An Earthen Pizza Oven!

In September, Logan was a groomsman in Paddy and Anna Kinney's wedding in Boise, Idaho.

In November, we went back and built them an earthen pizza oven as our wedding gift to them...

The lighter color around the door is where the
plaster has already dried.
Eventually it will all be that color.

The door allows us to trap more
heat in while baking

In order to use the oven, you burn a fire inside for a couple of hours so the mass of the oven (cob) will retain that heat.  The hottest temperatures are good for cooking pizzas. After you are done with the pizzas, you can bake some bread, then bake cookies and muffins as the oven loses heat. It stays hot for about 12 hours!

First, we spent a few days finding and gathering materials.  We were able to get free clay slip from a pottery studio. We dug some sand from a nearby hill for free, and purchased some hampster bedding (wood chips) cheaply. We also purchased the fire bricks, a little piece of angle iron, wood for the door, and a few other things. We may have been able to find these things even cheaper or for free if we had more time to look, but in the end, we only spent about $60 on the project and built it in about a week.   

Logan had built an earth oven before in California, but this was my first one. We were also able to involve a friend that wanted to learn the process and had a lot of tools and resources for us. Thanks Justin!

We were happy to discover that Paddy and Anna had this large piece of concrete in their backyard that they were unable to remove, as it is an old agricultural well cover. It made a perfect foundation for the pizza oven and brought the height to a nice level. Here, I had just finished leveling the concrete with an application of cob.

We had gotten it in our minds that Boise would be dry and warmish in November, but instead we experienced quite a lot of rain and several nights below freezing.  ugh.  That slowed us down a little, but we pushed the edge of the building season and succeeded.

Here, we built a retaining wall and filled it with beer bottles and wood chips mixed with a little clay slip for insulation. 

Then we built a subfloor out of cob on top of that.  The bottles around the outside connected into the insulation that went around the domed oven at a later stage.

We laid the hearth (the floor of the oven), with fire bricks, made a dome out of sand over that and built the doorway out of fire bricks and angle iron.

Next, we covered the dome with wet paper, so the sand wouldn't get stuck to the cob that we layered on top of that and fall onto the pizzas later.. ]

Then came more cob (about 4") over the dome. Once that was completed, we dug the sand and paper out of the dome through the door.  Then, we made our first fire to start drying everything out. 

Making lots of cob!

This was so satisfying, to have a fire in there!

Next came 4" of wood chip/slip insulation and then an a half inch plaster (a thinner, wetter cob) layer to hold the insulation on. Lots more fire drying through this stage. 

Finally, I applied a 1" layer of finish plaster.  

Then, we were having 90 second pizzas and I baked an apple cobbler in about 10 minutes. awesome.  After the fire is out, the oven will hold heat overnight, so you can bake all day or have cinnamon buns in the morning.  

a month at The Strawbale Studio

I'm almost a month late in getting this out, but I was involved in so many awesome projects in Michigan, I want to share them...

The Strawbale Studio is the place in Michigan where the 2-week workshop took place that I wrote about building the small cottage. I returned there to work and learn from Deanne Bednar, the coordinator and with her other fall interns from mid August through mid September.

Ernie watching the pocket rocket burn off
the paint on the can. The paper mâche catches
some of the heavy metals from the paint

When I arrived, Deanne was preparing for two workshops with Ernie and Erica Wisner.  They came and did a Pocket Rocket workshop in Detroit and a Rocket Mass Heater workshop at the Strawbale Studio.  The Pocket Rocket is more of an emergency heater.  You can build it out of a large can and a couple of stove pipes.  Burning wood in it puts off a tremendous amount of heat and (after the initial burn) will burn a very efficient fire with no visible smoke.

