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insulation sound proofing draught proofing stop condensation
ExtraGlaze contact details
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Extraglaze Explained
Measuring Guidelines
Solutions for listed buildings
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  • 2 months ago
    ratings 4
    Seems a good product and blends in very well with our decor.
    I had internet quote which was straightforward with good tips and advise on the measuring. Felt confident when I sent it that it would be ok.
    I sent for quote as diy and fitted by extra glaze and my only thought was that their quote for fitting sounded quite high.
    Thank you Lee for the positive feedback. It is true that the labour cost of our Fitted by Us service can be quite high. This is dependent largely on the distance from our nearest fitter and whether the work can be done in one or a series of days that might include overnight stays, etc. Just like we...
    lee rogers, Stoke-on-Trent
  • 3 months ago
    ratings 5
    Narrowboat Aslan
    Ease of ordering, telephone assistance where required and prompt delivery
    Product : Very easy to order, very easy to install that gives a professional look whilst using just DIY skills
  • 4 months ago
    ratings 5
    Excellent, friendly and professional!
    Excellent, professional and responsive. Very happy with the work done!
    Product : Fantastic professional service! I recommend them to everyone!
  • 4 months ago
    ratings 5
    What a difference!! No more cold blasts when you pass the windows.
    Very nice chap from Extraglaze fitted the product to my very draughty sash windows. The price did come up a little more than the on line pricing tool but nothing is perfect. Very clean and tidy workmanship and completed within the agreen time scale.
    Product : Very discrete panels...
    Mandy McDermott, Rossett Wrexham
  • 6 months ago
    ratings 5
    Cannot recommend highly enough - superb service and standard
    First class - I made a mistake on my measuring and Nic and his team could not have been more accommodating. Glazing is now in place and looks superb. The white border on both glazing and inner magnet (ensuring it still looks discreet in summer when the glazing is removed) is very good...
    Sarah L

Extreme Adhesive Test



We wanted to prove to ourselves our adhesive is as good as if not the best!

Proven to improve


coventry university logo bre logo


The Building Research Establishment and Coventry University complete tests of the Extraglaze system
Soundproofing and thermal test results...


Recommended for Listed Buildings


Telford and Wrekin Conservation Department encourage the use of secondary glazing, where possible, to increase thermal efficiency.


Solutions for listed buildings

Examples of bespoke Extraglaze solutions for listed buildings

While we'd love to say that we have developed our product for English Heritage, or for the Institute of Historic Building Conservation (IHBC), we actually develop Extraglaze for each and every client, just whenever we are asked to. And, as we do this, nothing does us more proud than receiving some approving looks or blatant praise from a local Conservation Officer. Quite simply we take great enjoyment from solving your secondary glazing challenges!

On this page you will read about just a few of those that presented themselves in listed buildings. In each case we developed several ideas, in our heads, on paper or with prototypes before agreeing with the customer exactly how to proceed, and ultimately solved difficult problems. In at least three of the examples here a Conservation Officer was party to discussions before work started, and vetted the end result – to the delight of our clients!

Example 1: A client with a 16th Century Farmhouse with original timber mullioned windows on the northern side with glazing (identified in an English Heritage book) commissioned Extraglaze to provide magnetic secondary glazing. A magnetic panel was developed to disappear into a distorted oak frame, with a draft excluder on the bottom edge to avoid adding an additional room facing surface along the sill. We also developed panels with two new choices of oak effect vinyl edge sourced exclusively for this client.

Example 2: A client with a Grade 2 Listed black and white half timbered detached house built in 1580. This commission was particularly challenging since some of the windows were dramatically trapezoid. For this building a magnetic panel was developed to disappear into the distorted oak frame using a veneer instead of vinyl. Sliding panels were also developed incorporating magnets which were a new and bespoke development peculiar to this building.

Example 3: A client with a Regency listed building with original panel single pane sash windows and a first floor door to a balcony. Extraglaze worked with the local Conservation Officer and gained approval for secondary glazing which took into account the distortions to all windows, ensuring maximum sound and heat insulation. The glazing was developed specially for this building and offered a higher level of sound proofing than a standard Extraglaze installation.

Example 4: A client with an apartment in a grade 2 listed converted Victorian coach house with three large wood framed windows. Extraglaze developed a magnetic panel to work around an extractor fan and still be invisible. As the panels to be installed were very large and exposed to the full force of the summer sunshine for prolonged periods, Extraglaze, through various trials, also changed their adhesive and developed their installation methods to solve problems that presented themselves on this job.

References are available from these and other satisfied clients. Please contact us either by e-mail or telephone.

