Some foggy windows in double-glazed roof on hot days

Hennymore

With the weather getting warmer, we’ve noticed two of the six window units in our lean-to conservatory roof getting foggy on warm days.



It’s double glazing, so my first thought is that it’s something to do with the seal being broken. We’ve established it’s not on the indoors side. Access is a bit difficult so we haven’t been able to determine for sure if it’s on the outside or in between the panes.

Another factor is that two of the windows have some mystery cracks in the outside pane – we think they may be due to being fitted too snugly. But one of the windows with cracks is not foggy. The other one with cracks is foggy. And the second foggy window has no obvious cracks.

If it’s not a broken seal, I’m not sure why just two out of the six panes would fog up. It’s number 2 and 3 from the left, so it’s not even the furthest ones to a side.

Any ideas about what this could be due to, or suggestions for how to determine?

Hennymore

I!!!8217;m not able to edit from my phone, but a second stab at an image:

kazwookie

Broken seal, is my guess

Aylesbury_Duck

Yes, they look like they are "blown". Nothing you can do but get them replaced if you can't live with the occasional misting you see there at the moment.

Hennymore

Thank you both!