[Ferro List] Re; FC Drivel

[Peter Payne]

The bedrock tends to have trickles of water emerging from it and running 
down over the surface. I think I have to give this water somewhere to 
go; I am intending to place a 6-inch (at least) layer of drainage stone 
first. I already have outside concrete/FC  walls going down to bedrock 
around most of the perimeter as well as a central pillar; I am 
approaching this as a"room inside a room" structure. The actual living 
space will be built as a self-contained box, sitting on the insulated 
thermal mass, and the space between the inner box and the outer walls 
filled with insulation--probably foamEPScrete--with as little thermal 
bridging s possible. I like the idea of using an inner layer of denser 
foamed concrete, and an outer layer of almost all EPS, so the massier 
part is on the inside and the lighter on the outside, but I'm not quite 
certain how I'd do this. Perhaps  a temporary  plywood form to place the 
foamcrete. Finish the outside as you suggested with fiberglass/acrylic 
stucco (is that EIFS? Any particular product or component mix you 
recommend?)
All the best,
Peter

PS: just bought what should be a lifetime supply of e-lath: 1000 sheets 
at $7.50 a sheet. I still have a lot of #3 rebar as well as galvanized 
zigzag block bond, which I find great for sculpting.


Doug Lacy wrote:
> "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
>
>