looking of input for RHM in home

I was going to put a wood stove in the corner of our living room until I found this site and learned about the RMH. My question is we just put in Wood flooring in and I do not want to built it using materials that will stick to the floor but is still efficient. I was thinking of a wood box to put the tubing and stuff in but am wondering what to use inside as a thermal packing that will retain the heat. Should I use a Cob mix inside the box or is there other material i can use?

Thanks.