Why double glazing fails
Causes of misted double glazing
Why double glazing fails. Whether a window is made from aluminium or plastic or timber it is quite likely that over time the glass will fail. Whilst more modern aluminium or plastic frames might require minimal maintenance the older timber framed double glazing is more vulnerable to failure.
Your double glazed “units” are hermetically sealed units containing either simple air or an energy efficient gas called argon, with thermally efficient coatings on the inner panes of glass. If your windows are steaming up or condensating internally, the simple explanation is that the hermetic seal of the double glazed unit has broken down. What cause the seal to break? What you may not know is that all things including windows expand and contract with heat and cold, this expansion and contraction may over time cause the hermetic seal to break.
When the seal is broken, moisture is now entering the double glazed unit causing the condensation you see internally subject to whatever weather conditions are prevalent at the time or the internal moisture, especially in bedrooms.
Other common causes of failed double glazing can be blocked drainage holes in the frames and incorrect installation of the unit. When the unit is fitted it site on a glazing packer, if this packer isnt correctly situated across both leafs of the double glazing, one leaf will move over time breaking the units seal.
You do not need to replace your entire window, It is just the double glazing that needs replacing. On much older window systems that are now discontinued there is a risk that the rubber gaskets may have become brittle over time and snap on pvc windows – Replacing these gaskets is recommended when replacing your double glazing as they keep the unit tight in the frame preventing any drafts through the window.