For the Love of Cob
What I did with my summer vacation: spent a week covered up to my knees in mud, built walls out of said mud, had a great time getting to know about fifteen other people working with the mud, and generally fell in love with cob.
Earthen building has been used all over the world to build shelter for mellinia. Cob, the technique described in this lens, became popular in medieval times and is most widely known as a traditional building method in the British Isles. This June I took part in a week long workshop discovering for myself why mankind is so crazy about building houses out of...well, mud.
Cob Workshop
Fun in the sun...well, in the shade of a tarp, mostly.
Components of Cob
So, it's just mud, right?
I swore I would never do this but here goes:
The Marion-Webster dictionary defines cob as: a mixture of unburnt clay and straw used especially for constructing walls of small houses in England.
Whew, glad that's over. So, what is cob, really? It's a fairly sticky mixture of clay, sand, water and straw that is stacked to create a form, such as a wall or bench. Unlike adobe, where the mud is dried into bricks before use, cob is stacked while still wet. As each layer is added to the wall it is pressed down into the layer below to create a solid, seamless mass.
sand, clay, and soil: the three earthen components of cob. (The rock behind them...
loose straw is added to the mix
putting cob on the foundation wall
Pass The Cob, Please
The word cob comes from an old word for lump or loaf of bread, because cob is often passed from person to person in bread-shaped handfulls. Check out the young cobber walking across the bottom of frame to see what I mean.
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Cob Dancing
Human powered mud mixing...it's a good thing!
The most popular way of making cob these days is to mix the ingredients in small batches by stomping them (aka "dancing in them") on a tarp. Why a tarp? It's not strictly necessary, but it's a great help when trying to fully incorporate all of the materials.
Here's a quick run-down on how to mix cob:
First, mix your dry soil ingredients on the tarp. You can turn it by lifting one side of the tarp at a time, like the videos below show. Or, if you have two people you can each grab two corners, lift the tarp off the ground and rock back and forth, combining the dry ingredients with the rocking motion.
Second, add water and dance! Stomp on the cob until the water is incorporated. While stomping, stop every so often to turn the cob by lifting one side of the tarp at a time.
Third comes the straw. Sprinkle it on the wet mix in handfuls and stomp in a bit at a time. You may need to add more water. You'll know you have the right mix when it stays together in a rolled-up shape when you turn it. The technical term for this is "the burrito." You think I'm kidding?
Check out these videos to get an idea of the stomping and turning. For a good introduction to mixing and building with cob, read this partly-free-on-the-web book, The Cob Builder's Handbook.
What You Can Make With Cob
Cob: It's not just for houses anymore!
Houses, benches, garden walls and outdoor ovens are the most common cob structures. The wet mixture of sand, clay and straw (or other fiberous materials such as wood chips) is very easy to manipulate and form into fun shapes. With a little imagination, you can create beautiful and functional works of cob art!
Here is an experiment that the Tryon people were doing with cob benches. Cob mat...
Gorgeous sauna they had at Tryon. Colors in the cob walls are made with naturall...
A wood-fired cob oven created as a face sculpture. Used to cook pizzas. 20th Bir...
Real Life Cob
Follow along as Ziggy blogs about building his cob house
Fetching RSS feed... please stand byThinking about building your own cob house? For a good intro on the subject check out the partly-free-on-the-web book, The Cob Builder's Handbook, for ideas about site planning and passive solar design.
Building with Cob
Watch out for "splooging"
Ok, so it's not quite that simple, but almost. Be sure to build level all the way across the top of a wall. Press your fingers into the top of the wet cob when you are building, to give the next layer a rough surface to key into. Oh, and splooging? That happens when you press too hard on the top of the wall and the wet cob smooshes out on either side. This can be fixed, but don't let it get out of hand.
Here's a video that shows some mixing and some building with cob.
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Cob, anyone?
A Good Hat and a Good Pair of Boots...
...and a good rain coat.
Many of people want to know what keeps a cob house from just melting back into the ground when it rains. After all, it's just dirt and straw, right?
