Cob: RE: RE: RE: small cob housing

Fri Jul 4 01:58:09 CDT 2003

Agreed. I understood her to mean cob that was wet enough to pump into forms.
Ive seen shuttering used on relatively dry mixes that dried quickly. Just
assuming youd have a bear of a time drying out that wet of a mix. What
consistency is the mix you are using?

J
-----Original Message-----
From: owner-coblist at deatech.com [mailto:owner-coblist at deatech.com]On Behalf
Of Abe Connally
Sent: Friday, July 04, 2003 12:04 AM
To: coblist at deatech.com
Subject: Cob: RE: RE: small cob housing

Well,

A lot of this has to do with your climate and your mix.  Our cob dries well
within a few days, and even in a form, in dries withina week or so.  We add
a little portland cement to help the curing process, and that helps to
create a stronger mix when wet as well.

Abe
-----Original Message-----
From: owner-coblist at deatech.com [mailto:owner-coblist at deatech.com]On Behalf
Of Joe Skeesick
Sent: Thursday, July 03, 2003 5:29 PM
To: coblist at deatech.com
Subject: Cob: RE: small cob housing
Some people have tried cement mixers to mix cob but the standard drum style
mixer just isnt a good tool for the job and you end up being able to mix
cob with your feet faster. A mortar mixer works much better but still ends
up with a wet mix and the straw has to be mixed in manually or it fouls the
blades. Basically what you need to do to mix large amount of cob is to
replicate the trodding action of foot mixing.

Traditionally cob was made in an animal lot over time, allowing animals cows
and or horses to trod over an area for months pressing the elements together
like kneading dough. We now try to replicate this with our own feet and a
tarp. It takes a lot of work to make relatively small batches. The best way
to mimic this process with machines is quite simply replacing horse hooves
with horsepower. This is often done with a tractor (hence called tractor
cob). Ive found personally that the very best small-scale cob mixing unit
is a bobcat. The bobcat because of its counter rotating wheel steering can
simply spin in place around the clay/sand/straw mix, churning it squishing
it together under the weight of the unit. The added benefit of the front end
loader on the bobcat to both scoop the mix back into a pile and then deliver
it within reach of folks working on an elevated wall section make it a great
tool to have. It also fits well in a tight building site. You can of course
use a standard tractor or even a truck but they both have drawbacks (the
truck in particular) The important aspect of mixing cob though is that the
individual elements have to be compressed together to get everything to bind
well. Tumble mixing will never get you a really well bonded mix. Save the
cement mixer for the lime plaster. It works great for that.

On the topic of pouring cob
 well, its not really cob at that point. Cob
takes quite some time to dry out and if you had a mix that was wet enough to
pour and you trapped it inside forms Im afraid it would take months to dry
enough to support its own weight to allow the forms to be removed. Im
guessing here since Ive no experience at all in that area. When I discussed
building cob relatively quickly please note the relatively aspect. There
is still a drying time that is needed for each lift to be able to support
more cob above without schlumping :-) (basically collapsing under the
weight of new cob above it). Still, even with that drying time, the home I
spoke of built by Kevin McCabe took only 3 months to build the walls on a
3200 square foot home. The entire project took 15 months with him and 2
other workers on the job. The home was built to a high level of finish as it
was originally built with immediate resale in mind. (he and his wife changed
their minds once it was built and moved in instead). That is the sort of
relative quickly construction I was referring to.

Best of luck with your project however you decide to build it.

