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Kiko Denzer on Art


Cob: cob and cordwood

Briggs WebDesign bwd at coxinet.net
Thu Mar 6 16:18:07 CST 2003 

Cat,
You bring up some interesting points, which may or may not have relevence depending on your location and wood supply.

Cordwood traditionally uses fast growing softwood as the wood of choice due to it's long term stability within the walls.  Hardwoods, like oak, are a poor choice for the very reasons that you sited, that is, they will absorb moisture and swell, cracking the wall and in some case rasing the structure off the ground!  Softwoods, like cedar or pine, seem to have the ability to transpire the moisture through the log ends much better than hardwoods and after the mortar has set, become very stable, even after a hundred years or so.  There is some initial cracking around the logs in the first year, due to the logs taking on moisture from the mortar, but this is minimal (with the correct spacing of the logs) and an easy repair.

Also, in many cases, the log diameter ( 2" - 6") is such that they are considered waste by most paper and logging companies and would be shredded and turned to mulch, or worse yet, burned. Also, as in our case, we are looking at wooded lots that are in need of clearing to allow the trees the best chance of growing.  Fell wood, sick or overcrowed trees then become our cordwood.  In our case that is one of the major land decisions, that there be enough dead wood/need to be cleared wood, to build the home.  We will be using very little in the way of manufactured wood products (main post and beams being the exception).

Wood can be heavy, but is this case the wood length will be 16" with a diameter of no more than 6".  The 6 inchers will be split to allow for better contraction/expansion properties.

Also, we will be using a mix of paper with the mortar (ala papercrete) to slow the curing time and decrease the amount of cracking.

We are looking at a double wall construction, using cordwood exterior walls with cob interior walls.  The mix of the two should allow us maxium thermal mass and organic freedom in the interior design.

Hope that helps!
Hos
  ----- Original Message ----- 
  From: Yun Que 
  To: coblist at deatech.com 
  Sent: Thursday, March 06, 2003 09:05
  Subject: Re: Cob: cob and cordwood










  Cat here.  Been listing to the cord wood considerations and have some misgivings about the use of so much lumber, where stone or salvaged brick and block may be available?  Wood also has a real nature to suck up all the moisture it can get.  It will suck moisture and oil right out of your hands.  It moves when it does this and not the same as clay.  So wood must remain dry at all times to avoid cracking the cob.  Or at least at a stable humidity.  So much so that I won't install a cabinet in a home until the heat and air are working.  Is the interest in cord wood construction predicated on the idea that it is going to be easier?  big chunks of wood are heeeeaaaavy! 

  for the good of all Cat



  >From: Darel Henman 
  >Reply-To: Darel Henman 
  >To: Kim West 
  >CC: Cob List 
  >Subject: Re: Cob: cob and cordwood 
  >Date: Thu, 06 Mar 2003 17:10:27 +0900 
  > 
  >Kim, 
  > consider the old wattle and daub buildings of centuries ago and even 
  >today. The wood cob/daub mixtures melt well together. 
  > 
  > For a coordwood, like cob, however, you should provide a proper rock 
  >or other kneewall/foundation. 
  > 
  >Darel 
  > 
  > > Kim West wrote: 
  > > 
  > > Was wondering if it is possible to build a structure where the first 
  > > 3-4 feet are cordwood, then the remaining height of the structure is 
  > > cob? 
  > > 
  > > Or, if one were to build a cob structure with a cordwood addition, 
  > > what would be the proper way to connect the two materials without 
  > > problems due to differing shrinkage and settling rates? 
  > > 
  > > Anyone here had any experience building cob/cordwood hybrids? 
  > > 
  > > Thanks, 
  > > 
  > > Kim 
  > 


