Monday, August 31, 2009

Want Inexpensive Natural Housing Material? Try Cob!

I love things that are made from natural, organic products; and, am slowly converting my apartment into a space as natural is possible for an indoor environment. Besides using environmentally-friendly paint, I am removing my carpet and replacing it with cork tiles. I could easily move into a cob house. I would want just a tad more floor space; but, cob would work for me.

In Old English, cob was a root word that meant lump or rounded mass. Cob houses are made of clay-like lumps of soil, sand, and straw. Unlike adobe and straw bale construction, cob does not use bricks or blocks. Instead, wall surfaces can be sculpted into smooth, sinuous forms. A cob home may have sloping walls, arches and lots of wall niches.

Cob homes are one of the most durable types of earth architecture. Because the mud mixture is porous, cob can withstand long periods of rain without weakening. A plaster made of lime and sand may be used to windproof the exterior walls from wind damage.

Cob houses are also suitable for the desert or for very cold climates.

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 Brian's (or Ziggy's as his friends call him) 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.)

Ziggy (shown above) calls it the GOBCOBATRON and built it at the Dancing Rabbit Ecovillage in Missouri. I just love that name "Dancing Rabbit Ecovillage" - it sets my imagination on fire.

He provides a materials list:
* 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!

Ziggy documents it all at The Year of Mud.

The following videos show more elaborate cob homes. Cob homes can be absolutely lovely.

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