It was a labour of love, involving blood (mud-&-straw clumps scratching up our hands), sweat (building under the Spanish summer sun) and tears (when a supporting structure collapsed for the 3rd time).
An outdoor oven is one of those things Babs and I nurse ambitions about having someday, in that yet-to-be-identified place where we will eventually settle down (along with a massive charcoal BBQ pit and motorised roast spit). So I jumped at the opportunity to learn how to build one… by actually building one, while WWOOFING at Anthony and Catherine’s finca in Orgiva, Spain.
Our reference guide for the project was Build Your Own Earth Oven by Kiko Denzer. One of Denzer’s main principles is to use recycled and/or foraged materials, so that cost of building will tax neither your pocket, nor the envioronment. The only materials Anthony bought were ~30 firebricks (a few spare) and a few pieces of slate. The rest of it was sand from the beach in Motril, clay fand rocks from nearby riverbeds, and dirt and straw from the farm.
The Base
Anthony had already completed the base when we arrived. It’s a ringed stone wall, filled in with rubble. Right at the top it has insulating layers of clay and sand. The stone wall is self-supporting, but the crevices have been plastered up tight with mud and clay to prevent wasps from building nests in the gaps (The stone wall must have looked like a luxe condo block for waspy property hunters). On top of the slate are the firebricks (built denser than regular bricks to retain heat). This is the cooking floor of the oven.
The Support Dome
Question: If you’re building a dome which has a base radius of 33cm and a height of 48cm, how many buckets of sand from Motril do you need? Answer: Many more than you think.
In any case, the shortage was a great excuse to do a day trip to the beach. To improvise in the meantime, we bulked up dome volume with an upturned bucket, a few rocks and lots of gravel. It might have been due to this makeshift base, or the coarseness of the sand, or the startling evaporation rate, or one of our sandcastle building techniques (as Babs and I hotly debated) but we had 3 major sandslides before completion.
Above: Babs VERY GINGERLY puts wet newspaper and sackcloth on the completed sand dome to help keep its shape while I hold my breath
The Baking Layer
This first layer of mud and clay is what absorbs heat from burning wood in the oven, then radiates it back onto food. We had too much water in the mix, leading to lots of “flab” from sinking clay (what is it they say about ovens resembling their makers?). After it solidified sufficiently, Anthony did some nip tuck, and we marked out the door and scored the roof to help it bond with the next coming layer.
Additional Heat Retention Layer
Again this layer is made of mud and clay, but with straw mixed in. You can build an entire house out of this stuff, as is the case in various pockets of the English countryside, Africa, Central America and more recently Gaza.
Getting the straw to bond evenly with the mud is quite the task (Denzer recommends you get all the kids in the family or the community involved). Two people walking on it took too long, so we eventually blasted music from the house to get things really jumpin’.
Cutting Out the Door and Hollowing Out the Oven
After running out of mud and straw for the day, we let the furry-winter-hat-looking structure dry out overnight. The next morning, Anthony and Babs debated about whether it was dry enough to cut out the door, and excavate the sand dome. Babs was convinced only after he personally conducted the very technical “squidge” test (3rd photo).
Above: For those of you trying this at home: If you’re going to use an upturned bucket to pad out your base, make sure it’s not too much larger than the intended height of your door!
Above: Team WABS, our hosts Catherine and Anthony, and our functionally finished oven
Drying Out the Oven
We now have a functional oven structure! There’s a 3rd layer (about 1-2 inches thick) that will eventually go on, but it’s mostly decorative. In the meantime, it’s time to start a little fire to dry out the oven from the inside. Babs and I can barely contain our pyro-glee as we slap together a clump of straw, twigs (2 sizes), a little log and a couple of pine cones for laughs. The team very graciously lets me light the flame. It burns beautifully. Babs and I spend the next hour just sitting on the floor staring at the flame and tossing in twigs and logs.
Our First Pizza!
Given we’ll be needing to crank out pizzas for ~30 people this Saturday, the (ahem) professional thing to do was to test-drive the new oven for Monday night’s dinner. Current cooking time for 1 perfect pizza currently takes 5-8 minutes. The assignment for Wednesday lunch is to experiment with timing of pizza entry and burning-log placement, to reduce cooking time and improve even-ness of heat distribution. I forsee Babs and I insisting on a lot of practice.
If only all projects were this delicious and satisfying.
World Wide Wabs 
It looks like you are living my dream. I am so happy. Straw mud and cow dung combination was used to build huts long before any where else in the world. Does the fire lit in the same chamber as the food ?
Yep, the fire is lit in the same place – it´s all swept to one side for making pizza, and swept out entirely for baking bread etc…
Look up the Indus valley civilization in India
[…] where on top of helping to maintain a 1,000 year old irrigation system first designed by the Moors, we built an outdoor mud and clay oven by hand. On our days off, we poked about in nearby farming and mountain towns, greedily inhaling the local […]
Well done, I have a similar project completing and I am wondering how dry it should be before the first fire.
We waited for it to dry out enough that we could remove the sand from the inside without it collapsing. After that, we didn’t wait any extra time before lighting the first fire. We figured that the fire would finish drying it out anyway!
Hope your oven goes well!