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cob house

Building With Cob

By Ashley

In All Articles
Jan 12th, 2018

Cob is one of the oldest forms of building materials. This is the combination of earth and straw. The oldest structure still standing is said to be 10,000 years old. It is the most sustainable form of a building. Uses 100% no toxic all natural materials. Cob is very durable. It is weatherproof and fireproof. It has also been tested to be earthquake proof, withstanding a 7.4 quake. Cob has high thermal mass( helps keep the temperature consistent). This material can be used for building homes, cob house, livestock housing, chicken coops, storage sheds, or even something simple like a pizza oven.

  The first thing you need to do is have land where you wish to place your new structure. Check with your local government to see if it is okay to build this type of structure on that land, according to your sates building codes. A nice piece of property in the rural country would be ideal, you will be more likely to be given the green light with little to no hesitation or complications. Once you are in the clear find a flat even spot to place your build. Fill in any potholes or uneven surfaces and pack down tight to ensure there will be no caving.

  Now you need to decide what kind of foundation you want. Concrete is great, or you may choose to build a cob foundation, either will work. Next, you need to gather the materials.


Sharp Sand



5 gallon buckets

  Most if not all these can be free. They can be collected off your land or from most foundation excavation sites. So If you take some time to find either of those you can start to build using little to no money. Of course if this is not an option you can buy them at all supply stores. The mix ratio should be 1 part clay, 4 parts sand, 1 part straw.

  Lets mix. you want to break down the soil(clay) by hand and let soak overnight in enough water to get a pudding consistency. Get the tarp and pour 5-gallon bucket of sand in center. Add one bucket of wet clay on to it. Add another bucket of sand. Mix with your feet. Smash and mosh the ingredients together. Form into a pile adding two more buckets of sand during the mixing process. Then sprinkle straw into it. Mix, mix, mix. Be sure to fold the mixture over using the tarp. Mix until the straw is evenly distributed. Make about softball sized balls. You will need to test your finished product by molding two of your cob balls together to form a brick or square. Allow to fully dry about one week to see if they are very strong.

  To assemble simply start by using one ball for the outside, one for the middle and one for the inside of your structure. Mold together. Continue until they are seamless and smooth. Wet your 1st layer of cob before adding more to it. Repeat this process until you have the structure you want. Whatever this may be, the process will be virtually the same. Cob doesn’t have to be completely flat, you can have curves or small bumps, it will just add to the artistic look of it. When you are done with your building you want to make plaster to even out any imperfections with two coats. Polish and seal it off with hemp oil.

 So there you have it. Cob can be inexpensive, durable and a great alternative to getting stuck on a mortgage or house payments. It will labor work no doubt about that but you will feel a sense of accomplishment and freedom. If you are interested in Cob I urge you to do as much research as possible. These are the bare bone basics to show you that self-reliance can be one step closer.

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