My urban forest cob experiment part I

The "Fig House" by the Mud Dauber School of Natural Building (a past neighbor!)
The cob “Fig House” by the Mud Dauber School of Natural Building (a past neighbor!)  Cute as heck, eh? Check out their workshops and other projects at here.

I’ve been talking about building a cob house for long enough now that rather than questions like “how’s that cob cabin coming along?” I’m hearing “Are you still doing the cob cottage thing?”

Well, now, folks, ground has been unearthed. Backs have been hurt. Sweat has evaporated. I’m starting this project.

What is it that I want to create? A small cob “getaway” and guest-house in our back yard with (hopefully) solar-powered electricity and possibly a “pump” and tank for kitchen sink water.  A place where I/we can write/read/play music and house our guests, now that we live in the smaller ~550 square feet part of our main home.  The site is right outside our the “forest” portion of our urban dwelling, so there are nice views and there is plenty of South sun and West (and North) shade.

Researching cob building

What’s cob? Hint: It’s not corn’s mother-ship.  Rather, it’s an age-old building technique of combining clay, straw, and sand to make a strong (and inflammable) material that’s natural, chemical-free, and cheap as heck.  For some ideas of what is possible with cob, be sure to visit my cob PINS!

Though completely the unideal time of the year to build –the book I’m reading recommends starting in April or May — it was not possible to start breaking ground then due to our tour.

Have I mentioned that I do not know what I’m doing?

[I once built a dog house when I was around 20.  My dog refused to enter/use/look at it. There may have been some flooding. This ends my building experience. But I dug a lot of holes BITD at my Dad’s property in Greece (remember, Laki?).]

Speaking of learning and books, here is the one I’ve been going through ever since the sweet Vicki lent it to us (and – ahem – I owe her a new book – it’s way past borrowing at this point).

Very detailed and helpful book on cob and cob philosophy
Very detailed and helpful book on cob and cob philosophy


The authors built their “Heart House” for $500.

We also read a great starter book that Rob’s mom sent us, The Cob Builders Handbook by Becky Bee – a wonderfully illustrated quick read to get you started.

We are fortunate in this area (Triangle, North Carolina) to have access to a wonderful building school (aforementioned – the opening photo of the cob house is by this org) called the Mud Dauber School of Natural Building. Check out their workshops here.

So after years of reading and thinking about building a small cob house (technically “accessory structure”) I am happy to say that I broke ground today.

And breaking ground hurts.

Locating and measuring the site

Measuring the required 12'
Measuring the required 12′


In Durham, you can build an accessory structure on your property without a permit as long as it is no larger than 12′ x 12′ and only one story high. So, I set to measuring my chosen dirt space to see where that left us.

12′ x 12′ Square

The circle of cob will go within these bounds – keeping in mind that the walls are very thick, thus minimizing space further.

Playing (cob) house

It was helpful to do a trial run to see where we’d put our various “rooms” within this tiny space.

Kitchen on the SW (far left) corner – complete with burners and bucket sink;  door on West side, bedroom North, then rounded cob couch sitting space on the East and South sides (for morning sunshine)


It was a little easier to picture with Rob in the  “bed” of the bedroom:

Rob, relaxing
Rob, relaxing


Quote: “I don’t WANNA get on the ground.”


Testing the site: soil and drainage

My first ground-breaking was to dig out about 3 feet of soil to test the drainage of the site. During this process, I also made a second test, using the dirt to test the soil. This second process of soil testing will show you how much clay vs. sand vs. silt you have.

Basically, you fill a jar with 1/3 – 1/5 soil, add some salt (or dish soap), water to the brim, then shake like heck.

First jar
First jar, shaken (DEFINITELY NOT stirred!)


After about 10 minutes, it looked like this:

10 minutes later
10 minutes later – some settling has occurred


What does this mean?


Folks, I have no clue.

I read the page describing the test over and again.  (But it sure felt scientific.)

Today I dug two mistake holes (where I didn’t really want them) and then two purposeful holes that are exactly where I’ll be digging a trench for drainage.

Rather than the recommended three feet (that’s cray!) I dug about 1.5 feet.  Then, I added water to monitor draining after 10 minutes; another two gallons after an additional 10 minutes. It wasn’t looking great (except to mosquito larvae):

Testing the drainage
Testing the drainage: fail?

But possibly this lack of fast drainage is due to the shallower-than-supposed-to-be hole I dug.

In any case, we’re making sure the home drains properly by building a trench with a slope downhill, adding perforated piping, and gravel below the foundation wall.

In the meantime, I dug another hole with my trusty pick-axe and shovel at the lowest point of the home’s wall:

Second test drainage hole
Second test drainage hole – right in the bedroom!

Back permitting, I plan to work on this most weekday mornings when it’s not quite as hot.

I’ve often thought about how our workouts, by which we strain, lift, push, and run to only one end, our health – should somehow be combined with an actual end result – such as helping someone build a structure, cleaning, farming (fruits & veggies of course!), winning wrestling championships, etc etc.

So, for now, this is also my “workout” plan rather than the YMCA – and if the damp shirt is any indication, it might just be a great plan.

Sweat (not cool)


My next step will be building the drainage trench – a lot of pick-axing and digging.  I’ll post updates here.

But I’m happy with my progress today.  In fact, my confidence in this project blossomed  when Rob took a look at my site and said, “I knew I should have helped you!”


TOTAL COST to date (July 31 2015)

$2 (wood frame for over door, and hanging wooden dish rack @ Rescue Mission Thrift Store)

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