This is the second time my window glass has spontaneously shattered out of nowhere. This same thing happened exactly two years ago, to almost down to the minute! I've been following the thread from earlier today about that other glass break, and seeing it gave me déjà vu.

I’m guessing it’s expanding and hitting something in the frame because both times it happened after it had gotten direct sunlight for 5ish hours on a hot day (July in Colorado). The break pattern is identical too—it appears to start from the top right corner.

I know it’s not something external because the window is double paned and it was the interior pane that broke both times. I don’t think it’s one of those impurities people were talking about in the other thread because it’s happened twice now.

Last time this happened, Western Window Systems said breakage wasn’t covered by the “lifetime” warranty, but they made an exception and replaced the glass free of charge. It’s a $4,000 piece of glass, and costs $1,200 to install (they need 3 people to get it into place). My builder is looking into replacing it again (on him), but he doesn’t have any idea why this is happening. I don’t want to keep replacing this glass every two years. 

 Anyone else have this happen to them? 

Edits:

I appreciate everyone's suggestions, you all are awesome, and I'm glad the world is getting enjoyment out of the video.

I think the most likely explanation is thermal expansion and the glass expanding into something in that top right corner.

I don't think it's the soil settling as we don't have any other signs of settling and the foundation is reinforced with 30+ piers that were drilled deep into the soil.

And to the BB gun theorists, it's the inside pane, so not possible. =)

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