Is this a logical solution to cob in cold climates?

I love cob....always have. But we will building near Springfield Missouri...where it gets darn cold. So I had let my cob dreams go to the wayside because of the temperature. But it kept nagging me because I love the cob homes. Is this a feasible solution for the insulation issue?

Basically using a large tree post or similar, use thatch to connect the two posts creating an inner pocket. Fill the inner pocket with insulation material (lava rock would be the easiest to obtain for us I think) then coating both sides with cob.

When you say "thatch," do you mean "wattle"? As in, a woven arrangement of thin branches?
Surely you don't mean bundles of parallel straw or reeds? How do intend to hold them in place?


Lots of people have cobbed the outside of strawbale structures. Do you not like that method?

Sorry, by thatch I meant wattle. Oops.

I do like strawbale but have met someone with a strawbale home and heard the horror stories. Bugs being the biggest problem.

Maha, where are you getting the information that COB mass needs insulation for your climate zone, 5 I think it is? What are your average winter time lows? And Summer highs? It can be too far from mine here is KS 10/85 F, zone 4. Mass like COB insulates by different mechanics than insulation like straw most do not understand. Please post some data showing the concern?

I think I found an insulation cure that maintains the monolithic structure of cob. I will be building this spring / summer if you would like to come by and see what I am up to. I will be using pumice instead of sand on the outer ⅔ of my upstate NY cob building project, and sand on the inner ⅓. In the model bricks I built and the model cob home I made with both sand and pumice, the bricks/ parts of the house made with pumice lasted through a whole wet and subzero winter on my back porch without disintegrating as the sand cob bricks did. So not only is pumice insulatetive it makes a stronger cob!
The only thing I have to work out before I break ground is the basement question. I will be doing water collection from my roof, and because of our sub zero winters, I need to put the water collection tank indoors. I thought it would be cost and labor efficient to put it in a basement . However I have never seen a cob house basement. I do not see why I can not build a stem wall basment height 5'in the ground. But that is for another post probably... have to figure where to put the question.
Suzanne Cornell

I love your idea.
Earthbags filled with perlite/lava rock.
Then a post and beam for the roof.
And for the floor, you can use the same earthbag filled with perlite and then covered with cob/earthen floor.

I will even throw in a floor plan.
6 big room, each room 12ft by 12ft entire structure is only 800sqft.