I'm planning the installation of my insert and I have a question about clearances. I have a concrete block chimney that is covered with furing strips and then wood paneling. Around the fireplace is marble glued to the block. I need to remove three inches of the paneling above the insert to meet my clearances. This means removing the marble on the top and the sides of the fireplace. I'm thinking it would be too expensive to buy new larger marble to replace the old. So I'm thinking about using a marble tile. Here's the problem. Currently the marble I have is the same thickness as the paneling and furing strips. The tile I'm looking at buying isn't that thick. What can I glue to the concrete block and then glue the new tile to that will allow me to make them flush.