[Ferro List] Re; FC Drivel

[Doug Lacy]

"A concern 
is thermal break from the rock--as rock conducts pretty well, and there 
is exposed rock at several places around the site, I think the rock will 
get pretty cold in the winter. So broad footings incorporating 
insulation may be necessary. Maybe a section of relatively high-density 
cellullar. As the land is very sloped (approx 4.5/1), the floors of the 
rooms will be terraced; I am thinking that the wedge-shaped space left 
between the floor and the bedrock could be filled with thermal storage 
mass; this of course would need to be insulated from the rock itself.
Peter"

I don't think you have to go very wide to put a heavy wall on 2 inch blue EPS dow board.  It is 25 psi.  To make a solid connect to the bedrock, I would grout in short pieces so you have a good load transfer.  I like the idea of using the wedge shaped area as a heat sink.  Maybe you can put down some one inch EPS dow board on the slope, and then fill over with some super low density cellular so it will level up perfect.  The low density will function well as a different kind of heat sink, radiating more slowly, while boosting the thermal block provided by the blue foam.  As you approach your finished floor heights for your terraced interior, maybe pour a cheap mix with some heavy stuff in it for a larger heat storage capacity near your thin radiant slab.  

Sheathing the entire exterior with EPS for insulation is possible and it will give you the needed cold climate insulation while helping the structure store inside energy.  You may have to do small pieces.
Doug
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