Joe

-----Original Message-----
From: owner-coblist at deatech.com [mailto:owner-coblist at deatech.com]On Behalf
Of Mary Hooper
Sent: Thursday, July 03, 2003 10:15 PM
To: coblist at deatech.com
Subject: Cob: small cob housing

Now I'm going to try to send this message to the list instead of just the
one person who brought it up!!!
snip snip snip:::
Cob buildings can be large, they can be made with large machinery and
theycan be made relatively quickly. However, it is also a human scale
technologythat can be made almost completely by hand with simple tools and
.... ::end snip

Now, there's a thought I had not had.... using large machinery.... has
anyone used a cement mixer instead of feet to mix the mud????
I imagine a big truck size mixer and the construction guy saying "You want
me to mix WHAT in it?" and the forms people saying "You want to me to pour
WHAT in my forms?"
Anyone have any wisdom to impart for either sitution? Would a large poured
wall dry without cracking? Would those of us who have tricky knees and
reduced energy levels benefit from thinking "outside the box" on this? Not
to go fully industrial strength, but how could we utilize modern equipment
to make the job easier on our old joints and/or speed up the work?
Mary in NC
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Agreed. I understood her to mean cob that was wet enough to pump into
forms. I’ve seen shuttering used on relatively dry mixes that dried quickly.
Just assuming you’d have a bear of a time drying out that wet of a mix. What consistency
is the mix you are using?<o:p></o:p>

<p class=MsoNormal><span class=EmailStyle17><font size=2 color="#993366"
face=Arial><span style='font-size:10.0pt;mso-bidi-font-size:12.0pt;font-family:
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<p class=MsoNormal><span class=EmailStyle17><font size=2 color="#993366"
face=Arial><span style='font-size:10.0pt;mso-bidi-font-size:12.0pt;font-family:
Arial'><![if !supportEmptyParas]> <![endif]><o:p></o:p></span></font></span></p>

<p class=MsoNormal><span class=EmailStyle17><font size=2 color="#993366"
face=Arial><span style='font-size:10.0pt;mso-bidi-font-size:12.0pt;font-family:
Arial'>J<o:p></o:p></span></font></span></p>

<p class=MsoNormal style='margin-left:.5in'><font size=2 color=black
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma;color:black'>-----Original
Message-----<br>
<b><span style='font-weight:bold'>From:</span></b> owner-coblist at deatech.com
[mailto:owner-coblist at deatech.com]<b><span style='font-weight:bold'>On Behalf
Of </span></b>Abe Connally<br>
<b><span style='font-weight:bold'>Sent:</span></b> Friday, July 04, 2003 12:04
AM<br>
<b><span style='font-weight:bold'>To:</span></b> coblist at deatech.com<br>
<b><span style='font-weight:bold'>Subject:</span></b> Cob: RE: RE: small cob
housing</span></font></p>

<p class=MsoNormal style='margin-left:.5in'><font size=3 face="Times New Roman"><span
style='font-size:12.0pt'><![if !supportEmptyParas]> <![endif]><o:p></o:p></span></font></p>

<p class=MsoNormal style='margin-left:.5in'><font size=2 color=blue face=Arial><span
style='font-size:10.0pt;font-family:Arial;color:blue'>Well,</span></font><font
color=black><span style='color:black;mso-color-alt:windowtext'><o:p></o:p></span></font></p>

<p class=MsoNormal style='margin-left:.5in'><font size=3 color=black
face="Times New Roman"><span style='font-size:12.0pt;color:black'> </span></font><font
color=black><span style='color:black;mso-color-alt:windowtext'><o:p></o:p></span></font></p>

<p class=MsoNormal style='margin-left:.5in'><font size=2 color=blue face=Arial><span
style='font-size:10.0pt;font-family:Arial;color:blue'>A lot of this has to do
with your climate and your mix.  Our cob dries well within a few days, and
even in a form, in dries withina week or so.  We add a little portland
cement to help the curing process, and that helps to create a stronger mix when
wet as well.</span></font><font color=black><span style='color:black;
mso-color-alt:windowtext'><o:p></o:p></span></font></p>

<p class=MsoNormal style='margin-left:.5in'><font size=3 color=black
face="Times New Roman"><span style='font-size:12.0pt;color:black'> </span></font><font
color=black><span style='color:black;mso-color-alt:windowtext'><o:p></o:p></span></font></p>