How do I sound proof my windows?

How do I sound proof my windows?
In a nutshell... fit secondary glazing. It will provide more sound proofing than any other remedy (short of bricking up your windows).

Understanding the problems (and the design factors)

Secondary glazing is a very effective sound proofing measure. In comparison, double glazing and triple glazing are not. Even so-called “acoustic glass” is of little benefit compared to standard glass.

Secondary glazing can certainly reduce noise, significantly. Though it also depends on the following (this is not an exhaustive list):
  • type of noise. For example road noise is readily cured, aircraft noise is not. They differ significantly in frequency and energy
  • how far the windows are from the source. For example traffic/lorries driving past only a few feet away, because there is no front garden
  • full-on sound. For example street noises may be bouncing back & forth amongst close-knit buildings in a narrow town centre.
  • how thick the walls are. Bay windows are often thinner than the main walls, letting in extra sound.

Predominantly the effectiveness of your sound proofing measures is a factor of:
  • how well the existing windows are already sealed. If your windows are draughty then secondary glazing will seal them, and make a huge difference
  • how much gap distance you can achieve between the existing and the new glazing: the more the better
  • your room - it'll be much, much better for having: a carpet or substantial rug; soft furnishings; curtains instead of blinds; no piano (!)
  • Note too: choose secondary glazing with smaller panels in strong frames i.e. the stiffness helps.

Is double glazing or triple glazing better?

Double glazing and triple glazing will certainly let you down dramatically on the sound proofing (it’s little or no better than well-sealed single glazing in this respect)*. We've achieved as much as 75% reduction of noise after fitting secondary glazing.
*One customer came to us for help. She had recently purchased large triple glazed, PVCu bay windows, at considerable expense, for her lounge and main bedroom. They were just as noisy as, if not worse than, the windows they replaced. We designed and built a new solution just for her, with a 60mm gap between the inner glass of the triple glazed windows and our Extraglaze. Now she can barely hear the buses passing the end of her front garden. The thin dwarf walls of the bay do let some sound through, but we only noticed it because we are fussy.

Magnetic secondary glazing v's aluminium framed secondary glazing
With either system it is common to look out of your window to watch cars drive past and not hear them. Both systems are good for sound proofing. Aluminium frames can, but not always, look a bit like windows installed on top of your existing windows. Whereas Extraglaze magnetic secondary glazing can be genuinely inconspicuous. 
This is typically installed straight on to your existing window frame. On casement windows this usually achieves a gap less of 40 to 50mm. On a sash window it will achieve a gap of about 50mm on the lower half, and 125mm on the upper half. For even better sound proofing you need to add more gap, by adding a very slender superficial frame, to provide surfaces for the magnets to adhere to. The magnets make an excellent seal.
Aluminium Framed
If you have thick walls and therefore a deep reveal, then aluminium frames lend themselves to being fitted further away from the existing window i.e. for the best achievable gap. A superficial timber sub frame is necessary, unless you are offered a “reveal-fix” method. Unfortunately doing it this way “eats up” your available window sill.  This and the prominence of the frames may be unsightly to you. With a large gap (about 125mm or more) an excellent result is achieved - providing the system you have installed also makes an excellent seal.

Acoustic glass
You can consider having acoustic glass in your windows. It will be very expensive. If you were able to stand in your room with acoustic glass and instantly switch to non-acoustic glass you would be exceptionally lucky to have ears that can tell the difference. Special machines that measure in decibels can record the difference. Architects specify acoustic glass even when the improvement it makes is very small indeed. Of course it will depend on other factors too, such as the frequencies of the noises outside, and the thicknesses of the glazing in the window sandwich. If you have it installed as secondary glazing then make sure it is a different thickness to the existing glass.

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Some quotes from Extraglaze customers:
“I have installed Extraglaze panels on 11 sash window in a grade two listed building dating back to 1799. I feel this is a great success. They are unobtrusive, very effective at reducing noise, good at reducing condensation and help enormously with heat insulation.”
“On a rating of 0 to 5, we would give the Extraglaze panels that you made and installed for us a rating of 5 for making our house warmer, 5 for reducing noise and 5 for the pleasing appearance of our windows. We were equally pleased with your modest pricing of our Extraglaze panels. We had almost given up hope of finding double or secondary glazing that would give us all these benefits and still enable us to retain the lovely original glass in the windows of our hundred-year-old house - until you were referred to us. We are simply delighted with the result.”
“A couple of days after [installing Extraglaze], Northumbria Water decided to drill right opposite our house but the elegant glazing really deadened the sound although we could hear it upstairs as one of the panes was off at the time.”
“We live in the centre of Shrewsbury in a listed building which has sash windows - and wooden shutters. The Extraglaze fitting was done without the need to adjust either the windows or the shutters. The units are both discrete and flexible, and can be moved readily to open the windows. The noise reduction is marked - probably 50-60% reduction - very noticeable living in the town centre. A very professional outfit with a first rate product - we are delighted with the results.”

