This weekend's workshop was on the topic of building with cob, and more specifically building a cob oven. We have a wonderful little cob oven in our backyard that is absolutely delightful for an aspiring or professional baker - especially if you like fires and working outdoors. We usually bake twice a week here, once to make bread and once for pizzas. The cob oven can also be used for baking all kinds of other things (cookies, pies, etc), plus roasting vegetables, drying herbs, making yogurt, and so on.
Cob is a mixture of sand, clay and straw (aprox 9 parts sand : 1 part clay and a little straw chopped into the mix for insulation value on one of the layers of the cob oven). Cob building is a very intuitive process and has been done in all parts of the world (i.e. earth building) in various forms - adobe, mud huts, cob cottages, and so on. It's an ancient building technique that anyone can easily learn. We like to recommend making cob bricks or balls before you start a project, in order to test your cob mix. There are only a few technical details to consider - the ratio of oven base to oven height; and the ratio of oven door height to height of dome. There are great books that walk you through the process step-by-step: books like Build your own Earth Oven by Kiko Denzer; The Cob Builder's Handbook by Becky Bee (a pdf version is here), The Hand-Sculpted House by Ianto Evans, and The Cobber's Companion by Michael Smith.
And for further inspiration, here's a slideshow we found online of handbuilt cob houses, cottages, garden walls, sheds, sauna, and several bake ovens...
Here are a few pictures from our cob oven workshop (with some participants getting muddier than others!), and baking pita in the oven: