I've been researching natural building methods for the past few years. Each time I think I've found the method I want to use, I come across information that makes me second guess myself.
In a nutshell:
Cob - Perhaps not the best choice for Vermont winters
Straw bale - moisture, mice problems. Read an account here on permies where the person said "a friend of mine helped dismantle a year-old straw-bale wall in the US, and found the whole interior hollowed out by happy nesting mice".
Cordwood - Wife and I don't care for the look
Ok, so I guess those are really the only methods I've seriously looked at, but I've gone back and forth several times.
I really like the idea of cob, the looks, the idea of sculpting your home, the spirituality of the process. I've wondered if there are ways to better insulate a cob home with natural materials (double wall of some sort, yet twice the work). I understand the immense importance of site design and layout when building with cob.
I guess my question with this post boils down to insulating a cob home. Any advice? (some of you may notice I've asked a similar question before, I'm feeling a little frustrated)
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I suggest you look at compressed earth block and rammed earth.
The rammed earth bit works using forms like cement, and a soil mix is tamped down in place. The portland or lime stabilised versions can be as durable as concrete. Compressed earth blocks is the same idea, but pressed into blocks or bricks or tiles, with the ratio of clay to soil adjusted for the needed physical characteristics.
These building materials can be used in ancient and modern masonry styles, making it easy to explain to permit inspectors.
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There are some other options to consider... light-clay straw, hempcrete... if you really like the idea of mass inside insulation in the walls, maybe earthbag with insulatiion-filled bags on the exterior?
I am working through this decision process myself..
I have to believe that strawbale your friend saw had some serious design and/or build errors. Armoring against rodents is not optional. A fibreglass filled wall will also become a rat colony in no time, if they have any way to get in..
While it would technically be possible to enclose a cob house in another insulating structure, it doesn't sound like a great idea to me given the time involved, and the amount of inside space consumed by the cob. I would rather add thermal mass to foundation/floors and maybe a cob bench(rmh?), and rely otherwise on the insulation.
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