Cob: Re: Re: greenhouse start

[storm]

Our greenhouse startup, we don't have any photos yet, but hopefully soon. As to the mixture that I have been using, its hard to pass on the recipe, for we all have different ingredients in different parts of the country, but basically the mixture has about 20-25% clay to 60% sand and then a generous amount of straw and water. With a mixer I tend to keep the mix fairly wet, almost like a plaster. I make some large mixes in the morning and the cob can sit all day, until your ready to put it on a wall. The reasoning behind this that its easier on the mixer to have more water, otherwise it can get gummed up and unbalance the unit.  For the same reason I first fill the mixer with water, then clay, let it mix for about 5 minutes, then I add my soil (or soils), and lastly i shake in the straw.  After I  unload the wet cob onto a large board I may stomp in even more straw depending on the wetness and density of the mix. Yes it is more efficient, but its alot noisier too. I try to make a large amount of cob at once i.e. 4-8 wheelbarrows full.  Then I can build in peace.
    As to soil against a cob wall, I would not recommend it. You might try a dry stack rock wall a foot high and then add cob on top of that. If you don't fully trust your masonry skills, add some mortar. Your cob needs to be off the ground, between 12-24" depending on severity of rainfall and snow. I hope this helps, sincerely Anikke

Anikke's been making it mostly, we just got a large fancy plaster mixer (Crown, spiral paddles, model S10S) to mix cob and plasters-- hopefully like alot. The mixes want to be a little wet, but stomping in straw is easy-- also a good idea because the mixer does break the long straw fibers down some. 

I don't think we'll put straw into the crevasse between the two cob walls. The sticks holding the two walls together will for sure be as dry as possible-- yes shrinking goes about 12: 1. Using a green log or stick, say a twelve inch in diameter log round for a cord-wood/cob wall, if it's green it will shrink about an inch in diameter. 12 to 11. Definitely a bad idea I'd think. I had in mind splitting any dry log round into sticks strong enough to hold a shelf on one side if it sticks out a foot or two, maybe for kids to monkey on. I think any wood would do. Fire hazard? Yeah, and the wood roof eves. This being an unattatched outbuilding I'm willing to put up with a little more risk I guess, like the sticks poking out of the wall everywhere holding wooden drying racks, sometimes with nice dry herbs and such. BUT, this is cob and those cob walls will not burn even if everything else does, better than most buildings I'd say. For the roof eves, I don't know what else to make a nice overhang with besides wood. If anyone solves that problem without going to steel or something industrial that would probably save many a home.  

As far as efficiency goes-- always remember there's nothing more efficient than doing it without petro-chemicals and the whole thing. We have made a serious decision in compromising the right way to do things with the use of our big tool in hopes to effect a transitional paradigm only. Everyone must think there way through these troubled times. 

For your wall with garden soil piled up against it-- you could try it with the knowledge it may fail. Otherwise try perhaps a water impermeable layer bewtween the soil and dry cob wall? A dry stack of bricks, or sticks verticly and then a layer of thick plastic or EPDM (rubber pond liner) to create a ventilation gap between the cob and the impermeable layer? I think in our greenhouse we'll use EPDM either right up against the cob or with a small gap there somehow. The epdm should only have to be up against the walls and not on the ground. We have a sandy soil that carries water away and down well. We'll probably make a large pool with rock and cob lined with epdm for a cistern inside the greenhouse. 

Progress has been slowed, we're off to Telluride for the bluegrass fest. See you in a couple of weeks! Steve





----- Original Message ----- 
  From: drhelp 
  To: coblist at deatech.com 
  Sent: Tuesday, June 12, 2001 9:43 PM
  Subject: Cob: Re: greenhouse start


  Hi there. Do you have photos to show? And what, exactly is the mix you put into the cement mixer? Would you tell the approximate proportions of ingredients, and also how long the cement mixer has to mix to get the consistency for the cob?
  Do you plan on putting insulation between the two cob walls?
   
  Will the sticks be a fire hazard? How thick and what kind and are they fully dried? Will they shrink and cause problems? Your methods sound so efficient, in comparison with jumping around on muck/straw on tarpaulins...how come nobody's thought of this? Seems brill.
   
  Can you give more details, and if you scan photos in it will really help for those  of us who are researching but haven't done any of this yet. I'm about to start a cob wall...short, on one of my property boundaries. If I put soil right up against it, once it's cured, will the dampness of the soil cause the wall to reduce to muck?

