Kent at Tiny House Blog notes that "you can build your own cob house with little money, but with lots of time and enthusiasm." He shows us 24 year-old Ziggy's cob (a mixture of straw, clay, and sand similar to adobe) with a footprint of 360 square feet built for under three thousand bucks. (Yes, that is $ 8.33 per square foot.)
* sand (just over 30 tons total) – $507
* gravel (about 13 tons total) – $177
* straw (16 bales) – $36 (most straw I used was free)
* black walnut scrap lumber – $100
* misc. lumber – $20
* windows – $220 (two casement, one double hung window)
* electrical – $28
* galvanized wire – $30
* nails – $100 (I couldn’t believe how expensive nails are)
* raw linseed oil (for floor) – $72
* EPDM pond liner $622
* polycarbonate for skylight $400
Of course there is a price: Time. Ziggy notes that
I started digging a foundation on April 19, 2008, and moved into GOBCOBATRON on July 11, 2009. I effectively worked from April to November of 2008, and then April to June of this year. In total, I estimate that I spent nine months working on my house, full time.
To build a cob house, you have to stomp cob, a lot of it. Ziggy says
I stomped 219 batches of cob (one batch of cob is equal to three 5 gallon buckets of sand, and 2.5 worth of clay, nearly 30 gallons of material) for the walls of my house by foot, with the help of over 75 work exchangers, visitors, and friends throughout the year.
The cob bed and bench took nearly 20 more batches of cob, almost 1/10 of the material it took to build the house itself!
Pretty spectacular work for an amazing price. Ziggy documents it all at The Year of Mud.