What is a Broken Seal in Windows

WHAT IS DOUBLE-GLAZING?

Double-glazed doors and windows are made up of two sealed sheets of glass with an insulating void between them. This gap is either in the form of a vacuum, or more commonly, filled with a heavy inert gas such as argon. Together, the panes of glass and the void between them are very effective at preventing heat loss – in fact the U-value for a new double glazed window can be as low as 1.7, while a single glazed window in comparison has a u-value closer to 5.

However, overtime the effectiveness of the double-glazing can wane, especially if the seal goes around one of the panes of glass allowing air to replace either the vacuum or the inert gas between the panes.

The most common side effect of a seal going is that the window will fog up, as water vapour condenses on the inside surface of the window. So once you start describing your windows as foggy, misty or steamy when you try to look through them – it means that the seals have failed, or at least have started to fail.

WHY HAVE MY DOUBLE-GLAZING SEALS BECOME DAMAGED?

This can happen due to a number of reasons, however the most common tends to be general wear and tear as the double-glazing unit ages. Continuous changes in temperature cause fluctuations in the sizes of the glazed unit, since they expand in the warmth and contract in the cold, and over time this can loosen and damage the seals.

Particularly strong cleaning products can also sometimes eat away at the seal, so even though we all like being able to see through a really clean windows, make sure the cleaning product you are using is not chemically abrasive.

Other reasons for your double-glazing unit failing include faulty installations or faulty production methods, however on the whole these should be covered by your window installer, so it is key to make sure you keep your FENSA certificate and a receipt of any work carried out.

As the perimeter seal goes, then this moisture will start to enter the double-glazing unit. Normally there is a silica strip within the void, that absorbs small amounts of moisture and separates the glazing units, however, as soon as this becomes saturated the condensation rapidly increases leading to it misting up the entire unit.

It is possible to reseal your damaged double glazed windows and there are many sources on the Internet that will tell you how to do it yourself. However, to be honest we are pretty against this.

In the first instance, give your double-glazing installer a call. Most double-glazing companies will not attempt to reseal a window fitted by another company, however if you can get hold of the original installer, you may find that they charge a fraction of the price for resealing, compared with replacing the whole window unit.

The true fix though is sadly also the most expensive – simply replacing the window unit altogether. To be honest this is definitely not the most cost effective fix – replacing any form of double glazing (working or not) with a new double-glazing unit will obviously allow you to see through the window and it will have some impact on energy efficiency, however the energy savings you will make will go no where near to covering the installation costs.

However if the view out of your window is your pride of joy, unfortunately you only have one choice and that is to pay for a replacement. We really do recommend getting hold of the original installer if you can though, since they might be able to re-seal it or offer you a repeat-order discount.

WHAT ABOUT WARRANTIES?

Whatever you do, check to see if you have a warranty/guarantee left of the windows. If you do and the windows are still showing signs of inner pane condensation, then presume that the cause was faulty installation and you may be able to replace them free of charge using the same company. However, if the warranty has expired then expect wear and tear to be the main contributor, and brace yourself for the replacement of double glazed units.