[Cob] purpose of straw

[Stacey]

Outside of tensile strength, straw is also very useful
to add insulation to cob walls.  

If you are trying for natural conditioning (passive
solar) design, this is especially important for north
facing walls.  In fact, to build the entire north wall
out of straw bales is not a bad idea.  But then again,
in Georgia, you might not need that so much:!


> What is the purpose of straw in a cob mix? Nobody
> seems to "really  
> know" what the role of straw is anyway. Is it there
> to hold the cob  
> together while the wall is still wet (like a free
> form), or to keep  
> the wall from crumbling incase it cracks later (like
> reenforcement),  
> or to allow air/water to move through the wall
> (because straw is  
> hollow)? The problem is that nobody knows the reason
> they used straw  
> because they didn't leave behind notes on how and
> why they built that  
> way, and it's been a while since they lived here.
> What do they do in  
> Africa? Do they use straw "in" the cob? Can any
> other plants be used  
> as tensile such as long grasses? I'm almost ready to
> start cobbing  
> but straw is just unavailable in GA right now, and
> what straw there  
> is has a very high price on it. I'm not willing to
> pay three times  
> the price for it if there's a substitution. I would
> love to just go  
> out in the field and get some tall grass if it would
> suffice. It's a  
> heck of a lot cheaper!
> 
> Chow,
> Damon Howell
> North Georgia, US
> 
> 
> 


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