Cob Curious

[Grace Benjamin]

Hello everyone;

I've been on this list for a while, but rarely posted; well now I have 
something to ask about...  I'm drawing up some plans for a cob/strawbale 
house.  Two story, in southern New England (eastern Conn. to be 
specific.)  I'm aiming to cut costs, recycle as much as possible, build 
sustainably, and drastically minimize my electrical usage- or at least 
convert as much to solar power as possible.  I have some questions, some 
on foundations, and some on design.

First; foundations.  I don't think I want a basement, while I have a 
nostalgia for basements (the house I grew up in had one, and so on..) 
I'm not sure I'm up to the expense and labor involved.  Is anyone aware 
of how basements were put in before we poured concrete, and excavated 
with backhoes?  Because frankly, if I could get around the expense of a 
concrete contractor/major excavation, and the labor was not too terribly 
skilled- I would go for a basement.  In lieu of that- I have this idea.  
Around the perimeter of the house, I would dig 3ft wide holes down below 
the freeze line, and then pour a concrete pier extending 3ft above 
grade.  In between the piers, I would lay a 3ft wide 'stone' wall made 
from salvaged concrete slabs over 4in of aggregate in a shallow trench:

Cutaway view from above-

                      interior of 
                          wall
[=====]=================[=====]=================[=====]
[pier ]                 [pier ]                 [pier ]
[     ] 'stone' wall    [     ]  'stone' wall   [     ]
[=====]=================[=====]=================[=====]
                      exterior of 
                          wall

Cutaway view from side-

 
 |                             || <- Protective Lime based 
 |                             ||    plaster for exterior
 |                             || 
 |                             ||
 |            cob              ||   
 |                             ||
 |                             ||
 |                             ||
 |                             ||
 |=============================||   
 |        Bond Beam            ||
 |^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^|                   
 |                              | ->Stone Wall           
 |         <- 3ft ->            |                     
 |                              | ================> grade level
 00000000000000000000000000000000 ->4in of aggregate

(not at all to scale!)

I would then tie the whole wall and pier structure together with a 
single concrete bond beam, poured both over the wall and the piers.  The 
cob walls would then sit on top of the bond beam.  Does this seem like a 
sound plan?  Can anyone suggest improvements to the plan?


Second; design.  I have this notion of "whole-house" design, where the 
house is a machine, and with proper maintenance could theoreticaly last 
forever...but anyway- the total plan encompasses a solar green house 
attached to the first floor, with vents to draw in the warm air.  The 
first floor will be cob for thermal heat retention, and the second floor 
Straw Bale for insulative heat retention.  The greenhouse will also 
function as a summer kitchen (solar stove) to avoid heat accumulation in 
the main living space.  New England is rather pleasant in the summer 
with cooler night temperatures, so I'm not too concerned about cooling, 
just not getting hot.  So my question is what moisture concerns should I 
expect vis-a-vis the greenhouse attached to the outside of a cob 
structure?  Has this been done anywhere, and how is it fairing?  I'm 
thinking that the the foundation I've mentioned should have no 
difficulty in supporting a second story made from SB, does that seem 
accurate?  Also, in this configuration, will I be able to construct a 
roof overhang wide enough to protect the cob first floor?  I'm also 
having an internal debate over the flooring for the first floor- I'd 
like to do some in floor radiant heating where I have coils full of 
water, being heated by running through the wall next to the hearth, 
imbedded in the floor throughout the first floor.  How much would 
something like that degrade the integrity of a cob wall, and would it be 
a practical application for an earthen floor in Southern N England?  
Okay, I'm pretty much done for the moment, let me know what you all 
think.  Thanks much.

Grace


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