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This is a badge bit (BB) that is part of the PEP curriculum.  Completing this BB is part of getting the sand badge in Natural Building.

Cob is a very useful material. You can build a house with it but you can ALSO use it as an all around patch and filler material.

To get certified for this BB you must:

  - use a low grade cob as filler between logs in a wofati
  - Must be a minimum of 20 linear feet of filler

and post the following pics:  

  - the before pic
  - the cob being prepped for use
  - the cob being put into place
  - the final result
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Approved BB submission
Ok, I did this one yesterday at the PEP1 event while working up at Allerton Abbey.  I was working alone so I couldn't get pictures of myself doing the stuff.  Plus there was muddy cob all over me so I didn't want to dirty up my phone.

Low Grade Cob is just dirt and water.  No straw and no additional clay slip.  Or at least the dirt here has enough clay for it to work.  I sifted the dirt through a 1/2" hardware cloth sifter and mixed it in a bucket with a small amount of water.  

Normally this BB would be easy, slapping cob up in the gaps/chinks of a log wall as you build a wofati.  In this case, the wofati was already built and the cob had to squeeze between log gaps and/or through 1" holes to get to the other side of the wall.  I make a plunger tool that kind of helped.  Anyone else doing this under "normal" conditions will probably get the job done in 1/3rd the time since access will be much better.  I also used a big pastry bag to squirt the cob into gaps.  I made it extra soupy so it could be plunged/pastried into place.  (Hint) If anyone else is doing this same job at the abbey, sift your soil down to 1/4" or smaller so the pebbles don't plug up your applicator(s).

I did about 22' of linear cob on this project.  I photoshopped red lines on each log above where the cob was applied so you can see where it worked.  I skipped the middle of the wall since there's a big post on the dirt side of the wall that creates a huge void.  Filling that will probably take a 2-3" hole at the top and a couple wheelbarrow loads of sloppy cob and a funnel contraption.
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Allerton wall at the beginning with holes
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Cob mix in right bucket, hoe and spare dirt bucket
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Homemade plunger tool and pastry bag
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Allerton wall with >20' of cobbing on the back side (red lines are above each section that was done)
Staff note (paul wheaton) :

I updated the requirements a bit. We happen to have a spot that produces what we call "shitty cob" - a near perfect mix of sharp sand and clay. With a little water it makes a low grade cob. That is what you were using.

I certify that this BB is complete!

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