acoustic secondary glazing and acoustic glass including its suitability for use in listed buildings. If you have any specific questions or general enquiries, please call or email and we will be pleased to offer help and advice.

Soundproof Windows versus Secondary Glazing, a Few Facts

Noise is something that many of us accept to live with, a normal part of everyday life in the modern world.

The city dweller may become almost immune to the roar of traffic, the revving of a passing engine, the annoying buzz of a moped. Country living too is not without its noise, perhaps a passing aircraft or maybe the sound of church bells just a little too early on a Sunday morning?

Sometimes, of course, we want to hear the noise, the happy sounds of a vibrant city or unhurried rural life going on outside our window. But as we all know, what we find delightful one day may become irritating beyond belief the next, the difference between children playing happily or sounding like shrieking little monsters is really all about how we are feeling at the time.

You need to be in control of the sounds in your life and thankfully, here at Hugo Carter, we can help.

So what is the difference between soundproof windows and secondary glazing? Well, we promised you facts so here are a few…

Secondary glazing works by fitting an additional pane of glass behind existing windows within the reveal or directly on the window frame. Typically, this additional single pane of glass will sit in aluminium channels and if there is enough space within the reveal the distance between the existing window and secondary glazing can be adjusted to optimise noise reduction.

Soundproof windows are designed with noise reduction in mind and in most of the cases eliminate the need of having the secondary glazing. Glass in such windows has been replaced with acoustic double glazing which outperforms the noise reduction of secondary glazing in the majority of the situations.


Noise Reduction

As you would imagine, soundproof windows win hands down in this category. Laminated double glazing dulls sound waves and the space between the panes is optimised for maximum noise reduction. Flexible silicone between glass and timber frame also ensure there is little or no vibrations being passed onto the frames.

Secondary glazing can also help to reduce noise by creating an additional barrier between the outside world and the building interior. For obvious reasons the noise reduction will not be as dramatic as with soundproof glazing but you will undoubtedly notice a difference after fitting.



To speak candidly, this is one area where secondary is much more straightforward than soundproof.

Soundproofing requires the removal of existing frames, we can, of course, match the look of the old frames and our craftsmen work quickly, without compromise on quality.

On the other hand, the fitting of secondary glazing is not beyond even the most inexperienced DIY’er, however, we would always recommend the use of a skilled handyman just to make sure.


Thermal Insulation

Both solutions will help in this respect, there is an inevitable difference in the efficiency of the two methods but secondary glazing is an awful lot better than nothing.

The pocket of air between the window and the secondary glazing creates an additional buffer between outside and in, helping to reduce heat loss but not the condensation!

Soundproof windows use a similar principle but in a far more effective way. These units are designed to be fully insulated, cold air cannot get in and warm air cannot get out because there are no gaps between frame and glazing. From an environmental and financial perspective, this means that you will not be paying to heat your garden or the street outside and eliminate the condensation effect.



Another clear victory for the soundproof windows.

Because of its design and the way it is fitted, secondary double glazing can cause a great deal of condensation. This will cause a build up on the primary glazing unit and often requires the temporary removal of the secondary to make cleaning possible.

Soundproof windows offer a single, air-tight unit so there are never any issues with cleaning or maintenance.



While soundproof windows have all the functional benefits of normal windows, secondary glazing due to its nature sits behind existing window limiting the access to it. Therefore, it isn’t very practical, especially after a few seasons, when its mechanism tops working efficiently.



Secondary glazing is considered a temporary solution and its lifespan is relatively short compared to soundproof windows. It’s short life expectancy is being justified with much lower cost.



It will come as no great surprise to learn that the professional installation of soundproof glazing is more expensive than secondary glazing.

Budgetary constraints can mean that the cheaper option makes sense and it would be disingenuous of us to suggest that secondary glazing does not work. It can make a genuine difference to noise reduction and even help a little with thermal insulation.

Soundproof windows will add value to your home and save money on energy bills but be under no illusion that they are anything other than a considered purchase. Hugo Carter takes pride in working to budgets and we provide detailed costings with every step of the way.



