Cob - Insulation - Cob sandwich was RE: Cob Re: Beers cause cordwood dreams

[Will Firstbrook WCB of BC]

Hi Michael &  M J Epko,

Thanks for your e-mails. Very good points to ponder regarding the cob
insulation cob sandwich. I enjoy the exchange of ideas.

Regarding the probable lack of bonding between the cordwood and cob
perhaps one can notch both ends of the logs so there is a mechanical
connection to the cob. Thus there should be little slippage between the
inside and outside cob walls.

Regarding the load bearing capability of this arrangement, I agree I
would feel a lot more comfortable to use it in a post and beam
structure. Unless the cob is made extra thick which would involve a lot
more work.<nah>.   

These ideas are even more sensitive to water failure than normal cob.
Thus the normal cob fundamental rules will still apply here, such as 1st
2 feet from ground are not made of cob and a generous roof overhang so
the cob wall never gets saturated with water. I never want to see cob
oozing like peanut butter from a finished structure.

 |     |               |        ||
 |     |               |        ||
 |     |               |        ||
 |     |    Straw &    |        ||
 |Cob  |    Sawdust    |  Cob   || <- Protective Lime based 
 |  _  |_______________|__   _  ||    plaster for exterior
 | | \_/                  \_/ | || 
 | |  _  Cord wood notched _  | ||
 | |_/ \__________________/ \_| ||   
 |     |               |        ||
 |  _  |_______________|__   _  ||
 | | \_/                  \_/ | ||
 | |  _  Cord wood notched _  | ||
 | |_/ \__________________/ \_| ||   
 |     |               |        ||
 |     |               |        ||
 |^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^   
 |     Stone & Mortar           |
 |       Foundation             |
 |                              |
 |                              |
 00000000000000000000000000000000

ASCII ART Courier Font

Not to scale

I really like the idea of creating the insulation layer as where I am
going to build in the BC interior has some cold winters. My other
thought is Strawbale (load bearing or post & beam) with a foot of cob on
the interior for mass, utility and creative detailing.

I agree a test wall would be a good idea prior to building our main
structure. Those fiber cement failure pictures are an eye opener. 

Regards, 
Will

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