Hi everyone, i just put in a Royal Hearth 42" wood burning fireplace in my house. (It sits on concrete, its a slab house). I need to build a hearth extension for this particular fireplace, (i've never built a hearth). From what i can tell from reading the instruction manual i need a R value of 1.03, and im trying to figure out what would be best to use for the framing of the hearth itself, and what to use for the R value (ive heard Micore 300) and then tile over that but im not 100%. Im trying to make a raised hearth to go up to bottom of fireplace opening. Its got to be 30"infront of fireplace minimum, and 12Inches on either side of that. Does anyone have any suggestions or (how-tos) . Any info would be greatly appreciated.