Natural Building with Cob, Earth Bags and Rocket Stoves
This summer the Laytonville Ecovillage hosted a natural building workshop during which we learned how to build with earth, and created several useful structures. Our workshop focused primarily on cob building, earth bag construction, and rocket stove hot water heating technology and was lead by Sasha Rabin and John Orcutt of Quail Springs Permaculture (quailsprings.org).
Cob building is an ancient natural building method that mixes clay-rich soil, sand, and straw to form an earthen material used for building walls, stoves, benches, and more. Cob is similar to adobe bricks, but differs in that it creates monolithic structures instead of masonry that is typical of adobe buildings. If you’ve ever seen a cob cottage, cob pizza oven, or cob bench they were all made using the same basic materials that are readily available and affordable. Although building cob structures is a common and fun learning project in most Permaculture Design Courses, to design and build lasting cob structures takes skill. (Our course is part of a larger “advanced skills” curriculum being developed at LEV.)
Traditionally, “natural building” may incorporate a wide range of techniques and materials, such as cob, adobe, timber framing, classical masonry, thatch roofing, etc., depending on what is appropriate for a given site.
The dynamic five-day intensive was an introduction to cob building, adobe brick making, and earth bag construction, and Sasha and John discussed a wide range of earthen building techniques. We also learned about rocket stoves and rebuilt the Laytonville Ecovillage’s rocket stove hot water that was designed by Kirk Mobert of Sun Dog Natural Building (sundogbuilders.net). Its exterior was damaged by last year’s torrential fall storm but the interior was intact and usable, requiring only that we redo the exterior. We also got a base coat of plaster on the rocket stove. The rocket stove heater will provide an abundance of hot water during the colder season when sunshine for the outdoor solar shower is in short supply.
Clean burning and highly efficient, rocket stoves are increasingly popular in cob buildings. Rocket stove innovations are developing at a rapid pace—to say that the rocket stove movement is “on fire” would be an understatement! We had a nighttime demonstration on the effects of adding proper flue/chimney piping to a demonstration burn barrel and simple camp fire and could really hear the “rocket” sound when the draft was just right. This also, and importantly, demonstrated how clean and smokeless a properly drafted fire can be!
The second structure we started is a round cob garden shed with an earth bag, or “superadobe” foundation. Developed and refined at Cal Earth (calearth.org) as an earthquake resistant form of natural building, superadobe uses on-site earth and very few tools. Short or long sandbags are filled with moistened earth and arranged in layers of long coils. After compacting with a tamper, strands of barbed wire are placed between each layer to increase seismic resistance. The earth bag foundation also elevates and prevents moisture from wicking into the cob walls, and will not easily erode since the earth is contained by the sandbag.
Earth bags can also utilize small rocks and granular material, which the Laytonville Ecovillage has an abundance of from a concrete foundation salvaged from an old structure we had to take down. Instead of throwing this material into landfill we have used it for various projects and it worked perfectly as a reconfigured foundation material. (No waste!)
The garden shed will make for an attractive and useful structure and demonstrate more natural building at the Laytonville Ecovillage. If you’d like to come and help us finish it please get in touch with us at firstname.lastname@example.org or call 707-984-6536.