Exploding Car Window

My friend, Andrew, was in Breckenridge, CO last weekend skiing. Friday night he parked his Subaru in an open air parking lot adjacent to his lodgings. The following morning he after depositing his boots and bag in the back of the Subaru, he closed the rear hatchback door and the front passenger car window exploded! Thankfuly no one was hurt during the incident, but we are quite curious has to why this happened?

Some background information to assist in your mulling over…
A. It’s a 2010 Subaru Outback.
B. There were no visible cracks or dings on said window. However, this same window was replaced when someone broke into the vehicle in the summer of 2011, so it’s an after market window. The repairs were not completed by a Subaru dealership, but by a nationally recognized auto glass company.
C. The vehicle is garaged when he is home, which is downtown Denver, CO.
D. The overnight low in Breckenridge was 10 degrees and the high during the day was 20 degrees.

I have my own theory about this occurance and everyone I mention this to says I’m nutts and they have never heard of such a thing happening. Any enlightenment would be greatly appreciated and recommendations to avoid this from happening again. Thanks!

There may have been a small crack out of view, like under a cowl at the bottom of the window. When it reached a critical length, there was a catastrophic failure. Temperature cycling alone won’t make a window fail. There has to be a crack somewhere, and temperature cycling slowly enlarges the crack. I had this happen with a safety glass shower door. I was in another part of the house when I heard it explode. There were little pebbles of glass everywhere.

My suspicion is that either there was a very small defect in the glass, or it wasn’t installed in the mechanism “just so”, meaning that it may have been slightly out of alignment and had more stress on it at one corner or side. Finally the low temps and the air pressure from shutting the back hatch was enough to make it blow.

BTW, auto glass is supposed to shatter into a million pieces, it’s safer that way.

Side window glass is made with “internal pressure”, it is called tempered glass, which means when the glass breaks it explodes as you describe and shatters into a zillion little roundish pieces. Surprisingly these glass bits don’t have sharp edges and rarely cause cuts to people. It is just a big ugly mess to clean up.

Extreme cold temps can cause the glass to shatter. I had this happen on a car overnight on a night when the temp was about 5 degrees. Likely there was a manufacturing defect in the glass, or a scratch, or small chip in the glass surface that contributed to the event - but the cold was likely the largest reason behind the window blowing out.

&*$# happens.  There are several possible reasons, but there is little you can do one way or the other.  I have found that most insurance policies cover glass.  They likely will come out, replace the glass at your home and the insurance likely will cover the whole cost.

I agree with asemaster. A small flaw combined with cold temperatures combined with the jolt of shutting the hatch could easily do this.

Thank you all for your kind consideration. You have re-inforced our concerns. With that said, the auto glass company replaced the window, at no charge! Even though the warranty had expired 6 months ago. Thank you and merry christmas!

the auto glass company replaced the window, at no charge! Even though the warranty had expired 6 months ago.

These are the things that are too often forgotten.   Keep the glass company in mind and if a friend or neighbor needs glass work be sure to tell them about that glass company.
"...the auto glass company replaced the window, at no charge! Even though the warranty had expired 6 months ago."
Why not name them and give them credit? What did they say about the cause? Undo stress and tiny flaw? I am amazed at the environmental extremes which auto glass successfully endures. Thank you.

Do they make sandwich glass for sidewindows anymore,?our old pickups used to have this,just curious-Kevin