Ok it seems like everything is pointing to my garage slab. So a pour over it is, lots of work and money, but I am figuring a wood savings of 8 to 10 cord per year based on past usage.(2014/15)
So will zip ties be enough to hold tubing in place, I used staples last time.
Best kind of tubing.
I will keep runs 250 or under.
Add more insulation to outside concrete walls, bringing them to R35.
Vapor barrier on top of current Crete?
2" foam board?