Ernie with the inside of a rocket mass heater

The Rocket Mass Heater also burns a very clean fire, but it operates differently.  The wood fire is built in an area to the side and the draft of the system pulls the fire into the burn chamber (across the bottom) and up the heat riser (a chimney of soft insulated refractory bricks) in the middle of an external 50-gallon barrel.  The heat from the riser starts radiating out of the barrel at the top and the gasses begin to cool as heat radiates out of the barrel and the gasses drop down the sides.  At the bottom of the barrel, the hot gasses move into a system of stove pipe that is buried in an earthen bench, bed, floor, etc. before exiting out the ceiling, like a regular chimney. The idea is that, in addition to the radiant heat off the barrel, the heat from the fire exhaust heats the mass built around the stove pipe and then that mass holds the heat and slowly radiates it.  Even after the fire has been out for hours, you can sit on the bench and still be warm. It is better to heat a mass than heat air if you want to store the heat and access it over a longer period of time. Genius. Ernie and Erica have provided excellent information and drawings on them here... 

Deanne's Rocket Mass Heater
(the box on the barrel is an example of cooking on top of the barrel)

Ernie and Erica stayed about a week longer and it was interesting and enjoyable to spend that time learning and hanging out with them.

The earthen plastered door, drying

interior plastered wall

After that, I went to work plastering.  I decided I wanted more experience in this FANTASTIC and beautiful medium.  First, I plastered over the plywood walls of one of Deanne's little cabins.  She had built a rumford fireplace in there and wanted the surrounding walls to look nicer, be less susceptible to catching fire, and create a bit of mass to absorb some of the heat from the fire... earthen plaster does all of those things! I plastered the door, the wall, ceiling, and 2x4s that framed in that section. The plaster was made out of 1/8" sifted earth from the land (which had a combination of clay and sand), a little extra sand, dried and sifted horse manure (for fiber to hold it together), water, and a little wheat paste (white flour and water cooked into a paste). That little section gave me a lot of practice in going around corners, how much pressure to apply, what it takes to make sure the plaster is sticking, and more.  It was fun and I think it looked really good.


Two other interns arrived and we all set to work plastering another coat on the retreat cabin (the little cottage from the workshop).  The strawbales we used were really loose and uneven (apparently due to the drought this year), so this cabin took a lot more coats of plaster to even out the surface than your standard strawbale building...

 




Later I made 3 panels (on plywood) with earthen plasters and a little kaolin clay (the white part) to experiment with sculpture/relief images... Amazing how artistic you can be.  Your imagination is the only limit.  I didn't finish working on them before I left, but here's the beginnings.               

When the interns arrived, we all went to the Renaissance Festival together. A woman I had met from a Strawbale Studio tour painted my face and we saw some shows. We met some interesting characters too. This man had massive pickle sales...

After the rocket mass heater workshop, we learned so much, that we went back to the one that Deanne built a few years ago and made some modifications. Mainly, the distance between the barrel and the top of the heat riser should be between 2" and 2.5". Since we were adjusting this, we also built a little cob bevel on top of the heat riser so the ashes would fall to the bottom instead of getting caught on top and interrupting the flow of gasses. Then we replaced the earthen sill and seal around the rim of the barrel and voila - improved rocket mass heater!

Cob Tiles in Frames

Earthen Plaster, and Kaolin Plaster
(with different fibers)

Oliver (an intern) and I decided to make floor samples, so we could see a wide variety of applications and what the differences would be.  This turned into a pretty big project.  We made 12 small tiles (after making little wooden frames for them) out of cob (clay, sand, fiber and water) and then applied various finish plasters to them including earthen plaster or kaolin plaster (with white clay and sand), then a thin layer that included an earthen pigment (an "alis").

Look at all the varieties we tried (a small sampling, really)

We included some mica (shiny mineral for strength and prettiness).

We even did a little wet fresco!
(Now I understand how all those Italians I studied made their paintings!)

gravel, lava rock, slip straw, cob

I'm hoping Oliver did the linseed and/or hemp oil coatings (hardening coat) and will let me know how those turned out (that is the last stage of these samples).

Oliver also made a subfloor demonstration model so people can see different ways to build a subfloor below the earthen plaster finish layers.





