Saturday, June 7, 2014

The Cob House

Building with Cob

“Building with cob is a powerful political action, greatly reducing the need for the mortgage systems, lumber and construction industries, and petrochemical companies. Cob builders spend less of their lives working to pay for all of the above, and more time living. Making homes with natural materials gathered gently from the earth improves the likelihood of the survival of life itself.” (The CobBuilders Handbook, by Becky Bee)

“Cob is gentle on the planet. Using cob reduces the use of wood, steel, and toxic building supplies.” (The CobBuilders Handbook, Becky Bee)

Resources we're using:

The Handsculpted House, by Ianto Evans, Michael Smith and Linda Smiley
The CobBuilders Handbook, by Becky Bee (free pdf download)
The Tao of Cob, by Dorethy Hancock

We’ve cleared the ground, outlined the walls with stones, built a model more or less to scale. The shake tests of four different soil samples suggest that the dirt under our feet will make fine adobe or cob, with a good proportion of sand, about 50%, and perhaps 25% clay. We think we can gather grass stalks from Guy’s scything to use as straw to help bind the cob. Today we plan to start a trial wall, something small, to see how the cob mix holds up.

Location of new house, just a few yards from the first house we had built in 2012.
Stakes and tape outline the walls of the projected house

Soil from four sites. Bottom line indicates where sand settled within 5 seconds.  Next line up indicates where silt settled after 10 minutes. Above the second line the clay separates more slowly from the water. 

Here the water has been poured off - a good ratio of sand to clay.

Sofia starts clearing the area. Fofo, the cat, wants to help.

Hard work but nice as the afternoon cools off.

Greta finishes the clay model of the cob house.

Front door - two bedrooms, a living area and the bathroom.

First experiment making cob.
Third attempt with a larger amount of earth. This came out well.

Foundation for a cob bench - our first trial project.

Working in the cob.

Bench is about a third done.

We have an offer from an architect from Panama who currently lives in Brasilia (about 70 miles from here) to help us for a day or two. His father, also an architect, will be visiting from Panama and has expressed interest in what we’re doing. What a gift! We hope they’ll look at our plans and the tiny progress we’ve made, and help us with their observations, especially regarding the roof, which we haven’t been able to envision so far.

Will it work? No one around here makes cob houses - there isn't even a word for cob in Portuguese. In the past adobe bricks and wattle-and-daub were common materials for farm houses, but now baked bricks and cement prevail. We would love to show that we can build a very nice house for next to nothing. We hope it looks something like the house pictured below, thought the Kansas grandmother who built this house spent quite a bit because she paid for a lot of labor and purchased really nice extra materials and fixtures. 

Photo from the cover of The Tao of Cob, by Dorethy Hancock