[Cob] ICF & rammed earth

[Dean Sherwin]

Well to me that's a very interesting idea, especially as I recently 
built a rammed earth wall and I have to say at this point it is rock 
hard.  You would still have to put up strong shuttering outside of 
the ICFs as the pressure of ramming the earth would send the 
polystyrene flying in an instant.  and don't forget you have to get 
up on the wall and ram down even with pneumatic tampers.  The cores 
in most cases might be a bit small for a good wall, and the ties be 
hard to work around. But to increase the insulation is a good - make 
that great - idea.  You might achieve the same thing more simply by 
simply lining the formwork with  sheets of styrofoam board, maybe 
push 'staples' or hoops of  stiff wire through to grip the 
earth.  But then you wouod hide the beautiful nature of the rammed 
earth.  Maybe put the insulation just on one side?
With rammed earth there does need to be some drying out, but nothing 
like cob as its only slightly moist.   (with my project a bit of it 
did seem too damp and I needed it to dry out to take the next layer 
so I drilled a bunch of holes in the ply formwork)   Another 
advantage of just putting insulation on one side?
remember to get the equivalent strength of 8" of  reinforced concrete 
you need maybe a 16" ? earth wall



>Message: 1
>Date: Mon, 19 Sep 2011 22:37:02 -0700 (PDT)
>From: Sky Orndoff <skyorndoff at yahoo.com>
>To: "coblist at deatech.com" <coblist at deatech.com>
>Subject: [Cob] Rammed earth in ICF Forms??
>Message-ID:
>         <1316497022.21982.YahooMailNeo at web161213.mail.bf1.yahoo.com>
>Content-Type: text/plain; charset=iso-8859-1
>
>Hey Everyone!
>
>I have been working on a conventional build alongside my cobwood 
>project, and have come to really like Insulated Concrete Forms 
>(ICFs) for their speedy, structural assemblage of a nice simple 
>building (google superform).? I also like that they can directly 
>hold plaster, and I like their thermal mass--insulation hybrid.? And 
>I like how accepted they are with building officials.? What I don't 
>like about the ICFs are the styrofoam itself and the concrete and 
>those things' negative effects on the environment.? However, the 
>durable, quite insulative, super-easy-to-construct nature of the 
>forms makes them maybe worth it, especially if we can do away with 
>the concrete.
>
>
>Here in Helena, Montana, it's quite dry, and horribly cold in the 
>winter, and so I was wondering what you all had to say about the 
>idea of filling ICFs with Rammed Earth.? As far as I know, Rammed 
>Earth has approximately the same compressive strength as Concrete 
>and similar (very little) tensile strength.? Its shatter strength is 
>lower, I believe, than Concrete, and it can fail if it gets and 
>stays wet.? Will I be constantly fighting moisture issues? Do you 
>expect failure? Horrible and hideous catastrophic results?? Or did I 
>hit on something smart?
>
>
>What I'd like from you all are ideas on testing/how to monitor 
>moisture levels inside the forms, ideas on how to avoid moisture 
>penetrating and accumulating inside the walls, and possibly ideas on 
>ways to back up rammed-earth's strength.
>
>What do you think?? Am I off my rocker, am I too apologetic to the 
>constructionary-industrial complex, or is this an idea worth exploring?
>
>Thanks a lot for your feedback!
>
>Sky
>
>www.earthartbuild.wordpress.com
>
>
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>End of Coblist Digest, Vol 9, Issue 120
>***************************************



Dean Sherwin CPE
Certified Professional Estimator
LEED Accredited Professional
CONSTRUCTION COST MANAGEMENT
3, Cherry Street
PO Box 11
Media, PA 19063-0011
(610)892 8860
fax (610) 892 7862
costman at verizon.net