How to make a clay oven
Clay, sand and bricks is all you need. Plus some willing feet.
We built our clay oven in 2006/7 following the inspiring Build and Bake course run by our friends at River Cottage. They ran the course under the instruction of Kiko Denzer's book, Build Your Own Earth Oven.
Building the clay oven was a hugely rewarding project and we have had many successful flat breads, pizzas and roast meats cooked in it since. Here are some of the things we have learned along the way:
1. The oven is made solely of clay and sand, so if it gets wet, it will transform itself in front of your eyes into a soggy sandcastle. We erected a cantilevered roof to keep it dry, but the roof is not quite large enough so on windy days it can get wet. No big deal to cover it with a tarpaulin, but with hindsight we should have made the roof larger.
2. We live in a clay area, but when I tried digging holes in the garden, none of the ‘clay’ was clayey enough. It was not the sticky, smooth stuff we needed. Fortunately, someone nearby was building an extension and had a skip full. However, I didn't think of saving any for repairs so when a few cracks appeared I needed to buy some from a farm in Leicestershire.
3. Getting the right mix of clay and sand is critical. As a rule of thumb, 5 buckets of plastering sand and 1 bucket of pure clay, will make 4 buckets of clay/sand mixture (strange but true). You need to pummel it with your feet for about an hour to get a good mixture, so get some help.
4. All the pizza oven books suggest sharp sand, but the sharp sand sold by builders merchants tends to be too coarse. Plastering sand is better. It is sharp, but not as coarse so makes a mixture which is much better bound.
5. Some designs suggest a chimney and/or door, but ours works well without either. I did make a nice rustic door, but I find it works best if a fire is kept going at the back of the oven, and obviously if you close the door and don't have a chimney the fire will go out.
6. It takes a couple of hours for our oven to get up to full heat, which means you need lots of firewood. Ideally these are small pieces of good quality firewood, like oak or ash. Softwoods like pine and willow are ok, but you will need a lot more to get the same heat. Joiners are a good bet for hardwood kindling, and they will also give you sawdust which you can use for the insulation layer mixed with clay slip.
7. The oven will get really really hot, so you will need to have a way of manoeuvering the wood and food without scorching your hands. A toasting fork is really handy for both, as is a thick oven glove.