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<DIV><FONT face=Arial size=2>Cat,</FONT></DIV>
<DIV><FONT face=Arial size=2>You bring up some interesting points, which may or 
may not have relevence depending on your location and wood supply.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Cordwood traditionally uses fast growing softwood 
as the wood of choice due to it's long term stability within the walls.  
Hardwoods, like oak, are a poor choice for the very reasons that you sited, that 
is, they will absorb moisture and swell, cracking the wall and in some case 
rasing the structure off the ground!  Softwoods, like cedar or pine, seem 
to have the ability to transpire the moisture through the log ends much better 
than hardwoods and after the mortar has set, become very stable, even after a 
hundred years or so.  There is some initial cracking around the logs in the 
first year, due to the logs taking on moisture from the mortar, but this is 
minimal (with the correct spacing of the logs) and an easy repair.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Also, in many cases, the log diameter ( 2" - 
6") is such that they are considered waste by most paper and logging 
companies and would be shredded and turned to mulch, or worse yet, burned. Also, 
as in our case, we are looking at wooded lots that are in need of clearing to 
allow the trees the best chance of growing.  Fell wood, sick or overcrowed 
trees then become our cordwood.  In our case that is one of the major land 
decisions, that there be enough dead wood/need to be cleared wood, to build the 
home.  We will be using very little in the way of manufactured wood 
products (main post and beams being the exception).</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Wood can be heavy, but is this case the wood length 
will be 16" with a diameter of no more than 6".  The 6 inchers will be 
split to allow for better contraction/expansion properties.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Also, we will be using a mix of paper with the 
mortar (ala papercrete) to slow the curing time and decrease the amount of 
cracking.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>We are looking at a double wall construction, using 
cordwood exterior walls with cob interior walls.  The mix of the two should 
allow us maxium thermal mass and organic freedom in the interior 
design.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Hope that helps!</FONT></DIV>
<DIV><FONT face=Arial size=2>Hos</FONT></DIV>
<BLOCKQUOTE 
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
  <DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
  <DIV 
  style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B> 
  <A title=yunk88 at hotmail.com href="mailto:yunk88 at hotmail.com">Yun Que</A> 
</DIV>
  <DIV style="FONT: 10pt arial"><B>To:</B> <A title=coblist at deatech.com 
  href="mailto:coblist at deatech.com">coblist at deatech.com</A> </DIV>
  <DIV style="FONT: 10pt arial"><B>Sent:</B> Thursday, March 06, 2003 
09:05</DIV>
  <DIV style="FONT: 10pt arial"><B>Subject:</B> Re: Cob: cob and cordwood</DIV>
  <DIV><BR></DIV>
  <DIV>
  <DIV>
  <P><BR><BR></P>
  <DIV>
  <DIV></DIV>
  <P><BR><BR></P></DIV>
  <DIV></DIV>
  <DIV></DIV></DIV>
  <P>Cat here.  Been listing to the cord wood considerations and have some 
  misgivings about the use of so much lumber, where stone or salvaged brick and 
  block may be available?  Wood also has a real nature to suck up all the 
  moisture it can get.  It will suck moisture and oil right out of your 
  hands.  It moves when it does this and not the same as clay.  So 
  wood must remain dry at all times to avoid cracking the cob.  Or at least 
  at a stable humidity.  So much so that I won't install a cabinet in a 
  home until the heat and air are working.  Is the interest in cord wood 
  construction predicated on the idea that it is going to be easier?  big 
  chunks of wood are heeeeaaaavy! </P>
  <DIV></DIV>
  <P><EM>for the good of all </EM>Cat<BR><BR></P>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>>From: Darel Henman <HENMAN at IT.TO-BE.CO.JP>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>>Reply-To: Darel Henman <HENMAN at IT.TO-BE.CO.JP>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>>To: Kim West <KWEST at ARKANSAS.NET>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>>CC: Cob List <COBLIST at DEATECH.COM>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>>Subject: Re: Cob: cob and cordwood 
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>>Date: Thu, 06 Mar 2003 17:10:27 +0900 
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>> 
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>>Kim, 
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>> consider the old wattle and daub buildings of centuries ago 
  and even 
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>>today. The wood cob/daub mixtures melt well together. 
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>> 
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>> For a coordwood, like cob, however, you should provide a 
  proper rock 
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>>or other kneewall/foundation. 
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>> 
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>>Darel 
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>> 
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>> > Kim West wrote: 
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>> > 
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>> > Was wondering if it is possible to build a structure 
  where the first 
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>> > 3-4 feet are cordwood, then the remaining height of the 
  structure is 
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>> > cob? 
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>> > 
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>> > Or, if one were to build a cob structure with a cordwood 
  addition, 
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>> > what would be the proper way to connect the two materials 
  without 
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>> > problems due to differing shrinkage and settling rates? 
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>> > 
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>> > Anyone here had any experience building cob/cordwood 
  hybrids? 
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>> > 
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>> > Thanks, 
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>> > 
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>> > Kim 
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>> 
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV>
  <DIV></DIV></DIV><BR clear=all>
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