Hello all, I'm having a QuadraFire SantaFe pellet stove installed and need to construct a hearth pad. Off the shelf pads so far don't meet our design needs within budget so I figured I'd save a bit and build my own. The specs from QuadraFire require a hearth that extends 2 inchs from the rear and sides and 6 inches from the front of the stove. At 26in wide by 22in deep (rounded up) I'm planning a 30x30in pad. The specs also require a pad that provides minimum 1/2 inch thickness minimum R Value of 1.0 minimum K Value of .49 Materials I plan to use are 1/2in micore board at 1.1 R 1/2in HardiBacker or Durock Cement Board at .26 R topped with thinset mortar and slate tiles (not sure what the R value is there) The Micore and Cement board have a 1.36 R Value which is a little over what is called for and I assume the slate will add slightly to that. I searched for the k values and found a formula K = 1/r which gives me .73 for K. Is higher or lower K better, and does this meet the requirements for this pad. The pad will be placed on top of a 3/4in hardwood floor with 3/4 plywood subfloor. Am I planning this out correctly? Thanks for your input.