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insulation sound proofing draught proofing stop condensation
ExtraGlaze contact details
Instant quote
Extraglaze Explained
Measuring Guidelines
Solutions for listed buildings
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  • 2 weeks ago
    ratings 5
    Brilliant solution for beautiful, but cold, sash windows.
    Excellent, from the time they sent the sample product and the informative booklet. Ordering was simple and when I queried the delivery date they responded with a personal phone call.
    The secondary glazing arrived as ordered, fits perfectly and we are now so much warmer in our...
    Mrs Carole Proud
  • 1 month 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.
  • 4 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
  • 5 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
  • 5 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!

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?

Extraglaze can be an excellent long term solution, reducing and more often than not eliminating condensation. For a day or so after fitting it is common to still experience a little condensation on the original window, because the fitter breathes all over the window while working, and his/her breath is caught in the gap as soon as the panel is applied. However on a dry day the panel can be removed, for dry fresh air to replace the damp air. Condensation does not usually return (unless there is a fresh source of dampness within the window itself e.g. leaks or damp wood or bricks). Instances of mould are reduced dramatically, usually eliminated, as the cavity stays dry. Consequently the life of the paintwork on an intricate window frame is greatly extended, and stays looking fresh.

You may read that secondary glazing does not solve condensation. This is commonly known for secondary glazing made of glass. Extraglaze however is superior to other types of secondary glazing because the acrylic can maintain a comparatively warm surface. A chill does not pass through the acrylic nearly as well as it can through glass (glass will transmit heat about 5 times faster. Please note there are some incorrect statements on the internet that suggest it is the other way around!). So the inner pane of your window, i.e. the Extraglaze, is not prone to collect condensation.


IMPORTANT NOTE: Condensation is a symptom of insufficient ventilation i.e. a humid indoor atmosphere. Extraglaze does not cure this. Humidity is commonly a result of steam from showers & baths, kettles, poorly vented tumble dryers, cooking pots and a busy house full of people. Condensation may settle elsewhere i.e. humidity may condense on another cold spot in your building. Condensation is most common upstairs, because humidity rises up with hot air. If you still experience condensation after Extraglaze has been fitted then do check it for gaps i.e. where the magnets may not be mating correctly. This suggests incorrect fitting. If there are no obvious gaps then this is a warning sign that you have an abnormally humid room (therefore poorly ventilated or entirely unventilated) and action is required to reduce this. Such poor ventilation is very likely harmful to your health and the fabric of your building.


What depth of air gap is best on my windows?

For thermal efficiency a 75mm air gap (or cavity) is ideal, but on many windows this is not practical (and unheard of on domestic double glazed windows). In practice any gap over 25mm is still a good one. Less than 25mm and more than 100mm is not nearly so effective. Deep air gaps can still be very satisfying (far better than no gap at all), but the large cavity allows air to circulate and so heat is transferred from outside to inside. For sound insulation a gap of 30mm is moderately effective (to the human ear at least!), increasing in effectiveness as the gap gets larger. In our tests at the Building Research Establishment the test equipment suggests an optimum at 125mm, and on larger gaps the additional benefit, while helpful, is minimal. However please do note that larger gaps compromise thermal efficiency.




How do I keep Extraglaze clean?

Extraglaze must only be cleaned with an new/uncontaminated microfibre cloth. Please never use any other type of cloth, and never use a paper tissue (tissues usually contain tiny amounts of a mineral powder which will scratch just about anything!). Microfibre cloths are very cheap and very easy to find in any supermarket or hardware store. A very clean soft cotton cloth might sometimes be acceptable, but is nowhere near as effective as a microfibre cloth. Whereas a microfibre cloth will literally grasp dust particles as soon as it comes in contact, a cotton cloth will just sweep some of the dust around.


What cleaning agents shall I use on Extraglaze?

Extraglaze panels are best cleaned with VuPlex® anti-static cleaning fluid (this was specially developed for the aviation industry, for cleaning cockpit windows). A tiny amount will clean and polish an Extraglaze panel in a few seconds with minimal effort (always using only a microfibre cloth). You can buy VuPlex® in our online shop. If you employ our "Fitted by Us" service then we will supply you a can of this at the end of the project. You can also use very dilute solution of soapy warm water, though without both the anti-static and the polishing effects.




Is acrylic better than glass?

Acrylic is better than glass in many ways. It is safer, as it can take a hit unlike glass (acrylic will certainly never be as dangerous as broken glass). It is also much lighter, at least half the weight of glass (plus Extraglaze has only magnets rather than a frame). For these two reasons Extraglaze is safe and easy to lift away to open or to clean your windows. For secondary glazing purposes acrylic is also flexible enough to take on the shapes of old timber window frames, and numerous layers of paint, which are often far from perfectly flat. Trying to attach a glass panel using magnets in the same way will almost certainly fail, and indeed be very dangerous!


Why do you use acrylic for Extraglaze panels?

Acrylic is an excellent choice for Extraglaze panels. Acrylic has been used in lots of glazing applications for many years, including safety guards, motor cycle helmet visors, car headlamps, police vehicle protection, greenhouses and even aircraft cockpit hoods. It is tough, does not warm up and expand like other plastics in the sunshine, is unaffected by UV rays, does not discolour and is optically very clear indeed.


Are the acrylic Extraglaze panels brittle?

No. Acrylic is known as an "engineering polymer" which means it is a premium material of choice for important components in all kinds of tough environments. We have first hand experience of dropping quite large panels (by accident of course!) - we worry more about the damage the panel might do than the damage to the panel itself!




What colour are the magnets?

The magnets supplied by Extraglaze have a coloured top surface i.e. all the major surfaces you see when the panels are removed. Several colours are available when you place your order. Why not request a free sample? The obtuse edges (on the thickness) however (about 1.5mm) are dark brown, which is rarely of consequence, and are often unseen. The selected colour will be applied at the factory.

PLEASE NOTE: Alternatively, if you want the magnets painted (and indeed the panels) please discuss your requirements with us. For the panel edges we can certainly make this much easier for you to do, or we can do the painting for you. For more than a few panels we recommend we do the painting for you at the factory (this is an extra chargeable service).

What are “foundation magnets” ?

The “foundation magnets” are those that remain on the frame even after the panels are taken away. Please note that the panels also have magnets, permanently on the panel around the perimeter.


Can I paint the “foundation magnets” ?

Yes, but please always discuss this with us first, because we will make your panels differently. Of course, before you apply paint, the magnets should be rubbed clean with a fresh cotton cloth, then painted with a primer, undercoat and top coat just like you paint the window frames themselves.



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Help & Guides

measuring icon


How to stop condensation


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