More than likely you have what the industry calls a "Stress Crack". These occasionally happen after a window is installed and has a chance to cycle through the elements. It's usually related to the unit materials moving and adjusting itself to the climate changes. The window was more than likely built under normal conditions in the factory. When the glass is set in its adhesive it locks in place very firmly. Then the window is shipped over the road to it's destination and moved all over the place before it reaches it's final resting place. All this movement can put certain stress on the unit that almost puts it over the edge. Then you buy it and nail it to the wall by beating nails around it. Then you add the temperature changes that cause shifting, and snap goes the glass. It's a very common occurrence in the industry. The best thing you can do after a window is installed, is to use a low expansion type foam insulation around the inside. We use Great Stuff Low Expansion Foam for Doors & Windows that comes in the blue can. Don't use the red can under any circumstance around your doors and windows. Bad things can happen!!

The foam sets up and holds the window unit in place and keeps it from moving during the temperature changes. This will really cut down on any adjustments needed upon completion of the remodel. As for the glass, you can call Andersen directly @ 1-888-888-7020 and tell them you have a new window with a stress crack. They may send out a field rep or they may ask you for the unit number. So before you call them get out your eye glasses to read the tiny print on the tag located on the glass itself. In one of the corners you'll see the Andersen Logo etched in the glass. Inside that logo box is a serial number for that window. This number will reference their data base for everything they need to know about that window. So write it down and have it ready to go. Also to check the glass for any impact spots in the crack you just run the point of a pen down the crack. If something hit the glass it will stop in the hole along the crack. Good Luck!!!

Hi Guy - great answer Bud!

As Guy said, Sierrawine, contact Andersen right away and let them know what happened exactly as Guy suggested...

Thanks so much for the great information! I am always so impressed and amazed by all of you who share your skills and experience with us novices! We'll give Andersen's a call and see what happens!

If you don't have the model name for the unit, be sure to measure the glass you can see, width and height. The numbers around the logo only refer to the glass manufacturing date, which is what Andersen bases their warranty on. The glass is warrantied for 20 years, so it is covered by the warranty. Be sure they have a technician replace the glass. Since it's a new unit, insist they take care of the installation as well.