Doors and Windows - Cracked double pane window

We have a 3-foot diameter, semi-circle, double pain window that has suddenly developed a 10 inch crack from the base to about halfway up the middle of the window for no apparent reason. I have a couple of questions for your consideration. First, can anyone venture a quess as to why this crack happened? When we first discovered it, I figured a bird had hit it, but the crack is only on the inside pane, not the outside. Could it possibly be a contraction/expansion temperature thing? We live in San Diego where the temp differences aren't that great. Could it have been a sudden strong wind? Again, why would it be cracked on the inside then? No kids, so horseplay is out of the question. Secondly, do you think the crack has comprimised the windows integrity? I think we can live with it if it doesn't get any bigger or the rest of the window won't suddenly shatter. Lastly, any estimates on what we might expect to pay to have the window replaced? It looks like it's got a metal frame. Thanks for any and all thoughts.......
fishkat

Hi
If it crack that means there was some shifting involve.
As for the window it will fog up due to seal breakage.
you will have streaks in it and condensation.
You will need replacement.

cheers

pg

Since the INSIDE pane cracked, it ain't birds or wind. It's settling. You are looking at replacing the IG unit. Not a big thing. Arched top -- that WILL increase the price, but still not bad. The arches are pretty much a standard thing.

Call a glass shop and let THEM come measure for the new IG unit. It'll take a week or two to get, and they can install it in about an hour.

Fishkat,

There a couple of specific technical issues that can cause the internal lite of a dual pane IGU to crack as you described (besides the reasons mentioned, which are also real possibilities).
Depending on the age and manufacturer of your windows, that particular problem may be covered by warranty. I would suggest you check with the manufacturer and find out if you are covered.
As both Lefty and pgtek mentioned, you will need to repace the IGU (fairly simple process), but if the unit is under warranty.....