There is also the question of aesthetics. Majority of our customers dislike the secondary glazing for its ugly look more than impracticality. It is difficult to disagree. Timber soundproof windows offer much better looks and definitely score, more points in this category.


Any Issues?

The installation of soundproof windows and frames in some properties can require planning permission. We can help advise you on this and help guide you through the permission process if required.

Secondary glazing requires no consent and can be fitted in a matter of minutes.


…and the winner is


Well, we would say this, wouldn’t we? It has to be Soundproof Windows. They are designed beautifully to do their job properly, there is a place for secondary glazing but in our opinion that place is… second.


Interested in our Definitive Guide To Soundproofing Your Home? Check it out here. 

Listed buildings and architectural glazing

As the owner of a listed building of whatever Grade, you will be completely aware of the challenges surrounding any sort of change.

Here at Hugo Carter we know the joys and frustrations that can be involved with developing a listed building more than anyone else and you will be pleased to learn that with our experience in these matters, we really can help.

So, let us begin with a few words about listed buildings, what they are and why they are such a wonderful part of our architectural and cultural heritage.


Listed Buildings, a few facts…

Listing celebrates and protects buildings of a significant architectural or historic nature, they do not have to be old buildings but all those constructed before 1700 and surviving in a recognisable original condition are automatically listed. Most buildings constructed between 1700 and 1840 are also listed and while anybody can apply for a ‘modern’ building to be listed, a general rule of thumb is that it should be more than 30 years old.

There are regulatory conditions set for each part of the United Kingdom, Historic England for example are currently prioritising post-modern buildings and post war public houses. The latter is a perfect example of the authority recognising dwindling numbers of such buildings and acting appropriately to preserve them for future generations. Obviously, not all will continue to operate as pubs but they will still retain the architectural features typical of this style of building.

There are three grades of listed buildings

Grade I – buildings of exceptional interest

Grade II – buildings of more than special but less than exceptional interest

Grade III – Buildings of special interest.

Listing does not mean that changes cannot be made, it simply identifies buildings where historical and architectural value should be very carefully considered before planning decisions are made.


Conservation Areas…

Buildings in a conservation area are not the same as listed buildings, however they are often subject to similar development and restrictions to change. We always advise talking to an expert before making any changes. Of course, we believe that the expert should be us and we are always happy to offer completely impartial, no-obligation advice.

We have written a separate blog about glazing options for Conservation Areas and you can see it here


A special word about windows…

Of course, here at Hugo Carter we have a specific interest in windows so let us take a look at what can be done in this area.


We are often asked the very simple question, Am I allowed to change the windows in my listed building?

As with many simple questions, the answer is far from straightforward.

Listing does not mean that you are not allowed to make changes, it does mean however and we must be very clear on this point, you need to apply for permission to make changes before any work can commence. We can help with the application process of course and while we hold no guaranteed influence we are able to ask the right questions and make salient points on your behalf.

Proceeding with work before permission has been granted is a criminal offence, you might be prosecuted and may be liable for all costs in returning the feature to its original condition.

It is true that Grade III buildings are considered as more likely to receive consent to make change but it is highly unlikely that permission will be given for windows that could be repaired rather than replaced. Our experienced technicians will be able to confirm whether your windows need to be replaced or can be repaired.

You can find out more about upgrading to double glazing in a conservation area or in a listed building here.

Repair or Replace…

The first step is to meet with one of our technicians, usually on site. We will then have a clearer idea of what permissions you require and how we can best help to guide you through the process.

We work directly with architects, local authorities, council planning departments and fellow construction experts to make sure that no detail is overlooked. There are many factors to consider and we use all of our experience and resources to make sure that you end up with the best possible results.

One guarantee that we always make is that we will never recommend replacement windows where a repair would be more appropriate, but for those windows that do require soundproof replacement windows, you can count on our skilled craftsmen to ensure a precise replica.

Our factory is fitted with state of the art machinery and our skilled craftsman are ready to build precise replicas of your existing windows to meet conservation requirements.

