[Cob] Curious about the clay

[howard at earthandstraw.com]

The oldest continuously inhabited houses were built with subsoil(dirt) with a clay content. 
Attend a workshop to find out how to performance test your materials and mix.


Howard Switzer, Architect
668 Hurricane Creek Road
Linden, TN 37096
931-589-6513
www.earthandstraw.com
  ----- Original Message ----- 
  From: Robert J Churchill 
  Cc: coblist at deatech.com 
  Sent: Monday, May 11, 2009 1:17 AM
  Subject: Re: [Cob] Curious about the clay


  I know going in that it's not cheap but money really isn't a problem. What is a problem is I don't want to build a structure and have it fall down because the clay sucked. So I'm more interested in experiences with commercial clay or even quarry clay, not just dirt with clay in it.

  --- On Thu, 5/7/09, Henry Raduazo <raduazo at cox.net> wrote:
  From: Henry Raduazo <raduazo at cox.net>
  Subject: Re: [Cob] Curious about the clay
  To: rjc2000 at pacbell.net
  Cc: coblist at deatech.com
  Date: Thursday, May 7, 2009, 5:04 AM

  Clay is one of the most common substances on earth as such many people have it
  available for free. Just go outside and dig it up. With that said every part of
  the earth differs from every other part of the earth. Some people have very pure
  clay which shrinks drastically as it dries some have clay and silt some clay and
  sand. Others have no clay or so little clay their walls will barely hold
  together.
  If you do not have a good supply of naturally occurring clay in your area I
  would not recommend building with cob. A fairly small wall that I built in my
  house as a heat sink weighs 8 tons. I bought 4 tons of sand ($20.00 per ton) and
  mixed that with 4 tons of clay rich soil that came from digging out the basement
  of a near by house. The contractor was going to haul the soil 60 miles and pay a
  tipping fee to get rid of it, but I was willing to take it for free. Buying that
  much clay at a pottery place would be a bit pricey.
  Anyone who would be a natural builder must first be a scientist and then be an
  engineer. As a scientist you look around your building cite and ask What do I
  have? Rocks? Trees? Clay? All can be converted to building materials. Clay is
  one of the most versatile because it has so many uses as a plaster, load bearing
  material or refractory. You need to experiment to find the best mix. Sometimes
  you need to add sand sometimes just straw. You make bricks and then destroy the
  bricks to determine the best combination of materials.
  When you know the best combination of materials then you become an engineer
  and ask yourself "How do I make 8 tons of this stuff?" I like to mix
  with a rototiller on a slab. You may want to mix with your feet on a tarp. What
  ever. You need a lot of stuff to build a house.
  Ed
  On May 7, 2009, at 1:19 AM, Robert J Churchill wrote:
  > The word "clay" is used repeatedly but really where exactly is
  all this clay coming from?  I have no idea where I'm supposed to get all
  this clay.  For me, it would be easier just to buy clay from a ceramics shop but
  I don't even know if that would work.  I live in an urban area and it's
  not like we can just go out and dig up clay at a local quarry.
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