[Cob] plastic jugs in walls?

[john fordice]

Ed,
Based on historic seismic survival of adobe buildings, and some  
research that was also done for adobe,  a wall height to thickness  
ratio of 7 to 1 has good seismic survival capacity.  In the absence  
of similar tested data for cob, I use this ratio when designing and  
building cob walls.  At 7" thick, this would give a height limit of  
7x7 = 49".  What is the height of the walls you are describing?
john fordice

On Dec 10, 2009, at 7:16 PM, Henry Raduazo wrote:

> 	If you are making good quality cob the wall can be as thin as 7  
> inches. At cob cottage in Coquille they have been retying bales of  
> straw and chain sawing them half. The half bales are stuck in the  
> wall and this results in an insulation layer on the outside of 7  
> inch thick cob walls. It saves tones of cob.
> 	I just finished putting a cob wall on top of two cinderblock  
> retaining walls 7.5 inches thick. Two 7 inch thick cob walls  
> support 12 foot living roof 50 pounds per square foot.  They are  
> short cob walls with a good overhang so I expect no trouble  
> supporting the weight.
> Ed
> On Dec 10, 2009, at 2:46 PM, john fordice wrote:
>
>> Tys,
>> I'll venture to say (without really being able to prove it) that  
>> it will weaken the wall.  A cob wall gets it  strength by being  
>> thick.  A structure resists forces acting on it by being made as  
>> continuous as possible.  Making a void in the wall will create a  
>> weak spot which compromises the continuity of the structure.    I  
>> would not do anything which creates voids in the cob based on this  
>> reasoning.
>> john fordice
>>
>> On Dec 10, 2009, at 10:07 AM, Tys Sniffen wrote:
>>
>>> So, as my walls get up over 7 feet high, I'm starting to remember  
>>> how lower
>>> down, when I had them laying around, I would toss in the  
>>> occasional urbanite
>>> chunk to take up some space.
>>>
>>> Now I'm starting to think about tossing in some one gallon  
>>> plastic jugs
>>> (vinegar jugs, that are slightly thicker plastic than the common  
>>> 1 gal milk
>>> jug) again, to take up space, but also I'm thinking having a void  
>>> in the
>>> wall that size could insulation in a way, and, of course, would  
>>> make my tall
>>> parts a bit lighter.
>>>
>>> Does that sound like a bad idea to anyone?
>>>
>>> Tys
>>>
>>>
>>>
>>>
>>> _______________________________________________
>>> Coblist mailing list
>>> Coblist at deatech.com
>>> http://www.deatech.com/mailman/listinfo/coblist
>>
>>
>> _______________________________________________
>> Coblist mailing list
>> Coblist at deatech.com
>> http://www.deatech.com/mailman/listinfo/coblist
>