Double glazed unit replacement
Double Glazed Units Replaced in Sound Frames
Misted or damaged glass does not always mean a new frame. We replace failed or cracked double glazed units where the existing frame is suitable, checking the glazing specification and the condition of the window before agreeing the work.
First check where the moisture is
Condensation on the inside surface can be wiped away and often relates to moisture in the room. Condensation on the outside is different again. Persistent misting trapped between the panes points towards a failure of the sealed unit, rather than a cleaning problem.
Notice whether the mark remains after both accessible surfaces are cleaned, and whether it changes with the weather. These observations help describe the fault, but do not try to prise the frame apart or drill the glass. A sealed unit needs safe handling and a replacement suited to the existing glazing arrangement.
What a sealed unit contains
A double glazed unit consists of two panes separated around the edge by a spacer and sealed together as one assembly. The gap and the glass specification contribute to its performance. When that edge seal fails, moisture can enter the gap and leave the internal faces misted or marked.
Replacing the unit means changing that glass assembly, not necessarily the outer frame or the opening sash. The distinction matters when the frame is still sound and the only problem is the glass. Adding new perimeter sealant to the window does not renew the internal seal between the panes.
Check the frame before keeping it
A unit replacement makes sense only if the surrounding window can hold and support the new glass properly. The frame, glazing beads, seals and drainage need assessment. A distorted sash or damaged frame may require additional work, even when the misting is the first thing you notice.
If a window also catches, leaks around the wall or has worn hinges, mention those faults. They are not automatically solved by new glass. The assessment should separate the glazing problem from any operating or installation issue, so the agreed repair has a clear purpose.
Specify the replacement rather than guessing
The glass assembly needs the correct width, height and overall thickness for the frame. The specification can also depend on where the window is located, including whether safety glazing is required. Measurements from the visible pane alone are not enough to order a replacement reliably.
Privacy glass, coatings and the appearance alongside neighbouring panes should be considered too. If only one unit is being changed in a group, discuss what is already fitted. The aim is a suitable replacement for that position, rather than simply a piece of glass that looks roughly the same size.
Cracked glass needs safe assessment
A crack can weaken the glazing assembly and should not be ignored because the frame still feels solid. Keep people clear of damaged glass and avoid operating an affected sash if movement could disturb it. The glass type and location guide the appropriate replacement.
It is worth considering why the crack developed as well as replacing the damaged unit. Impact, support or stress at the edges can require different attention. The frame and glazing support should be checked so the new unit is not put back into an arrangement that could damage it again.
A focused alternative to full window replacement
Where the frame is sound, sealed unit replacement keeps the existing window while dealing with the failed glass. Where both frame and glazing have substantial problems, compare a wider repair or replacement instead. We offer a free survey with a fixed written price and no-pressure quotations.
Describe the misting or crack in the form below, including which window is affected and any other faults you have noticed. The survey can then consider the glass, frame and supporting details together before the replacement unit is specified.
Questions
Common Questions
What are sealed units?
They are glass assemblies with panes separated by a spacer and sealed around the edge. A double glazed unit has two panes and is fitted into a supporting frame or sash. The whole assembly is replaced when its internal edge seal has failed.
Can you replace just the glass in a double glazed window?
Often, if the frame and sash are sound and suitable for the replacement unit. The dimensions, overall thickness, glass specification and supporting details need checking. A frame with other faults may need additional work.
Will new glass fix condensation inside the room?
Not necessarily. Surface condensation can relate to humidity, ventilation and temperature. Moisture trapped between the panes is a different fault. Identify which surface is affected before deciding that unit replacement is the answer.