Honken wrote:
Some questions:
Considering my climate (70-90F summers, 0-20F winters, lots of rain), is there any modification I would need to do to my cob-mix?
My main concern is spring/autumn where we have periods of constant rain. I know that adobe buildings in desert climates can last for millenia, however I've never seen any in areas of rain and snow.
If I were to have the building semi-underground, so that one wall would be against soil, would I need to use polyethylene or would the cob/adobe made from the same soil work by itself? I've been reading a bit of Oehler's book, but so far I haven't stumbled across anything suggesting the use of cob/adobe.
I'm fairly new to building and have lots to learn, any help is greatly appreciated. 
Hello Honken,
It sounds like your area is not a problem, you just should become more exact upon what it is, you really want to build. For Earth sheltered structures -Yes, you will need a moisture barrier ! Mr. Oehler's PSP method - while Great in a pinch or for emergency structures, if you have a few extra days to build in & a little bit of funds, there are much better and very permanent wall selections, certainly better than wood - let alone plain, Adobe Blocks or cob in that situation.
First About Above Ground: When we build a Georgia Adobe Structure, we always insulate the structure - be that within the structures walls, or on the outside & all depending upon just what were building. For example: If were building an Adobe Block Wall , we could easiest have 6 inches of closed cell foam insulation sprayed onto the outside of the building walls, just after the wall construction was completed. This would give us, the thermal mass desired inside and the
water tight structure outside. A simple connection of wire lath , mortared into the Adobe Blocks joints, provides ample connection for the foam to hold onto the wall and the exterior finish is done much as a spray stucco finish.
One could also lay your Adobe Block, so as to have a hollow middle area, that would incorporate a foam sheet core laid within it but, rarely is that a wise choice , as it cuts your 2 Block - Adobe wall's Thermal Mass, into 2 halves and also requires more engineering , just to stabilize the walls load bearing ability; as well, as one must also include, that admixture at least into the manufacture, of your outside Adobe Blocks ingredients.
If your building above ground your going to need a proper foundation and also a stem wall , so as not to have wicking of moisture into your Clay / Sand wall mix , when rains flood onto the outside wall of the building, so don't start laying Adobe's until your above the 500 year flood level.
Underground or Earth Sheltered Structures: If your building sub-terrainialy and you want to use
Carbon -0- Earth Mixes again, as your selected material, your going to need a permanent form, just to hold that earthen material together. For most single story Georgia Adobe Structures , we choose used automobile tires , as that they last for centuries , when tires are buried and plastered , they don't give off any adverse emissions and when pounded with a proper Earth mix you basically have a 300 to 400 pound steel belted brick. Outside of that, one will of
course insulate the building with more closed cell foam sprayed or sheet form and provide a proper moisture barrier lining, to create a sealed envelope structure, inside the earth.
I hope, some of that helps you with your choices & remember to only build where the location is 100% paid for - secluded & not regulated by government building inspections, or you are very likely if you choose "Alternative Materials " to get to spend lots of your money on over engineering , re-drawings and
concrete in place of Earth.
Best Regards,
Joe Woodall, Rogue Eco-Architect & Managing Partner
Georgia Adobe Rammed Earth & Renewable Energy
Commerce, Georgia 30530 CSA
001-706-363-6453
Http://www.georgiaadobe.com 