  The wall, then, would delineate that boundary (neighbours are touchy about "encroachment") and serve to contain soil for garden on the sloped side of my property...IF the cob wil ldo that. The wall will be only about 3 feet high. Diana in Victoria
-------------- next part --------------
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META content="text/html; charset=iso-8859-1" http-equiv=Content-Type>
<META content="MSHTML 5.00.2614.3500" name=GENERATOR>
<STYLE></STYLE>
</HEAD>
<BODY bgColor=#ffffff>
<DIV><FONT face=Arial size=2>Our greenhouse startup, we don't have any photos 
yet, but hopefully soon. As to the mixture that I have been using, its hard to 
pass on the recipe, for we all have different ingredients in different parts of 
the country, but basically the mixture has about 20-25% clay to 60% sand and 
then a generous amount of straw and water. With a mixer I tend to keep the mix 
fairly wet, almost like a plaster. I make some large mixes in the morning and 
the cob can sit all day, until your ready to put it on a wall. The reasoning 
behind this that its easier on the mixer to have more water, otherwise it can 
get gummed up and unbalance the unit.  For the same reason I first fill the 
mixer with water, then clay, let it mix for about 5 minutes, then I add my soil 
(or soils), and lastly i shake in the straw.  After I  unload the wet 
cob onto a large board I may stomp in even more straw depending on the wetness 
and density of the mix. Yes it is more efficient, but its alot noisier too. I 
try to make a large amount of cob at once i.e. 4-8 wheelbarrows full.  Then 
I can build in peace.</FONT></DIV>
<DIV><FONT face=Arial size=2>    As to soil against a cob wall, I 
would not recommend it. You might try a dry stack rock wall a foot high and then 
add cob on top of that. If you don't fully trust your masonry skills, add some 
mortar. Your cob needs to be off the ground, between 12-24" depending on 
severity of rainfall and snow. I hope this helps, sincerely Anikke</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>Anikke's been making it mostly, we just got a large 
fancy plaster mixer (Crown, spiral paddles, model S10S) to mix cob and 
plasters-- hopefully like alot. The mixes want to be a little wet, but stomping 
in straw is easy-- also a good idea because the mixer does break the long straw 
fibers down some. </FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>I don't think we'll put straw into the crevasse 
between the two cob walls. The sticks holding the two walls together will for 
sure be as dry as possible-- yes shrinking goes about 12: 1. Using a green log 
or stick, say a twelve inch in diameter log round for a cord-wood/cob wall, if 
it's green it will shrink about an inch in diameter. 12 to 11. Definitely a bad 
idea I'd think. I had in mind splitting any dry log round into sticks 
strong enough to hold a shelf on one side if it sticks out a foot or two, maybe 
for kids to monkey on. I think any wood would do. Fire hazard? Yeah, and the 
wood roof eves. This being an unattatched outbuilding I'm willing to put up 
with a little more risk I guess, like the sticks poking out of the wall 
everywhere holding wooden drying racks, sometimes with nice dry herbs and such. 
BUT, this is cob and those cob walls will not burn even if everything else does, 
better than most buildings I'd say. For the roof eves, I don't know what else to 
make a nice overhang with besides wood. If anyone solves that problem without 
going to steel or something industrial that would probably save many a 
home.  </FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>As far as efficiency goes-- always remember there's 
nothing more efficient than doing it without petro-chemicals and the whole 
thing. We have made a serious decision in compromising the right way to do 
things with the use of our big tool in hopes to effect a transitional paradigm 
only. Everyone must think there way through these troubled times. </FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>For your wall with garden soil piled up against 
it-- you could try it with the knowledge it may fail. Otherwise try perhaps a 
water impermeable layer bewtween the soil and dry cob wall? A dry stack of 
bricks, or sticks verticly and then a layer of thick plastic or EPDM (rubber 
pond liner) to create a ventilation gap between the cob and the impermeable 
layer? I think in our greenhouse we'll use EPDM either right up against the cob 
or with a small gap there somehow. The epdm should only have to be up against 
the walls and not on the ground. We have a sandy soil that carries water away 
and down well. We'll probably make a large pool with rock and cob lined with 
epdm for a cistern inside the greenhouse. </FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>Progress has been slowed, we're off to Telluride 
for the bluegrass fest. See you in a couple of weeks! Steve</FONT></DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV>----- Original Message ----- </DIV>
<BLOCKQUOTE 
style="BORDER-LEFT: #000000 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px; PADDING-RIGHT: 0px">
  <DIV 
  style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B> 
  <A href="mailto:drhelp at home.com" title=drhelp at home.com>drhelp</A> </DIV>
  <DIV style="FONT: 10pt arial"><B>To:</B> <A href="mailto:coblist at deatech.com" 
  title=coblist at deatech.com>coblist at deatech.com</A> </DIV>
  <DIV style="FONT: 10pt arial"><B>Sent:</B> Tuesday, June 12, 2001 9:43 
PM</DIV>
  <DIV style="FONT: 10pt arial"><B>Subject:</B> Cob: Re: greenhouse start</DIV>
  <DIV><BR></DIV>
  <DIV><STRONG><FONT face="Tempus Sans ITC" size=4>
  <DIV><STRONG><FONT face="Tempus Sans ITC" size=4>Hi there. Do you have photos 
  to show? And what, exactly is the mix you put into the cement mixer? Would you 
  tell the approximate proportions of ingredients, and also how long the cement 
  mixer has to mix to get the consistency for the cob?<BR>Do you plan on putting 
  insulation between the two cob walls?</FONT></STRONG></DIV>
  <DIV><STRONG><FONT face="Tempus Sans ITC" size=4></FONT></STRONG> </DIV>
  <DIV><STRONG><FONT face="Tempus Sans ITC" size=4>Will the sticks be a fire 
  hazard? How thick and what kind and are they fully dried? Will they shrink and 
  cause problems? Your methods sound so efficient, in comparison with jumping 
  around on muck/straw on tarpaulins...how come nobody's thought of this? Seems 
  brill.</FONT></STRONG></DIV>
  <DIV><STRONG><FONT face="Tempus Sans ITC" size=4></FONT></STRONG> </DIV>
  <DIV><STRONG><FONT face="Tempus Sans ITC" size=4>Can you give more details, 
  and if you scan photos in it will really help for those  of us who are 
  researching but haven't done any of this yet. I'm about to start a cob 
  wall...short, on one of my property boundaries. If I put soil right up against 
  it, once it's cured, will the dampness of the soil cause the wall to reduce to 
  muck?<BR><BR>The wall, then, would delineate that boundary (neighbours are 
  touchy about "encroachment") and serve to contain soil for garden on the 
  sloped side of my property...IF the cob wil ldo that. The wall will be only 
  about 3 feet high. Diana in 
  Victoria</FONT></STRONG></DIV></FONT></STRONG></DIV></BLOCKQUOTE></BODY></HTML>