My husband and I just got an old Dutchwest Federal Airtight FA224CCL from a family friend. Our house has a chimney with no fireplace, just an 8" hole for a stove pipe. The floor in the room is laminate, and does not have a hearth yet, so we are looking to build one. I have found a couple of the old manuals circling the web, but I want to make sure we make the hearth properly. One manual says K=0.84 and the other says 1/4" non asbestos mineral board will suffice. We bought 1/2" wonder board and some slate tiles to put on top of it. Will this be a low enough K value? Is wonderboard mineral board? Should we track down micor? If we get micor, should we use both micor AND wonderboard? We do want to keep the hearth pad as thin as possible. Thanks in advance for the help, we just want to make sure we do this right.