<p class=MsoNormal style='margin-left:.5in'><font size=2 color=blue face=Arial><span
style='font-size:10.0pt;font-family:Arial;color:blue'>Abe</span></font><font
color=black><span style='color:black;mso-color-alt:windowtext'><o:p></o:p></span></font></p>

<p class=MsoNormal style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:
12.0pt;margin-left:.5in'><font size=2 color=black face=Tahoma><span
style='font-size:10.0pt;font-family:Tahoma;color:black'>-----Original
Message-----<br>
<b><span style='font-weight:bold'>From:</span></b> owner-coblist at deatech.com
[mailto:owner-coblist at deatech.com]<b><span style='font-weight:bold'>On Behalf
Of </span></b>Joe Skeesick<br>
<b><span style='font-weight:bold'>Sent:</span></b> Thursday, July 03, 2003 5:29
PM<br>
<b><span style='font-weight:bold'>To:</span></b> coblist at deatech.com<br>
<b><span style='font-weight:bold'>Subject:</span></b> Cob: RE: small cob
housing</span></font><font color=black><span style='color:black;mso-color-alt:
windowtext'><o:p></o:p></span></font></p>

Some people have tried cement mixers to mix cob but
the standard drum style mixer just isn’t a good tool for the job and you end up
being able to mix cob with your feet faster. A “mortar mixer” works much better
but still ends up with a wet mix and the straw has to be mixed in manually or
it fouls the blades. Basically what you need to do to mix large amount of cob
is to replicate the trodding action of foot mixing.<o:p></o:p>

<p class=MsoNormal style='margin-left:.5in'><span class=EmailStyle16><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;mso-bidi-font-size:
12.0pt;font-family:Arial'> <o:p></o:p></span></font></span></p>

Traditionally cob was made in an animal lot over
time, allowing animals cows and or horses to trod over an area for months
pressing the elements together like kneading dough. We now try to replicate
this with our own feet and a tarp. It takes a lot of work to make relatively
small batches. The best way to mimic this process with machines is quite simply
replacing horse hooves with horsepower. This is often done with a tractor
(hence called “tractor cob”). I’ve found personally that the very best
small-scale cob mixing unit is a bobcat. The bobcat because of its counter
rotating wheel steering can simply spin in place around the clay/sand/straw
mix, churning it squishing it together under the weight of the unit. The added
benefit of the front end loader on the bobcat to both scoop the mix back into a
pile and then deliver it within reach of folks working on an elevated wall
section make it a great tool to have. It also fits well in a tight building
site. You can of course use a standard tractor or even a truck but they both
have drawbacks (the truck in particular) The important aspect of mixing cob
though is that the individual elements have to be compressed together to get
everything to bind well. Tumble mixing will never get you a really well bonded
mix. Save the cement mixer for the lime plaster. It works great for that.<o:p></o:p>

<p class=MsoNormal style='margin-left:.5in'><span class=EmailStyle16><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;mso-bidi-font-size:
12.0pt;font-family:Arial'> <o:p></o:p></span></font></span></p>

On the topic of pouring cob… well, it’s not really
cob at that point. Cob takes quite some time to dry out and if you had a mix
that was wet enough to pour and you trapped it inside forms I’m afraid it would
take months to dry enough to support its own weight to allow the forms to be
removed. I’m guessing here since I’ve no experience at all in that area. When I
discussed building cob “relatively quickly” please note the “relatively”
aspect. There is still a drying time that is needed for each lift to be able to
support more cob above without “schlumping” J (basically collapsing under the weight of new cob above
it). Still, even with that drying time, the home I spoke of built by Kevin
McCabe took “only” 3 months to build the walls on a 3200 square foot home. The
entire project took 15 months with him and 2 other workers on the job. The home
was built to a high level of finish as it was originally built with immediate
resale in mind. (he and his wife changed their minds once it was built and
moved in instead). That is the sort of “relative quickly” construction I was
referring to.<o:p></o:p>

