My good friend Denice asked me for some help to work on her cob floor in her amazing cob building complete with bottle glass and cord wood walls. It also has a cob double chamber oven in the center of it limed to look like a giraffe.
My first time ever making or using cob, she took me through the (and did) whole process, from dirt, to water mix, to bentonite/ceramic clay, to sand mixing, to mixing with chopped barley straw, to application. Lots of fun.
In about 5 hours, we mixed, set and leveled about 250 gallons of cob as a second layer to the cob layer below (there was a lot of prior prep work over the past few days!!!). It was an awesome team effort! And I found a good technique for flattening/leveling the newly laid cob floor... a 14 inch 2x4, worked better than the soil packer and left a nice sheen. This will, eventually, once dried, get covered in a cob slip with cattail fluff... it'll be a few months out, and then linseed oil. I'll be helping with that part as well. looking forward to giving an update.
The whole floor consists of, 4 sheets of plastic, then sand, then 2 inch foam insulation, the rock about 10 inch deep, then native soil, then tamped, then a cob layer 4in, dried, second layer (3in) today, then the finish surface to come. and there was insulation put along the cement footers that is holding up the building... fun times!