Cob: Re: straw wattle

[andrea arnold]

     more info on the straw wattle from the photos I
posted....

      The building had a post and beam construction
with some framing.  The section we did was I think
about four feet wide between the studs.  looks like
those sticks were placed about a foot apart.  Sticks
were not stripped of their bark, I'm guessing they
were probably alder, we don't have a big variety of
trees on the island here.  The wall was 4 or 6" thick,
I can't remember.  It would have thermal qualities
similar to straw/clay or strawbale, something like R-2
per inch I think.   The clay used was a soil that was
primarily clay in content.  No sand was added.  Water
was added, clay was soaked. All lumps were broken up,
though not to the extent of how smooth we made it for
the clay plaster.  Water was added to the point that
it was very very very thick mud.  Picture something
like slightly runny oatmeal.  For example, if you
stuck your hand in it, your hand would come out with a
1/2" layer of clay on it.  
      Michael came up with this idea while helping
someone build there house in his community.  They went
out to collect sticks for wattle, and couldn't find
enough.  So they played around a little and figured
out you could just use long straw and clay to weave
back and forth instead of sticks.   Makes sense,
wattle panels are so pretty, but then you just cover
them with daub and never see the beautiful handiwork,
so why not just use something else, ya know?  
      As for warmth, it doesn't get extremely cold
here in the winter.  I'm not sure where you live
though, to compare.  I know you can do light straw/
clay up to 10" thick and beyond that you increase the
chance that it might mold/rot instead of fully dry.  I
would think maybe a similar guideline for the straw
wattle as well, but I don't know for sure.   
      A note on clay prep....We soaked the clay soil
in homemade pits consisting of 4 strawbales lined with
a sheet of plastic or tarp.  We tried to have it at
least soak overnight before using it, but there wasn't
always time.  We had four pits, and rotated through
them and filled them back up several times.  This
worked well, though it was surprising to me how much
clay we needed.  I always here how cob is more sand
than clay.  But with everything else we did - clay
slip to dunk bales in, clay slip for the light
straw/clay, clay for the earthen floor and plasters,
clay for the cob - I think we used more clay than
anything else (sand, straw, etc).
      Another thing that worked well as a building
site in general, was having lots of extra strawbales -
they were our seating, our step stools, and our
ladders in addition to our clay pits.  They came in
handy everywhere. 

- Andrea

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