Condensation problems in double glazing

12 November 2012

The sight of condensation within a double glazed window unit is usually a sign that there is an issue with the sealed unit of the windows. Put simply, the edge seal of the window unit has failed in some way and as a result, is allowing moisture to enter the window unit in the form of condensation. Typically the sight of moisture / condensation within the unit means that the sealant (silica) between the glass and the frame will have to be replaced or renewed. Over time, the silica may harden with age and as a result, may not perform as well as it could do at absorbing moisture.

What is the main cause of condensation in double glazing?

For condensation to form in a double glazed window the surface temperature of the window needs to be cooler than the air inside the room.If the sealant of the window unit has failed the warm air will enter the gap between the glazing. When the warm air makes contact with the cooler air it condenses. The same process happens also with single pane windows and produces the all to familiar problem of condensation.

Condensation on double glazing


What problems are caused by condensation in double glazing?

If the condensation problem is left untreated the condensation can travel down the glass and on to the wall below causing potential water damage. This can in turn lead to the possibility of problems with black mould or in more serious cases decay in the form of dry rot or wet rot. The other noticeable problem is “fogging” of the window unit which is unsightly.

Preventing condensation occurring in double glazing

The best way to stop condensation forming is to take preventative action by checking the seals of the window unit for signs of breakages or hardness. This can be done simply by running a finger around the seal. If any defects are found within the seal then it is worthwhile considering replacing the seal or seeking further advice from a glazing professional. It is also advisable to check moisture levels within the property as high moisture levels can make condensation problems worse. High moisture levels can be controlled through correct ventilation of the property or through mechanical methods such as dehumidifiers.

Further advice of controlling condensation

The condensation control pages on this website are full of tips and advice on controlling condensation within the property. For further advice or to arrange a condensation survey call your local team on 0800 288 8660 or complete the online condensation survey request form.