Building with cob is a long slow process when working alone (knowing from experience) but in the end it is satisfying and fulfilling. Traditionally Cob was a communal activity, once the design plan was complete and the materials were sourced everyone would get together to help mix and build.Usually this entailed music and dancing, from children to  elders everyone contributed. My process was a little different.

 

Location

 

To begin I chose an area and mapped out possible setups. Choosing my location was easy, my placement is halfway between the house and the garden with the wood shed a close 50 feet away. I set up next to a pre existing fire pit that was encompassed by flower and herb plants. Once my location was decided I began drawing and mapping the kitchen layout and the structure/shape of the oven.  

 

A Base for the Oven

 

It’s important for cob to have shoes and a hat, the shoes being a base. There are many different ways to make a base for your oven, from a well built wood table to a dry stack stone foundation. I choose garden pavers because they were what was available for cheap. I spent many hours looking through craigslist posts, checking used building/material stores and stopping at any garage sales I could find. In the end I found around 600 free garden pavers in seattle (was it worth the drive?). Hand loading and unloading some 500 brick by yourself turns out to be a long tiring process. Once I had measured and leveled out an area for the oven I began stacking the bricks, crisscrossing for stability.  

 

Sourcing and cob

 

Cob Consists of clay soil, sand and straw, you want soil with a high percent of clay, the sand to be very coarse and the straw thick and sturdy. I sourced the sand from our local Black Lake Quarry, 400 pounds for 20 dollars. The Straw was bought down the street from Kiperts korner at 8 dollars a bale (expensive!!). The clay was a bit more of a challenge, it took me a little over a week of chatting with people about the soil in the area. What places have a high percent and who needs 25 plus gallons excavated! I dug some up along the beach of eld inlet but was challenged by the steep uphill trek back to my truck. The north end of thurston county has a very high percentage of clay in the soil and I luckily knew a few people with property out there, I was able to excavate enough out there to proceed.    

 

Mixing the cob

 

The next step was to test clay to sand ratios. I knew my clay had alot of sand in it already so I tested a 1 part clay to ½ part sand, 1 part clay to 1 part sand and a 1 part clay to 1 ½  part sand. I shaped them into bricks and let them sit overnight, all the tests held up well but the 1:1 ratio felt strongest with the least amount of cracks. Using this ratio I mixed large quantities. This process can be slow when working alone but after many hours I was satisfied with my consistency. Breaking up the clay was first then on a tarp I mixed the sand and clay. Once they were well mixed I added water and got my feet dirty, dancing on top of the mix then rolling the trap to flip the goop. Last I added straw by taking small handfuls and sprinkling the straw while dancing on top of the cob (play some good country music to get in the spirit).  After the cob was mixed completely I began rolling it into balls and started sculpting!

 

The oven  

 

The last portion of the oven project is the sculpting. I first put down a level layer of cob about 3 inches thick. I then layed down used wine bottles (the same thickness) for heat insulation, surrounding the bottles with cob and making a flat level top layer of cob. My biggest purchase was Firebrick (15 bricks for 44 dollars), firebricks are straight sharp edged bricks without holes that can stand high heat. This is the floor of the oven using 15 bricks for a 21 inch diameter oven. To shape the interior I will use wet sand to make a dome. The sand will then be covered in newspaper for a barrier between the sand and cob. For a good interior layer I will use cob without any straw in the mix, about 4 inches thick with another 8 inches of cob with lots of straw for good insulation. Once dry but not to dry I will cut a hole for my door (angling the hole in so my door won’t fall through) and dig out all the sand, once I hit the newspaper i’ll know to stop digging. Finally I will cut a piece of wood in the shape of the door for a cover and use a thin layer of plaster (clay and sand) on the exterior for esthetics and weather protection. In future month I will need to build a shelter over the oven otherwise it will deteriorate over time.