I have looked through the manual several times and even did a search for R-value, k-value and just the word value, all to no avail. The manual simply states that I need a 24" hearth in front of the heater. My existing hearth is only 16" so I know that I need to extend it to the min. 24" from the door however, I would like to know what type R value I need before I start designing the hearth extension. If anyone knows this information or where I can get it please let me know. Oh and by the way calling the manufacturer is did me about as good as calling the dealer "uh...um...I don't know why it doesn't state the r value, hmm, I would say just put some 3/8" duroc down you should be fine"
