Want to get Acquainted with cob.

[fraggin]

So, I'm curious. Curious enough to play in the mud, maybe see if I Can build a brick or two. It seems like it would be a cool technique to be familiar with. I would like to start out small with a few buckets of raw material at my place in the suburbs and see what I can whip up. I will need straw, clay and sand, right? Is there a logical way I could go about getting these three materials in less than truckload quanities? I know where I can get wheat straw, and bags of sand. But not sure where I could pick up just a bit of clay. I know the purpose is to utilize the free and availability aspects of the materials to make cob, but in the city, these types of things dont come together as easily as they do in the country.
Just wondering basically how to get my hands dirty with it, and hopefully things will stick and I will want to use cob everywhere I can.

[glenn kangiser]

Well - How about that.  I just made cob today... Bobcat style.  My favorite way.



The formula for nearly all types of earth building is 30% clay, 70% sand and gravel and for cob, water and straw to taste.  Enough water to make it mix well and enough straw to have some ion every handful.  If too wet you will not be able to stack it as high and it will shrink more.

You need to consider the aggregate that is in the clay also.  In my case it would be about 50/50 for the best but for this wall I am just using my natural clay and rock with straw added to hold it together.  Probably a bit short on the aggregate but it's not rocket science and the extra straw will hold it together like adobe.  Adobe may be just clay and straw but it will shrink more so is commonly made into mud bricks and dried.  See Jonni and Cecilia's Mud Brick home - Australia-on  this site.

Here is Becky Bee's book - most of it is here online - you can get the full book direct from her.

http://www.weblife.org/cob/index.html 

[sjdehner]

Hi!

William Comstock built an array of cob houses in Carmel, California in the 1920's. He's probably the most famous (and interesting) cob "architect" in the United States. He was an early conservationist who had a great respect for trees, which led him to cob design. The houses were also inexpensive and a great asset to people who needed houses during the Great Depression which was soon to arise.

Here are some examples of his design:





This one has an Asian influence:



Aside from developing an inspiring personal conservation ethic that preserved resources and led to houses that will stand for ages, Comstock developed an appealingly simple architecture.

The houses are also beautiful, which I think should be a major part of any conservation ethic in building since beauty will add to the longevity of a house. I think that this happens because by being beautiful, people will want to take care of them as long as possible. And if built properly, this should be possible for generations.

If interested, you can find other examples of Comstock's houses by performing a GOOGLE search.

If you decide on cob I'd be very interested to see what you design - the sky's the limit, as they say!

Shawn

[fraggin]

My first idea was to build a covered outdoor sitting area around a chiminea out of cob. But, my very first project will be building a few bricks.

[Jens]

We are going to be doing that very thing this summer (I hope), with an outdoor kitchen and eating area underneath a timber (or log) framed living roof.  Have never done cob before, but have read a few books and websites!  In my experience that is all it takes: read do, fail, do, fix, improve, etc.  I'll be interested in your results here.

[kyounge1956]

So, I'm curious. Curious enough to play in the mud, maybe see if I Can build a brick or two. It seems like it would be a cool technique to be familiar with. I would like to start out small with a few buckets of raw material at my place in the suburbs and see what I can whip up. I will need straw, clay and sand, right? Is there a logical way I could go about getting these three materials in less than truckload quanities? I know where I can get wheat straw, and bags of sand. But not sure where I could pick up just a bit of clay. I know the purpose is to utilize the free and availability aspects of the materials to make cob, but in the city, these types of things dont come together as easily as they do in the country.
Just wondering basically how to get my hands dirty with it, and hopefully things will stick and I will want to use cob everywhere I can.

You might not need to buy any clay.Try a shake test (directions available at http://davesgarden.com/guides/terms/go/842/ and elswhere) to check the proprtions of sand, silt and clay in your soil. Its quite possible that the soil in your backyard is suitable for cobbing as is. I don't recall exactlyand haven't found the info in a quick web search, but IIRC you want a clay content of somewhere around 20%. If your soil doesn't have enough clay in it, you may be able to buy small quantities from a ceramic supply store.

Hope that helps,
Karen

[ScottA]

Those houses are really cool. 

[glenn kangiser]

There are 800 year old cob houses in England.  It can really be interesting.

[Jens]

You know, I grew up about 30 minutes from Carmel, worked there installing security systems, and phone systems, and delivered bread there.  I saw a lot of rich houses, but don't remember any as cool as those.  Once I was into cob, I no longer worked there, and didn't know that they existed!  Oh well, I'm on the other side of the world now.

[considerations]

"I grew up about 30 minutes from Carmel"  Really?  So did I, in Monterey, from 1960 to 1970.....when were you there?

[Jens]

I grew up in Santa Cruz, was there off and on from 1979-2007.  Family settled there in the mid 50's.  I installed security systems in Carmel, Pebble Beach, and Monterey areas.  Then Salinas took off with tract houses, and all of my work was there, in the same three houses that were the only choices in the place.  A person can get very quick at that kind of thing, when you do the exact same house day after day!  Honeymooned in a rented 29 Ford roadster on Cannery Row, and 17 Mile Dr, eating a picnic lunch on that first Carmel beach, right at the end of 17 mi.  Used to drag race out on Dolan rd, in Moss Landing...ahhhh, those were the days!

[glenn kangiser]

I did the structural steel on the new Safeway in Carmel.

[considerations]

Those were some good times.  There were only about 25,000 people living in Monterey, there was no traffic congestion except in Carmel during the Concourse de Elegance and the Pro Am Golf Tourney.....Ever go to the Mediterranian Market in Carmel?  Yumm!

[glenn kangiser]

When I was in Carmel I was in work clothes.... something frowned upon there.... I couldn't go anywhere....

Like I cared ...

[waggin]

Another book to consider is:

"The Hand Sculpted House-A Practical and Philosphical Guide to Building a Cob Cottage" by Ianto Evans, Michael G. Smith, and Linda Smiley

I just picked it up from the local library and started reading it today.  So far, so good.  They talk a bit about building codes and permits as being challenges for cob building, and that most jurisdictions would require cost-prohibitive testing, just as I seem to recall seeing in Glenn K's underground house thread.  Unless you have a very enlightened building department, plan on doing this sans permit. 

[glenn kangiser]

That's the best way if you want to use cob - time tested and proven over the centuries, however it is not taxable....