[Ferro List] 3 questions for Walter

[Walter Jeffries]

On Feb 26, 2008, at 5:38 PM, Keith B wrote:
> Hi Walter, Any more details on what you are planning for your  
> "insulating concrete layer"?

We've done a fair bit of the light weight concrete already so we've  
had a chance to work the mix out. There have been the test structures  
as well as usage around the chimney and wood stove. Basically we are  
going with a vermiculite light weight concrete. See these posts:

http://www.google.com/search?&q=site%3Asugarmtnfarm.com+vermiculite

To get R-value the insulating layer on the roof will be fairly thick.  
But we don't really need as much R-value as with conventional wood  
frame construction. I say this because the house is staying warm even  
with very minimal heating from a very small wood stove. I suspect  
that this is because of the thermal mass effect. See the numbers here:

http://sugarmtnfarm.com/blog/2008/02/will-cut-firewood-for-heat.html

Above that is the hard shell of another relatively thin PVA concrete  
layer. That is very non-porous. See the dog house post I mentioned  
before. Before I do it I plan to understand flyash, currently  
testing, and possibly use that in the top coat.

Above that will be a thin layer of conventional closed cell foam  
insulation, poly plastic sheeting, insulation, etc and then sand much  
like the PAHS type construction.

The top layer will eventually be soil and plants.

All the layers provide water proofing. Currently the house is almost  
water proof with just the first FC layers. There is just a little  
wicking in a couple of spots where I put an experimental piece of  
rebar in the roof and it created cracking. I should have put the  
rebar under the lathe, not over. Live and learn.

There is no condensation on the inside of the roof even though the  
roof is not yet insulated. So far it has been through two winters  
(last and this) as well as spring and fall which are quite wet here -  
lots of rain storms.

Cheers,

Walter Jeffries
Sugar Mountain Farm LLC
Orange, Vermont
Pastured Pigs & Sheep
http://SugarMtnFarm.com/blog
http://HollyGraphicArt.com
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