I need help on a masonry issue. I want to put a stone veneer on my fireplace. The fireplace is 12’+ in height so I removed the brick that was on it to insure the added weight of the stone veneer wouldn’t overload the fireplace’s footing. After removing the brick I have found that the metal firebox liner is flush with the face of the remaining masonry that I was going to adhere the stone veneer to. My first thought was to put a metal lathe across the firebox but don’t I need some space between the firebox and the veneer so the mortar doesn’t crack due to the heat? Also, the old brick and the lintel that I removed, spanned the opening of the fireplace and was alot lower than the height of the firebox opening.What can I put across the fireplace to lower the opening and can also hold the veneer?