Heaterman, a few years ago, my cousin did the same thing. Used some kind of black roll material, it had 2 layers of bubble and maybe a thin layer of foam. My cousin can't keep enough wood. He abandoned a gasifier for a CB. Now we are looking for other options. I love my radiant heat in my house. I still feel bad for those who messed up, because now it can't be fixed. It would be fun to talk to the John Deere owner in a year or 2, see how they are doing.