The CCAT Earthen Oven:

An Engineering 305 Project.

   Materials Gathering and Preparation

                                                                               Liz poses at the Urbanite Resource Site

So where can you get the things you'll need to build your oven? Most of the stuff like shovels and hammers you can find at a hardware store, or sometimes borrow from friends. Other oven ingredients may require some more sleuthing. As a general rule, the closer the resource the better.

In addition to just getting the materials together, they need to be prepared. We grated and soaked a lot of clay, sifted a lot of sand, and grated a lot of manure ourselves, but also had a lot of this done during the educational work parties.

Looking for costs? Consider checking out our oven materials list below which includes prices, and additionally, our material origins.

Urbanite (concrete chunks): construction sites, calling local construction companies, looking for piles around town (ask before you take). Not much preparation is needed after you've harvested your urbanite. You may want to get a small sledge hammer to shape the chunks just the way you want. More about Urbanite in the Foundation Section.

Clay: It is best to dig on site.  You can dig up some clayish soil from below the topsoil in your yard and give it the "E-Z soil analysis test" here. Grate the clay on a heavy duty screen (1/2") to help break it up before it is mixed in with your sand or straw. Raw clay is easily mixed with a paint mixer after it has been soaked in a bit of water for a while (though our mixing attachment did break after a while). 

Sand: It is very important that you use river sand for construction with cob, beach sand is too smooth. You can get sand directly from the river, however try to minimize your impact to the river bank. You can also buy sand from construction companies that sell gravel. You want about 1/4 inch or smaller. We used varying sized screens (as seen below) to filter the sand to different sizes we wanted. Larger pieces of sand and gravel are welcome in the foundation to be used as fill. Medium pieces are good to mix with your clay. The finest sand is used for laying the fire brick and for a fine plaster coating.

Straw:  Usually you buy it unless you know someone in the bailing business. We bought organic rice straw for $5.00 a bale and needed about 2 bales.

Manure: A good ingredient in the plaster. Get from fields with permission. Call local stables for horse manure or dairy/meat farms for cow manure. Do not trespass on fields! Manure works great as a fiber because it has already been digested into very small particles which can form long chains of tensile strength in cob mixtures. Grate the manure to break it up from its post-digested form. Consider using rubber gloves or washing your hands afterward.

Fire Brick: Unless you find it somewhere creative, we suggest buying it from a place that sells brick and building materials. The bricks will assembled into a floor for your oven so it is important that your brick resource has kept the bricks clean and free from things you may not want eat later (such as chemicals). Others have also suggested building oven floors out of large pieces of stone such as slate. More about Fire Brick in the Oven Floor Section.

  John mixes clay with a paint mixer                                          Clay mixed in a bucket                                                 Liz sifts sand with a screen

Oven Materials List

     As you can see from the list, using donated/salvaged items can drastically reduce construction costs.

What's Next?

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