There are a few reasons why a double-glazed unit may break down and mist up,  including how the sealed unit was made, how the framework was made, and/or how the double-glazed unit was fitted into the framework.

We have removed units where the frame has not been drained for water escape and the unit has been sat in a ‘puddle’. We will drain every window where necessary before installing the new unit, on a minimum of a 5mm plastic glazing packer.

Most units replaced by us are south or west facing where the sun is at its strongest during the day. This alone is the major contributor to premature sealed unit failure combined with the winter freeze and thaw, which all puts extra pressure on that seal between the panes.

Richard’s Frame Fitting Techniques

There are a number of different glazing techniques for fitting double-glazing sealed units into different frame materials such as wood  as opposed to either PVCu or aluminium frames.

There are some important do’s and dont’s to ensure a reasonable life expectancy for the sealed unit.