As my A-level Extended Project Qualification at I designed and built a wood-fired oven using the clay rich soil in my parents garden. It can reach temperatures of 400°C and cook pizzas in under 90 seconds! My main reference for this project was a great book called 'Earth Ovens' by Kiko Denzer.
TESTING AND FOUNDATION
I started by testing the quality of the sub-soil with a mini-oven. After lighting a small fire for a while it set rock-hard
(the clay rich soil around Cambridge is ideal for building earth ovens).
For the main oven I used large concrete blocks for the foundation and cast a
concrete pad as the base. Then I embedded lots of glass bottles inside clay slip as base insulation.
OVEN CHAMBER CONSTRUCTION
The floor of the oven is made of heat-soaking bricks and the walls are made from a thick clay slip. The sand mold which set the shape of the oven dome was removed once the first layer of clay had dried and a small fire was lit to cure the clay.
INSULATION AND FINISHING
Using more bottles and a clay slurry with wood-fibres in a thick insulation layer was added to the oven walls. A red lime render was applied to the oven to protect it from the elements.
The thick insulation helps retain heat, but the oven does needs to be heated for 2 hours before it reaches cooking temperature. Once at temperature, the oven can cook pizzas in under 90 seconds with a perfectly crispy crust!
