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The Frugal Homemaker - Outdoor Wood Burning Oven

Updated on February 19, 2012

Building A Cob Oven With Kathryn McHolm

Last summer I attended a workshop "Build an Outdoor Adobe Earth Oven with Kathryn McHolm" at Wholearth Farmstudio hosted by Montana Jones. What an amazing adventure! I'm planning on using my new found knowledge to build my own "Earth Oven" this spring.

I'm looking forward to creating my own oven and incorporate glass and stones in the design. The oven door is something I am really looking forward to making as I plan plan to carve my own design into the wood.

Building your own cob oven is an inexpensive project that requires some elbow grease, but widely accessible materials. Dirt is cheap! The end result is an oven where you can bake the most amazing artisan breads and pizza, along with many other meals like casseroles, veggie stews and deserts.

Beautifying A Cob Oven


Kathryn McHolm - The Instructor

Kathryn McHolm has built several ovens and has been featured in Harrowsmith Country Life and Firefly Book's Living the Country Dream. Kathryn is an artist who works in watercolour, draws, gardens and work with fibres to create works of art that truly inspire people to get their artist on!

Her home is situated in Welcome Ontario, just north of Port Hope is located in a beautiful setting, surrounded by gardens, her earth ovens and art barn/studio at the back of her property. amongst beautiful trees, barns, and winding garden pathways. Kathryn continues to write how-to articles for "Harrowsmith Country Life"and since the 1990s her gardens have been included in books and magazines.

The photo above is of Kathryn (in the ball cap - she made from recycled socks!) giving us instructions on how to start or earth oven.

Getting Started


Recycled bricks were used to create the foundation for the oven. They needed to be tightly arranged so that little space was left between them. It was kind of like assembling a jigsaw puzzle, because the bricks were once used, some were slightly larger or smaller. After all the brinks were laid on the platform, mud was used to grout the cracks. Once this was finished to Kathryn's satisfaction a layer of mud was added to coat the bricks and provide a nice solid base for breads and piazza to be baked upon.

Laying the bricks for the foundation


Adding Branches To Make The Ribs


If you look at the photo you can see after placing the first round of mud and straw, branches were placed inside arced between the bricks. Eventually as more branches are added and woven together, a little bit of twine was used to make sure the structure was solid and could support more clay.

Once the oven is vitrified, all the branches and string will be burned out and the ashes removed.

Adding A Coffee Can To Create The Vent


As we moved along and built up the sides, it was decided to reinforce the walls with some wood until the clay had a chance to dry. The weather was ominous, and looked as though it could rain, and most likely would in the next day or so. After the oven was finished, a tarp was used to cover the oven to allow for drying in the event of rain showers.

Once the back wall was high enough, Kathryn showed us where the coffee can went, acting as a chimney. There is no need to add a chimney that floats upward in this design, simply removing the can before firing was all that needs to be done.

Creating The Opening For The Door


In this photo you can see where a bar of steel was placed to create an opening for the door. Montana would build a wooden door after the oven was fired based on the size of the opening after shrinkage once vitrified.

Bricks were used to help support the opening until the oven dried. The mixture of clay, sand and straw was a little off. The mix was a little too sandy, making the clay droop more than anticipated.

Mixing Clay, Sand And Straw


Mixing the ingredients was the labour intensive part. It required a smooth mixture, using hands to incorporated the clay into the straw. Hauling sand, and clay from point A to B required some back work, definitely worth the workout.

cob oven - double chamber cob oven

At the end of the day, after all was said and done, the oven was left to dry. Kathryn would return a few days later to vitrify the oven with Montana, the plan was to make some pizza! I was lucky to visit Kathryn at her home during a studio tour in July of last year. Her ovens were amazing, as were her gardens and art studio. I purchased a beautiful bird bath that she created that is shaped like a large leaf. The cafe tables and chairs, the whimsy of floating flowers and lemonade hidden in the shrubs made this a joyful and very memorable day.

Have You Ever Built A Clay Oven

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    leelee66 5 years ago

    Great information! Love the photos:) I want to make one!