Cob: messed up building / mechanical mixing

[Shannon C. Dealy]

On Fri, 15 Aug 2003, Donna Strow wrote:

[snip]
> My parents want to know, what happens if you have a workshop and the
> building is messed up?
> I told them I assumed the whole thing was about taking reasonable risks and
> fixing whatever went wrong... right?

Depends on what you mean by "messed up", a bad design is hard to fix,
but many construction mistakes aren't that big a deal, especially with
cob -- I underestimated the shrinkage and settling of a wall and didn't
set the support beam over a window high enough above it, so over time it
eventually started putting weight on the top of the window frame.  To fix
it I just grabbed a hammer and chisel to remove cob from below the entire
base of the window, this allowed it to shift down as the beam above it
settled, one of these days (now that the wall has finished shrinking and
settling), I should fill in the area at the base of the window with cob to
seal it up.

> My father says, if I don't have an army of hippies like my mentors did, I
> should tool up with a cement mixer (he says fine for cob) and a pickup truck
> first (total $1500.)  He's right about one thing -- I hate getting my feet
> muddy!
[snip]

A cement mixer won't work for cob (it's been tried repeatedly), the straw
won't mix in.  For mechanical mixing people have reported some success
with mortar mixers (but never make more than 1/2 load at a time, the straw
in the cob will overload the unit), roto-tillers (I've been meaning to try
this one since I was recently given one), and tractor/skid-loader/bobcat
(basically anything with a bucket, though the skidloader/bobcat works
better since you can spin them around on top of the pile for mixing)

Shannon C. Dealy      |               DeaTech Research Inc.
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