After more homework and thanks to some proper guidance I chose to go with the heritage. . Now I need to make my hearthpad. I have my half inch micore 300 to meet the required r-value and I am starting on the 3/4 inch plywood subfloor. I have read here the proper sequence is : 1. micore 2. cement board 3. thinset and 4. tile. My question is all the cement board manufactures suggest to use thinset both above and below the cement board. Now, my better judgement tells me that thinset and micore don't mix. Does anyone have experience with this scenario? What did you use Rhonemas? Should I place a layer of sheet metal and metal lathe between the micore 300 and the cement board? Should I just set the cement board down on the micore then thinset then tile and hope when I put my 500 lbs stove on top, I don't get cracks at the seams of the cement board By the way the size of the pad is 60 wide by 42 deep. cement board comes in 3' x 5' sheets therefore I need to use two pieces and make a seam. I considered laying "1/4" cement board after the micore then thinset, then stager another 1/2" cement board, more thinset then tile. Does anyone know how they construct the UL listed hearthpads?? Thanks!