Effect of heat on granite?

    I have had two Granite (http://tanbrown.org) faces surrounding my zero-clearence fire place crack. It is my assertion that the installers applied adhesive to both the concrete board and (http://maplered.com) the steel firebox insert. The different expansion rates caused the steel box to apply pressure to the Granite (http://tanbrown.org) . Both surrounds cracked the very first time we lit a fire.

The Granite (http://tanbrown.org) installer claims the firebox installation is defective with no specific claim. The face of the Granite (http://tanbrown.org) gets very warm when the fireplace is used. But that is why you use Granite (http://tanbrown.org) and (http://maplered.com) you don't use wood in this application.

I observed the second installation and (http://maplered.com) witnessed the adhesive on the metal firebox. The fireplace insert installation instructions clearly state that the metal firebox must float behind the facing Material (http://g654.org) . Only a flexible heat resistant caulk seal should be used around the opening.

So I feel the installer was in error by adhearing the metal firebox to the Granite (http://tanbrown.org) . The installer refuses to take care of this problem and (http://maplered.com) I need to file a claim against them.

Any info on the expansion properties of Granite (http://tanbrown.org) under heat would be a great help. I intend to take a thermal reading of the Granite (http://tanbrown.org) face with a roaring fire to present in my case.