The Fabulous Cob Oven Company

GDES3003 – GREEN DESIGN

Building our own Cob Oven

This week as a group we were asked to get our hands dirty and help with the construction of our very own Cob Oven on the University allotment grounds.

It’s amazing to think that the construction of the oven was completed over just 2 days. The intention was to have the test firing Friday evening, which in retrospect was a little ambitious particularly given the weather. We were helped and guided by Matthew from the Fabulous Cob Oven Company, who determined we should allow a week for the cob to dry properly. So this time next week we’ll be enjoying the fruits of our labours.

All in all it was a fun experience and will hopefully be put to good use for many years to come.

Notes from the build:

Cob is an ancient building material made from sand, clay, straw and water to help bind it all together.
The mix is generally 1 part clay to 2 parts sand, this is then trodden & turned to mix together.
A layer of straw is the added and the process repeated until it is well mixed.
You can test the mix by making a ball of cob with your hands and then doing the drop test. If it stay together then it is ready to go.
The internal dome is constructed out of sand which then gives a solid base and offers support for the Cob as it dries.
The Cob is then build around and over the sand dome until eventually it meets at the top to complete the structure.
Cob ovens are often given decorative features – We chose to make sun flare like flames that spread out from the doorway.
The mixture is then given time to cure fully before the archway for the door is cut out.
At this point the sand inside will also have dried and can simply be scooped out, revealing the open oven space.
As the exterior of the structure is also dry by this point t is possible to smooth the finish and carve the small details into the decoration.
Our oven will have a wooden door.