Owning or managing a listed building is a wonderful privilege and so is the opportunity to work on such magnificent buildings. Here at Hugo Carter we recognize not only our duty to our clients but also our responsibility to future generations, we love listed buildings.

When it comes to constructing noise reduction windows and doors, there are certain things we won’t touch with a bargepole.

(Not even a fine oak bargepole.)

We’re talking about ‘hollow’ materials such as aluminium and UPVC that ‘leak’ noise and are highly unlikely to last you a lifetime.

By contrast, what we insist on building with, is good old-fashioned timber. And not just any timber, but hardwood timber, the construction timber of choice for centuries and visible all over the country – from manor houses and cottages to churches.

So why always hardwood timber? We could give you countless reasons why; here are three.

Reason #1: Perfect for soundproofing and insulating.

Hardwoods are exceptionally strong and durable – far more so than softwoods – as they come from slow-growing, broad-leaved trees. Thanks to its thousands of tiny air chambers per cubic inch, it holds in heat making hardwood an excellent insulator.

Reason #2: Beautifully easy to maintain.

One main advantage of hardwood is that it is very easy to maintain and clean. Any scratches or dents in hardwoods can easily be fixed by sanding, varnishing and waxing to restore its beauty, rather than having to replace the damaged area.

Reason #3: Beautiful on the eye.

Aesthetics are integral to how we work. And we love the way that hardwoods can be used with any type of style or décor because of the wide range of appearances they bring, and the fact they are available in a whole host of natural colours, depending on species chosen.

Yes –  there are countless other reasons for choosing hardwoods – like their exceptional value. You will find less expensive timber options – but you get what you pay for. So think of it as an investment. Whenever you use hardwood timber, it is likely to increase the value of a property.

And let’s throw another question into the mix, for good measure: “Why is the quietest place on earth so noisy?”

In our pursuit of creating a tranquillity that transforms, we do have some memorable ‘aha’ moments. Such as? When we realised that it’s actually possible to have ‘too much’ quiet.

… and that there’s a place so silent that the background noise measured is actually in negative decibels, -9.4 dBA.

So where on earth is the quietest place on earth?

According to our good friends at the Institute of Acoustics, it’s the anechoic chamber at Orfield Laboratories in Minnesota.


It is so quiet that the longest anybody has been able to bear it is 45 minutes.

When it’s that quiet, your ears adapt. And the quieter the room, the more things you hear… like your heart beating or your stomach gurgling loudly. According to the lab’s founder, Steven Orfield, “In the anechoic chamber, you become the sound.”

Yes, NASA has sent astronauts here to help them adapt to the silence of space. And us? When we talk about creating ‘the quietest spaces in the noisiest places’ we know where to draw the line.

Some words we hear so often that they become meaningless. Others are used in so many different ways, their exact meaning is unclear.

So – right now – let’s be clear exactly what we mean when we say we offer ‘bespoke’ windows.

Every single one of our windows is unique. And it isn’t just ‘made to measure’.  It’s measured to the millimetre before we use those measurements to engineer a window that fits your home perfectly.

And it’s not just the physical space we measure.

It’s also the noise levels.

Before we create your windows, there are always two kinds of understanding we need.

> On the one hand, we need to understand exactly what you need. In terms of aesthetics, in terms of noise reduction. So we can be certain that what we’re about to create for you will meet your expectations.

> On the other hand, we need to understand exactly how to translate those needs into windows that will help to transform your home or your hotel. And to that end, we’ve developed a unique design process.

And because we never outsource to anyone else, our end-to-end involvement means that there’s a continuity to that in-depth understanding – it runs right through our process. 

You could say, there are no gaps in our understanding… and also no ‘gaps’ in your windows. (We use a special silicon that helps ensure that, and that prevents any ‘rattle’ in the glass.)

So, there’s bespoke and there’s bespoke. If you want a made-to-the-millimetre window that is the perfect match for your needs, you know who to contact.

The detail we go into at the start leads to windows that are designed to delight.

But don’t take our word for it. Hear what our clients say here.