In the UK, where centuries-old cob houses are still housing people today, they say to give a cob house "a good hat and a good pair of boots." I threw in that bit about the rain coat.
So, what does that mean? It means that a cob structure can last for a looooooong time if it has a well-constructed roof to protect it from falling rain, and a well-constructed foundation to protect it from ground water seeping up into the walls. That's the hat and boot bit. The rain coat? A good, weather resistant plaster, such as lime (as in "limestone", not the citrus fruit) or earth, is a good choice to protect the cob walls from water that does hit the side of the structure.
This house has a good example of all three. The roof has a good overhang to protect the upper walls, the stone foundation stops water from wicking up into the lower walls, and the white lime plaster is weather-resistant. (Photo found on GerryT's photostream on flickr.)
I Love Cob!
A great cobby blog
Check out this blog for inspiration and information on cob building, permaculture, rocket stoves, etc., etc...
Fetching RSS feed... please stand byRecommended Reading
The Hand-Sculpted House: A Practical and Philosophical Guide to Building a Cob Cottage: The Real Goods Solar Living Book
Here's the book that the workshop instructors suggested we read. It is published by a couple who founded the Cob Cottage Company in Oregon, where our instructors received their training. It's very indepth and leads you through everything from choosing your site to different roof options.
Amazon Price: $23.10 (as of 12/02/2008) 
Used Price: $20.44
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Building With Cob: A Step-by-step Guide
Amazon Price: $29.70 (as of 12/02/2008)
Used Price: $25.46
Usually ships in 24 hours
The Cob Builders Handbook: You Can Hand-Sculpt Your Own Home
Amazon Price: $16.29 (as of 12/02/2008)
Used Price: $14.42
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You Can Make the Best Hot Tub Ever: Relax! Warm Your Bones! Get to Know the Sky
Amazon Price: $11.21 (as of 12/02/2008)
Used Price: $7.97
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The Cobber's Companion: How to Build Your Own Earthen Home
Amazon Price: (as of 12/02/2008)
Used Price: $188.62
Get Muddy!
Workshops, apprenticeships, internships and jobs dealing with cob.
- The Cob Cottage Company
- Want to immerse yourself in cob? Here's the place. Started by the authors of The Hand Sculpted House
, The Cob Cottage Company is the authority on Oregon Cob, the system of building with cob developed in the United States. Learning opportunities abound here, and the occassional job is available, too.
- Yestermorrow Design/Build School
- Yestermorrow teaches intensive hands-on courses in sustainable design, building, woodworking, and traditional crafts. You may even be able to receive college credit for some of the programs in this Vermont school.
- Cob Projects - Cob Houses and Timeless Art of Cob Building
- The main emphasis on this site is inspirational pictures of cob projects. But, over to the left is a long list of cob-related links. In them you'll find all sorts of communities and organizations that have information or learning opportunities about cob. They've even got a link to a Canadian green jobs database.
Cob All Over The World
er, um...I mean, Building With Cob Worldwide. Or something like that.
Thoughts, anyone?
So...what did you think about this lens?
Thanks for visiting my lens! I hope you liked it. If not, that's ok, too. Feel free to leave me a comment either way. :)
OhMe wrote...
Very educational as I had never heard of Cob. Thank you for the info.
Posted November 16, 2008
SadieCope wrote...
My children have always wanted to build a fort. I'm going to show them this lense and maybe they'll be able to build something for themselves!
Posted November 01, 2008
TopStyleTravel wrote...
Different but interesting subject matter. Liked the 'African Earth' picture. Thanks for sharing.
Posted September 23, 2008
Portable_eBay wrote...
To much to learn, not enough time. I sure would like to own a cob house.
Posted September 23, 2008
CleanerLife wrote...
Never heard of Cob before, I honestly thought I was going to read about building with corn cobs!
(Sounds odd, but I was envisioning model homes made of dried corn cobs)
This was interesting, I've learned a lot!
Posted September 18, 2008
