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Planning Our Cob Building and Building the Drain, Foundations and Stem wall

Planning (or not planning!)

The planning of our little cob building was pretty 'cave man style'. After deciding to call the building Henry, Tom and I grabbed our spades, went to our allocated piece of land (Toms dad was brave enough to allow us to build on a bush clad piece of his land) and began to dig. Over the course of 3 days, we dug a deep trench for the French drain and foundations. Digging in solid clay is hard work!

After 3 days of digging we built the French drain. On top of the French drain, we concreted in the 4 posts that would hold up Henry's roof. We had to use these posts as New Zealand is an on a massive tectonic plate and prone to earthquakes. If you are not in an Earthquake Zone, it's fine to do away with the posts and use load bearing cob.

And that's when we realized that a little extra attention to planning can be a good thing...

We had actually begun building Henry on the neighbors property! In the thick bush of the region, it's easy to forget where your boundary lines are. Ouch.

Henry the second was born.

This time we laid the building out with string and even did a rough sketch of what the building should look like. Our planning skills were getting better!

Our cob cottage sketch....

cob house design

Laying out where our cob building would go....

string marker for cob building


Our Cob Cottage Was designed around the $40 window and $50 door we purchased second hand. We had two big windows which were a bit shabby, but would scrub up well. They would sit either side of the entrance door. Besides this, we decided to just "go for it" and see what was created. The results would be both weird and wonderful.


Leveling the Ground and Digging the Foundations

Leveling the ground was not something I'd considered in this project to be honest. A flat building site? Who needs one of those!? Turns out Tom insisted we did - and so the digging began. We excavated and hauled away what seemed like a million wheel barrows of clay.

Thankfully we had beautiful friends and family to help...


levelling ground for cob cottage


And before long, we were done... (Yes, I was VERY excited at this point!)

level cob building site


Then came time to draw out the stem wall/foundation/wall line with flour! This would need to be at least 30cm thick. From the bottom up it would become 1) drain 2) recycled concrete stem wall 3) cob wall. The drain quickly takes water away from the building, the concrete provides a durable base for the cob and the cob creates the beautiful wall. You can also use stones (mortared or dry stacked) for the stem wall which looks absolutely incredible. We went with 'urbanite' as it was free and plentiful.

cob stemwall foundation

And voila!

cob stemwall drain


The Drain

In order for the drain to work effectively, it needs to be dug in a way that allows any water that gets into the drain to flow downhill, towards the lowest point and then have a place to escape - away from the building. This makes sure that the cob stays lovely and dry. Cob buildings don't like to have wet boots.

cob stemwall

Then we set the old school brick drain in place, and concreted our posts in on top of it (making sure the concrete didn't drop through and block the cavity below).

cob drain

And then we broke up some remaining bricks and filled in the spaces...

cob building stemwall


Now the finger crushing work begins - An 'urbanite' (reclaimed hunks of concrete) stem wall...

Before starting the stem wall, I was super excited. I thought it was going to be easy... You put hunks of concrete on top of each other - right? How hard could that be?

Well it turns out recycled concrete is not such fun to work with. The stem wall took us ages to do (nearly as long as the rest of the project - roof and cob walls included!) and it was painful work. Every day we worked on it saw another bloody finger added to the list. I can most definitely say that urbanite stem walls are a character building experience!

Here's the broken concrete 'urbanite' stemwall, emering from the ground...

cob stemwall

We kept plugging away at the stemwall though, and eventually we laid the last piece of broken concrete in place. It was high fives all round!

I don't have a photo of the stem wall without cob... but here's a photo shortly after we started cobbing...

cob wall progress

You wouldn't believe that this little stem wall was such hard work! Keep in mind though that about that much again is buried beneath the clay.

And once the concrete stem wall was complete - it was the moment we had been longing for....

The cobbing!!!

Read about our experiences cobbing in my next update here.