The biggest project we undertook was working on the Kid's Cottage that Deanne built several years ago.  During the Rocket workshop, Ernie and Erica had the participants make a few changes that would help it run efficiently. Then the other interns and I secured the stove pipes in place, made a small cob wall to separate the floor space from the insulation under the benches, and installed the insulation (a perlite/vermiculite clay slip mixture) and began adding cob that would form the benches. This was a long process with a lot of learning along the way. In the end, we decided we should have just added the perlite and vermiculite without any slip and that is what we did towards the end.

Perlite/Vermiculite Slip Insulation

Small cob wall to separate insulation from floor area

Cob over the insulation to start the bench area

mixing the insulation for the Kid's Cottage

Some other interesting and fun endeavors... 

Milking a goat!

  * I learned to milk goats with one of the neighbors.

Making a Living Roof

  * We built half of a living roof on the wood shed (plants growing in soil on
  a pond liner as the roof!)
  * Found the dimensions to install a metal roof on a future sauna building
  * Replaced some of the thatch roof on the spiral chamber (a tiny building that
  holds the composting toilet)
  * Learned a lot about plants and herbs. There is a huge variety on
  the property there.  I want to learn more about plants!
  * Learned some permaculture principles from a local expert in order to prep  
   the greenhouse for winter growing.

Oliver measuring sauna roof

The greenhouse before

The greenhouse after

* Made a framework for a "Ready-Up" Tent out of poles harvested from the property

* Had a knots and lashing learning evening including: Miller's knot, Trucker's hitch, Tripod lashing, Handle lashing, and Love knots! 

See lashing examples 

Handle lashing is Great!

* Began sculpting a new turtle earth oven at the Kensington Metro Park. 

sculpting the Earth Oven turtle with fall interns

The beginning of a turtle sculpted on an earth oven

"Rock and Roll" Cob Mixing

 As you can see, a lot went on during that time! Since then I've been to a wedding, a funeral, and done some amazing hiking in the Sawtooth Wilderness (near Boise, Idaho). I'll post a photo or two from that once I have them.

Let me know what you think!

Love and peace to you!

I built a stone wall!

While I was visiting my parents, I had another little foray into natural building I thought I'd share... 

Vikki and Jay playing the course

My dad built a 18-hole "Hillbilly" miniature golf course on their land several years ago and this year we had the idea of building an interesting addition of a stone and cob retaining wall on one of the holes.  

We surveyed the course and thought we'd go with the hole that had the least amount of water run-off moving through it (the whole course is on the side of a hill). That hole also happened to be the one with an older upgrade... "Pickle Face." Check out the tree on this hole!

The grassy spot by my dad is the new hole area

Then, we got to work collecting the materials for the stone part of the wall. Ultimately, we decided to save the cob part for another time because there wasn't time for it all. Since their long driveway is made of gravel and rocks, we were able to gather the drainage rocks from there.  There is also a creek at the bottom of the property, where we gathered the stones for the wall.

rubble trench

We dug a trench about 4" deep (since this isn't a structural wall or a wall for a dwelling, we thought we'd see what we can get away with - for those structures, you should consider digging below the frost line).

Then we added an old worn out tarp in the trench to keep most of the dirt and debris out of the drainage rocks.

Added the rocks, wrapped them in the tarp, and added some more on top so you wouldn't see the tarp. If I were to do this again, I'd use smaller rocks for this part because it would help with the stability of the wall when placing the rocks.

Then to the stacking.  These slate rocks looked fairly flat, but they had a lot of bumps.  It was really difficult to stack them, so I focused on the largest rocks we had, so I wouldn't need to make as many adjustments with small shims.  This was by far the longest part of the process and most frustrating, but the most fun too!  

Always checking for level

I even split a few rocks to make them flatter.

In the end, the wall turned out great!  Then my dad finished out the design with a log and board holding up the fill dirt that leveled out the course and installed two drainage pipes that make the hole a tricky one! If you get your ball in the middle, good job and good score.  If not, you are taking a trip into the woods!

Check out Pickle face and those drop offs!

I think this hole upgrade really takes the course up a notch in coolness :) Thanks Mom and Dad for the opportunity to build something at your house.  

If you're in West Virginia, swing by and give it a go... 

First time we played the hole!

Yeah, hillbilly golf clubs!