Failed double glazing can be painful

The failure of a double glazed door or window is rarely serious, Misty windows will not generally cause a house to collapse, but they can be a constant frustration for home owners.

The condensation which occurs between the two panes of glass of the double glazing unit will significantly reduce visibility through the window or door, and is effectively impossible to clean or repair without replacement. The windows and patio doors at the rear of this Sheffield property all displayed signs of staining and condensation within the glass, with the right patio door being particularly affected.

Moisture levels in this property exacerbated the problem, increasing the visibility of this defect. Where failure has occurred, however, the double glazed unit will cease to function effectively as insulation. This will result in excess heat loss, and higher utility bills for the owner. Irrespective of the visual problems, this lack of insulation can quickly make replacement of the double glazing a more cost-effective option that it may first appear.

Double glazing, or insulated glazing, is generally manufactured and installed as a sealed unit. The sealed space between the two panes of glass is filled with a gas which reduces the heat energy conducted through the unit. When the seal is broken, water and air can enter the space; these transmit more heat through the unit, and quickly reduce its efficiency. There are a number of variations of insulated glazing, including triple glazing, and units sealed with a foam spacer separating the panes rather than metal. Double glazed windows and doors also provide acoustic insulation, which is useful for properties located near busy roads or beneath a flight path.

Repair and replacement of individual affected windows may be possible, rather than installing new units.