Rural Country Living ~ Build a Cob Home for Under $4,000

Rural Country Living

Build a Cob Home for Under $4,000

By Brian Liloia (Ziggy)

In the spring of 2007, I packed my bags for the Dancing Rabbit Eco Village of

northeastern Missouri to begin a life of deeper ecological and simpler living with a

community of like-minded individuals. I left the hyper-suburban landscape of northern

New Jersey to begin to learn how to live more for myself, more in line with the ecosphere,

and more self-sufficiently. I hoped to start a life in which I could provide more for myself

and depend less on buying and more on making, including things like growing my own

food, sharing resources with friends, and building my own shelter.

And in the spring of 2008, having settled into community life at Dancing Rabbit quite

comfortably, I made the great leap to build my own home from the ground up. I decided I

would build a cob house based on my experiences working on a kitchen with cob walls

that friends at Dancing Rabbit were building during my first year of residency.

Cob is an ancient, proven building technique practiced all over the world. It’s the simple

combination of sand, clay, and straw, mixed by foot, and applied by hand to form massive

earthen walls. Cob is beautiful, sculptural, natural, low-impact and sustainable. It is

intuitive, easy to learn and inexpensive. A cob home is built from materials straight from

the earth and allows its owner-builder endless freedom in way of design. You can learn

cobbing basics in a day, and although it is indeed labor-intensive, it becomes a labor of

love and what better way to build a home than by getting your hands and feet dirty in

the mud, without the need for noisy power tools or heavy machinery?

I designed a small home to be constructed entirely out of cob, with few manufactured

materials, and many local, natural and recycled materials that I could obtain and harvest

with minimal impact and cost. I broke ground in April of 2008 and immediately got

hooked on the construction process, reveling in the completion of a big task, seeing the

house take shape step by step, and learning as I went. I spent every available moment

at the site making my dream of building my own home come true as quickly as I could.

I began with staking the building site based on a scale drawing of the floor plans. This

gave me the opportunity to feel out the shape and dimensions of the future building, and

at this step I actually increased the size of the house a tiny bit, which I'm quite thankful

I did. Next, came hand-digging the foundation trench, a 18" deep by 18" wide channel

drained to daylight, with reclaimed 4" perforated pipe at the bottom and filled with

tamped gravel to grade.

For a foundation, I sourced a pile of 'urbanite' (think recycled chunks of concrete). Since

this part of Missouri is devoid of stone, urbanite makes a good substitute. I laid two

courses of urbanite above the trench, and the west side of the building got a third

course since it was significantly lower than the rest. I did not bother to level the

foundation, since the building has no frame and the cob sits directly on top of the

urbanite. I made a stiff clay/sand/ mortar mix to stuff the joints in the foundation,

opting to avoid the use of concrete because of its extreme embodied energy. The

clay/sand/ mortar has caused a couple of problems since moving in. It wicks moisture

very easily, but creative drainage work around the house seems to have relieved most

of this issue.

With the completion of the foundation came the biggest task of all: constructing the

massive 18" thick cob walls. The clay in my walls came directly from the land -- in fact,

it came from the foundation of another much larger building. (Our soil is straight clay once

you dig down a foot!) The sand was delivered by dump truck, nine tons at a time, and the

free straw came from local farmers. The walls themselves only cost $500 in materials not

including windows and doors, of course.

As the wall went up, I installed the windows, too, simply buried directly into the wall. I

sculpted cob shelves, nooks and crannies. I had not planned the location for the cob

shelves in advance. Instead, I designed them as the walls grew taller, based on what

"felt right". The beauty of cob lies in the ability to embellish with creative touches

such as these along the way. Three months of stomping dozens upon dozens of

batches of cob (219, to be exact) and sculpting resulted in the final wall height.

Along the way there was much tarping, as we had a record wet year (figures, the

year I decide to build a mud house without a roof in place first), which was truly

a hassle. Tarping the walls to protect them from the weather took greater and greater

effort as the walls got taller and taller. I have many memories of being awoken by

howling wind in the middle of the night and running to the house site to check the

condition of the tarps.

With the walls up to their final height and leveled, it was time to figure out how to

build the reciprocal roof frame. I was inspired by several homes I had seen online

with reciprocal roofs, gorgeous geometrical, spiraling, self-supporting frames, usually

topped with soil. I obtained a copy of Tony Wrench's invaluable "Building a Low

Impact Roundhouse", which includes an important section on how to build a reciprocal

roof frame. Earlier in the year, I harvested pin oak poles for use as rafters, and I

assembled a team of helpers to arrange the poles to construct the roof. Unfortunately,

the poles proved way too flimsy, and I scrapped the original frame and went out to

harvest bigger and better poles. I spent a couple days felling and stripping beefy

black locust poles from my neighbors' land, and once again my volunteer crew and

I set about assembling the reciprocal roof (which is rather simple, I might add). The

second iteration proved to be much stronger than the first with its 14 large rafters.

