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Extraglaze Explained
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  • 5 days ago
    ratings 5
    Great product, great service.
    It took us a while to decide to invest in secondary glazing from Extraglaze but we are glad we did!
    From the measuring and fitting instructions to checking details and requirements for accessories and arranging delivery to suit, the service was first class.
    Product : We tried...
    Thank you so much for your praise. We enjoy what we do here - and all the more when we read such great reviews like your own. We hope many others are encouraged to try Extraglaze as a result.
  • 3 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
  • 4 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

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.


Does Extraglaze Stop Condensation?


Does Extraglaze stop condensation?


Yes, we know it does because...

  1. we have had it tested scientifically at Coventry University - simply ask if you wish to read the report
  2. our customers tell us it does (see first hand testimonials in our Reviews pages)


Did you know, for example, that the acrylic glazing we use has one fifth the rate of heat transfer when compared to glass. This means that Extraglaze tends to stay much closer to room temperature. Whereas had we used glass it would stay cold, and be prone to condensation. In short, a "glass-in-aluminium-frame" type of secondary glazing is not a solution if you wish to tackle condensation. But Extraglaze is.


But... lots of things can be at work to cause your condensation problem, and sometimes these are too many and too severe for Extraglaze to solve all by itself.


Of course, please note, while Extraglaze can stop water condensing on the inside of your windows, it does not stop condensation on other surfaces in your home! When condensation is rife, or persistent then we recommend urgent action, most of it very simple and practical - please read our other article How to Stop Condensation.


Did you know...?

- Condensation usually appears worse on upstairs windows, because:

    • heat (and steam) rises
    • the rooms upstairs are probably not heated like the living spaces are downstairs
    • that's where the occupants spend most of their time (sleeping!), and add dampness to the air, as they breathe.

For this reason, when condensation is a problem, we always recommend you insulate the upstairs windows as a priority.


- Condensation always finds a cold spot to land on. If you use Extraglaze to insulate some windows, but don't insulate the others, then condensation will gravitate to the uninsulated ones.


- Extraglaze can often stop condensation caused by the inside air, but it cannot stop dampness and water leaks coming in (into the cavity) from outside.


- Radiators should, whenever possible be located beneath a window, not against an internal wall. This is because the air circulating around a window will keep it dry, and also it dramatically reduces "chilled feet" syndrome.


- If you have a warm room, but still have cold feet then you have "chilled feet" syndrome,  consequence of having radiators installed in the wrong places. It is normal to turn up the thermostat to compensate. However, this will add considerably to your fuel bill, so beware! In the long run, not only can it work out cheaper to have a plumber relocate your radiator/s, but you will feel so much warmer if you solve this problem, and enjoy warm feet!


Water or damp air in the cavity?

It is quite common for condensation to appear in the cavity very soon after Extraglaze is installed. There are two reasons for this:

- the installation took place on a cold or damp day. A fitter will work so close to the window that his or her breath will condense on the external glazing, or simply "fill the air" that is trapped when the panel goes on. On very cold days there is nothing the fitter can do - it will get wet again just as fast as a cloth can dry it!
- the materials in the window frame might well be damp (from the condensation it suffered prior to fitting your Extraglaze). Now the following is good news: the secondary glazing has made a gap between the new and old glazing, and the cavity has started to work like a greenhouse, warmed by daylight. During the day any dampness starts to sweat out of the frame. This "sweating" effect is normal, and good for your window, because the window frame is drying itself out. Consequently the warmed air in the cavity will contain an increasing amount of moisture - and this will explain any ongoing condensation noticed inside the window. So, at night, or during a cold spell, this moisture will condense onto the glazing. Later in the day you may notice it has evaporated, but it is still within the cavity. You may see this same condensation appear again and again until you remove the moist air.

Happily both of the above are temporary, but do need a little effort to resolve. The solution is to remove the panel on a dry day, when the room is well ventilated and give the glass a wipe. Next, a simple waft of dry air into the cavity is all that is needed. A wrong day to do this would be while you are drying washing indoors, even using a tumble dryer, or there are other reasons for the room to already contain damp air.


In more severe cases you might have water seeping into the window frames from outdoors, in which case you need to deal with the cause. The common causes are:

  • a gutter is clogged, and water is dripping or running over, or splashing somewhere near the window
  • the paint is not in good enough condition to protect it from the weather
  • there are gaps in the frame, allowing water or damp air in


Good maintenance will save you money and your windows

When you find water in the cavity then it is essential to take the above action to stop the problem. If you do not then your window could become badly damaged, by rot, black mould, or swelling. The natural cycle of wetting and drying causes, in turn, swelling and shrinking. These eventually weaken and breaks the joints. Furthermore swelling will cause you to fight to get the windows open, which will be harmful. The window must be allowed to dry out and then must promptly be painted to a professional standard. Otherwise the window will soon be in need of a costly repair.


How to Stop Condensation

Help & Guides

measuring icon


How to stop condensation


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