Soundproof Windows versus Secondary Glazing, a Few Facts

March 12th, 2018

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 aluminum 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 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 a normal window, 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 are relatively short compared to soundproof windows. Its 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 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.

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