Building With Cob (a Basic How-To)

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Yesterday I took you with me to tour an enchanting homestead belonging to my friends, Niko and Brandi and their lovely girls.  Niko is a cobb builder by trade.  He owns the Colorado Cob Company.  He can build anything from a chicken coop to a two story house.  I’ll give you all of his information at the end so you can contact him to make you something wonderful for your homestead.

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These aren’t precise directions since I was talking with folks the whole time I was there but I was so intrigued by this form of building.  If you have been following my writings for some time you know that Doug and I have a great love of New Mexico and adobe structures.  Adobe is made by taking this same formulation and drying it in large bricks.  Cob is more freeform.

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Niko started with a 5 gallon bucket of clay that he sourced from a job site in town where someone was digging out a basement.  He added a 5 gallon bucket of sand (purchased and salvaged off of craigslist from the flooding in the area last year).

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The mix was sifted by hand to eliminate any large clumps or foreign objects like glass or nails.

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One person on each side shook the tarp, folded it, stepped on it quickly and then the next person would fold it, give it a stomp until it was combined.

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Then the fun began.  A well was made in the center of the dirt and water from the hose added to the middle.  Then children and adults alike stomped in the mud to create a pudding like consistency.

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More water was added and a person on each side repeated the process of folding and stomping.

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They did this until the form freely fell away from the tarp and looked like a burrito!  Doug and Chris were on the other side of the crowd chatting.  I could just see the ideas over yonder bubbling from them.  It will be great fun building our chicken coop and bread oven and whatever else they dream up.

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Straw was added in fine layers so not to allow clumps and this too was stomped in.  This creates a network of strength throughout the clay and sand medium.

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The children had so much fun blending with their feet.  The mix is done when straw can be seen in any clump that is taken off but no thick masses of straw.  It must be all well combined.

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The cob is added over a heavy foundation of large stones and then can be blended over wood outlines and mesh.  For an example he used a large stone by the garden.  Folks helped to blend balls of clay on top of each other using a slip if necessary to moisten and bits of straw to help blend.  A stick can be employed to help blend two masses together.  They created a fun little cat goddess.  The entire batch only made the cat goddess about a foot and half high.  So for large projects a cement mixer or other large piece of machinery may be used.

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The cob is left to dry a few days then a plaster is added.  A five gallon bucket of slip (a blend of clay and water to make a thin paint-like consistency and left to sit for two weeks stirring daily) is poured through two screens into a container.  A shovel is used to sift it though the strainers.

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Sand is then sifted through a screen and once a five gallon bucket’s worth is sifted it is added to the slip mixture in the container.

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A five gallon bucket of horse manure is added to the mix.  Shovels and a giant mixer is used to blend it into plaster.

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Niko through a ball of the plaster against the house as a demonstration of its solidity.

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This will be added to the cob structure to create a more protected structure.

Cob building is a project that allows the homesteader to make affordable structures that are unique and artistic.  But also allows the participant to play in the mud!

Colorado Cob Company (click name to be taken to website)

Nikolai Woolf

719-510-7566

He also offers classes and hands on workshops for any sized project!

One Comment Add yours

  1. juliepullum says:

    Very interesting! My parents house was built around the 1500s a timber framed building and what we call ‘clay lump’ and looking at this process it would seem quite similar it had straw and clay combined and whatever else they could add to the mix. It’s a beautiful building which is still standing. Some time in the 18/19th century the outside was rendered why we don’t know why quite sad really because if the outside looked like the inside it must have been quite striking, black beams and whitish clay. I look forward to seeing what you guys build!

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