Cob Re: Carpet/cement per Pat

[Patrick Newberry]

You mentioned Earth - not so good sandwiched between the layers of 
cement/carpet, 
Yet latter on you mention the wonderful aspects of a living roof (I 
too have a high opinion of)
But then why is a living roof good and earth between two layers not 
good?  I have thought of putting  living roof on top of this but at 
this point I'm still leaning toward the sandwich roof. 

Also on the shed style roof, it will probably not be "flat" like a 
sheet of plywood. Last time I used this method, the carpet dipped 
between by 2x4 supports due to the cement carpet drooping between 
supports. My brain told me (but it's been wrong before) that  hey 
this is better because it's more like the corregated roof (right 
word?) anyway I did't fight the wavy-ness by pulling real tight 
between the support. 

I'll will go ahead and start making some "test" sandwiches. 
One test we did ealier here was using peanut shells and a small 
amount of cement. Being in Geogia (not too far from Jimmy's place) I 
have access to as many peanut shells as I want for free. We mixed 
them with cement and made inch and a half thick squares. I stood 
gently on it (about 150 lbs) and it  held. My son stood on it and it 
broke (about 250 lbs) I have thought this might be an interesting 
middle layer for the roof as the weight of  the squares as much less 
than  a cement square would be. 


Pat
Mauk GA



> 
> Earth - not so good.  Earth is wonderful stuff and super in cob, rammed
> earth, stucco, floors, thermal storage, growing stuff on your roof,
> buffering short-term temerature fluctuations, etc., but as insulation,
> it's heavy and only about R-.2 per inch (dry), eg.: a foot of earth is
> less insulating than 1" of straw (~R-3).  Weight of a cubic foot of dry
> earth ~ 120# dry - Weight of a square foot of compressed straw 1" deep " ~
> 8 ounces!  heavy = more structure = more effort and or expense!
> 

> 
> PS:  Are you receptive to the idea of a "living Roof" surface on top? 
> That's one of the techniques of which I'm particularly fond and one I've
> been experimenting with since the 60s.  It's ecofriendly, cheap, gives an
> almost eternal life to the waterproofing membrane underneath (no UV, no
> freeze and thaw cycle, no dry and wet yoyo, no physical trama from foot
> traffic or falling branches), manages run-off better and it's "purty".
> 
> 
>