Thomas, thank you for responding to my post.
In quickly looking at Eric Hammond's pictures it looks like I can insulate on top of an existing slab. I started out assuming that all RMH was a long bench type design. After I get the plans for the garage off to the building inspector I'll have time to do my proper research on this site. Having said that how far away from an exterior wall is the burn chamber? Should I assume the same distances that one would use for a wood burning stove? I feel guilty asking questions that are probably answered on this site.
This site is going to be dangerous for me because I'm going...I want to do that..and that..and that... Is there going to be a seminar on building a RMH anytime soon someplace in the west that I can attend? I live 2 hours north of Seattle.
Thanks again for your help,
Leeanne