Extreme Adhesive Test Video

We needed to use an adhesive not prone to the problems we'd seen in competing products.

We found one we preferred and tested it.

We had fun proving just how strong it really is. It's the same adhesive used to fix Extraglaze Secondary Glazing panels to window frames. The amount of adhesive used in this test is the same as we would put around the edges of a panel of size 1.2m wide by 1.2m tall.


Sound proofing your windows

Extraglaze secondary glazing offers many proven benefits:
  • sound proofing
  • thermal insulation
  • draught proofing
  • eliminates condensation.

Extraglaze, a company based in Shrewsbury, does all this without changing the appearance of your windows, whether inside or out.

It adds sound proofing to your window by creating a sealed cavity on the inside of your window. And you can still open your windows. Whereas an Extraglaze installation remains nearly invisible, other types of secondary glazing will change the look of your windows.

You must be very cautious if someone suggests modern replacement glazing is a good sound proofing solution. Is Extraglaze better? Quite simply, yes. In fact we have proven this to be the case, scientifically.

If your windows are old then they are probably draughty. Sound is exceptionally good at getting through channels, around rebates and between unsealed surfaces. Extraglaze seals up all those draughty openings, without making any alterations to the working of your windows.

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Read more about Extraglaze...

Read more about sound proofing...

Care and Maintenance of Extraglaze


Care of your Extraglaze Panels

With a little care and attention your Extraglaze panels will last many years to come. By following these simple guidelines they will continue to look their best, keep your home more comfortable every winter and prove their worth further even as they preserve your windows


Avoid fusion – Our standard foundation magnets are laminated (usually white) and not prone to this problem. If your installation includes the very dark brown unlaminated magnets then the magnet surfaces will benefit from being separated from time to time, to prevent them fusing together. We recommend you simply lift off and refit each panel at least once a year.


Avoid overheating – Extraglaze is not affected by the sun's rays to any significant extent. However, while the sun's rays pass through harmlessly, on the sunniest days the air in the cavity will get hot and this will in turn heat the panel, causing it to expand. In mid-summer this may be a problem for big panels, and especially those on South facing windows. Please act and apply common sense to reduce this risk. If you close curtains the windows, and therefore the panels, will get even warmer. We recommend you be aware of this, and do not hesitate to remove the panels during extended hot periods.


Refit correctly – If you remove a panel please make sure it goes back in the exact same location. If Extraglaze stickers have been applied then refit your panel so that this sticker is upright (this is a good reason to never remove the stickers). If in doubt, please check as follows: the butt joints on the panel (where the magnets meet in the corners at right angles) should meet identical butt joints on the window frame (no lengths of magnetic strip should straddle a butt joint). If the magnets seem to have stopped being magnetic this is because the panel is not lined up correctly with the magnets - please take a look close up!


Some cleaning rules – the panel material is likely to scratch if wiped or cleaned with anything other than clean pure cotton or a “micro fibre” cloth. Please always test any cloth in an inconspicuous corner. You can buy micro fibre cloths at any supermarket , or buy our own approved cloths and a formulated-for-purpose cleaner from the Extraglaze web site, or contact your fitter. Never use paper tissue on your Extraglaze. Paper products nearly always contain minerals, which give the paper surface some hardness. These minerals are extremely abrasive, although microscopic.


Condensation in the cavity – this can happen, especially if the panels are fitted on a cold day: while the panels are being installed the cold glass in your existing window will catch the installer's breath and this will be trapped in the cavity behind the Extraglaze. If this happens please simply take the panel off on a warm, dry day and waft the window so that the moist air is replaced! Condensation is also likely where windows are not maintained externally and insufficiently protected from the elements. The window frame should be inspected for dampness or water ingress (i.e. coming in from outside). Sometimes the cause is an overflowing gutter. If any of the wood that makes up the window frame is wet then this will sweat dampness into the cavity on a warm day, and this will condense on the outside glass when it cools again. Please also check the panel is always located correctly on the foundation magnets. For more information about condensation please see our article How to Stop Condensation.


Help & Guides

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How to stop condensation


A typical installation
For sash windows
For casement windows
Easy Open System