<p class=MsoNormal style='margin-left:.5in'><span class=EmailStyle16><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;mso-bidi-font-size:
12.0pt;font-family:Arial'> <o:p></o:p></span></font></span></p>

Best of luck with your project however you decide to
build it. <o:p></o:p>

<p class=MsoNormal style='margin-left:.5in'><span class=EmailStyle16><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;mso-bidi-font-size:
12.0pt;font-family:Arial'> <o:p></o:p></span></font></span></p>

<p class=MsoNormal style='margin-left:.5in'><span class=EmailStyle16><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;mso-bidi-font-size:
12.0pt;font-family:Arial'>Joe<o:p></o:p></span></font></span></p>

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<p class=MsoNormal style='margin-left:.5in'><span class=EmailStyle16><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;mso-bidi-font-size:
12.0pt;font-family:Arial'> <o:p></o:p></span></font></span></p>

<p class=MsoNormal style='margin-left:.5in'><span class=EmailStyle16><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;mso-bidi-font-size:
12.0pt;font-family:Arial'> <o:p></o:p></span></font></span></p>

<p class=MsoNormal style='margin-left:.5in'><span class=EmailStyle16><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;mso-bidi-font-size:
12.0pt;font-family:Arial'><span style="mso-spacerun: yes"> </span><o:p></o:p></span></font></span></p>

<p class=MsoNormal style='margin-left:.5in'><span class=EmailStyle16><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;mso-bidi-font-size:
12.0pt;font-family:Arial'> <o:p></o:p></span></font></span></p>

<p class=MsoNormal style='margin-left:.5in'><span class=EmailStyle16><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;mso-bidi-font-size:
12.0pt;font-family:Arial'> <o:p></o:p></span></font></span></p>

<p class=MsoNormal style='margin-left:1.0in'><font size=2 color=black
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma;color:black'>-----Original
Message-----<br>
<b><span style='font-weight:bold'>From:</span></b> owner-coblist at deatech.com
[mailto:owner-coblist at deatech.com]<b><span style='font-weight:bold'>On Behalf
Of </span></b>Mary Hooper<br>
<b><span style='font-weight:bold'>Sent:</span></b> Thursday, July 03, 2003
10:15 PM<br>
<b><span style='font-weight:bold'>To:</span></b> coblist at deatech.com<br>
<b><span style='font-weight:bold'>Subject:</span></b> Cob: small cob housing</span></font><font
color=black><span style='color:black;mso-color-alt:windowtext'><o:p></o:p></span></font></p>

<p class=MsoNormal style='margin-left:1.0in'><font size=3 color=black
face="Times New Roman"><span style='font-size:12.0pt;color:black'> </span></font><font
color=black><span style='color:black;mso-color-alt:windowtext'><o:p></o:p></span></font></p>

<p class=MsoNormal style='margin-left:1.0in'><font size=3 color=black
face="Times New Roman"><span style='font-size:12.0pt;color:black'> </span></font><font
color=black><span style='color:black;mso-color-alt:windowtext'><o:p></o:p></span></font></p>

Now I'm
going to try to send this message to the list instead of just the one person
who brought it up!!! <o:p></o:p>

snip snip
snip::: 
Cob buildings can be large, they can be made with large machinery and 
theycan be made relatively quickly. However, it is also a human scale 
technologythat can be made almost completely by hand with simple tools and 
.... ::end snip 
 
Now, there's a thought I had not had.... using large machinery.... has 
anyone used a cement mixer instead of feet to mix the mud???? 
I imagine a big truck size mixer and the construction guy saying "You want 
me to mix WHAT in it?" and the forms people saying "You want to me to
pour 
WHAT in my forms?" 
Anyone have any wisdom to impart for either sitution? Would a large poured 
wall dry without cracking? Would those of us who have tricky knees and 
reduced energy levels benefit from thinking "outside the box" on
this? Not 
to go fully industrial strength, but how could we utilize modern equipment 
to make the job easier on our old joints and/or speed up the work? 
Mary in NC<o:p></o:p>

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