The beauty of a reciprocal roof lies in its elegant simplicity: the rafters bear the weight

of one another, with no center support needed. The rafters form a gorgeous spiral with

an open inner circle, which I later topped with a skylight (more on that later). Later I

installed secondary rafters, one between each pair, to break up the span between the

primary rafters, and next I spent many hours decking the frame with 1x black walnut

lumber.

Over the decking went plain muslin fabric, to hide the cardboard that I next laid over the

entire roof. The muslin would be visible from inside the house, and the cardboard would

act as a cushion between the decking and EPDM pond liner. Before I could lay the EPDM

over the roof, I had to figure out how to frame the inner circle for a skylight. Thankfully,

in a flash of brilliance, someone suggested a tractor tire might fit the top of the roof, and

amazingly, I found one on our property that did! I cut it in half and laid it over the inner

circle.

It took at least a dozen people to carry the 300 pound piece of EPDM pond liner up onto

the roof, where it was unrolled like a giant blanket. At long last, the building had a roof

-- not finished, but at least it would protect the house from the weather. The next spring,

I cut the excess membrane around the perimeter of the roof and cut dozens and dozens of

sod squares from the ground of another building site, wheel-barrowed them to the house,

and hefted them up onto the roof -- again, with the help of more than a few friends. In a

morning, the entire house was covered in 4-6" of topsoil.

When the house had its unfinished EPDM roof, I began work on the earthen floor. I

decided to leave the topsoil in place, since it had been quite compacted throughout the

building season. Over the topsoil I piled on wheelbarrow after wheelbarrow of gravel.

I aimed for a 6" depth at a bare minimum on the east side (the higher side of the house),

and to make the floor level, I ended up dumping nearly 12" of gravel on the west side of

the house. To tamp the gravel, I hosted a dance party and encouraged people to stomp as

they moved around the house. Who said you can't mix work and play? With the gravel

sufficiently tamped and level, I mixed up some earth for the base layer of floor. My base

was a mix of sand and clay and long straw, with a ratio of about 3:1 sand/cay. Next time,

I'd include more clay for ease of installation, since it doesn't really matter whether the base

layer cracks at all with higher clay content. That base layer was 2.5" thick.

In the spring of 2009, I plastered the interior of the house in about four days with the help

of a friend, using a mixture of clay, sand, cow manure and cattail fiber. Unfortunately, the

weather was extremely humid at the time, so the walls took a fair amount of time to dry.

Once that was complete, I installed the finish layer of floor with a mix of sifted sand, clay,

manure and chopped straw. I did the installation by eye and used a steel trowel to make the

surface smooth. The final floor has some natural unevenness to it, which works out fine

with me. The floor took an age to dry (again, pesky humid weather makes drying miserable),

but once it was, I sealed it with four coats of linseed oil to protect it from damage and

weathering. This was the last phase before moving in on July 11, 2009, one year and three

months after breaking ground.

Since moving in, the house has undergone some changes. I originally designed and built

a rocket mass heater connected to a cob bed platform for winter warmth, but it completely

failed to draw sufficiently, so I ended up removing the tons and tons of cob and the stove

from the house. Now I have a small Morso cast iron stove for heat, which works to warm

the house as long as it is being fired. (Like all cast iron stoves, it doesn't store heat for very

long.)

A 2010 addition came in the form of a tiny mudroom, a small entryway space with a

second doorway to keep cold winter winds from immediately entering the main living

space upon opening the front door. This year, I plan on constructing a tiny greenhouse

on the south side for supplemental passive winter heating. I will remove the original

fixed south window and replace it with a sliding insulated window that opens into the

greenhouse to let in warmth on sunny winter days.

Building my own home has been the most rewarding experience I've ever encountered.

Not a day goes by that I don't look around my house and vividly and happily reminisce

about the construction process. I am so thankful to have had this opportunity, to have had

the help of dozens of people with construction and to be able to continue to learn and

experiment with improving and maintaining the house. To own a house by my mid-20s

is something few in conventional society could even dream of, but learning how to live

more sustainably and building with natural and recycled materials makes faraway

possibilities real and fulfilling. My cob house cost me less than $4000 (including the new

improvements) and has been the treasure of a life experience.

Ziggy lives at http://dancingrabbit.org Dancing Rabbit Eco-Village
and this is the Year of Mud http://small-scale.net/yearofmud Buy my book

Synopsis: The Year of Mud is one novice builder’s story of building his first cob house, a home

constructed largely of natural, local materials, many literally straight from the earth and surrounding

ecosystem.

A documentary story and inspirational guide for other individuals wanting to create more sustainable,

simple, human homes, The Year of Mud demonstrates one example of building that is intuitive,

inexpensive, earth-friendly, and creative. And muddy, too, of course.

Please visit Blurb.com to purchase my cob building book. To save 20% off, be sure to use

the promo code “NEWBLURB”. Thanks for supporting this project!