First Bread and a Meltdown

A major milestone achieved: we baked our first bread in the cob oven. As was to be expected, we can’t control the temperature very well yet and the oven was a bit too hot when we loaded the loaves. But better too hot than too cold I say; and with practice we’ll soon be able to get the temperature right.

Overall, I judge it a big success. We prepared 3 different foods: socca (a chickpea flatbread), whole grain sourdough bread, and a big pot of beans. The oven was plenty hot and retained the heat well – the dried beans were not pre-soaked but they cooked to perfection within a couple of hours.


I was very pleased with the baking performance. The “oven spring” is phenomenal and way beyond anything I can achieve in our gas oven. Instead of spreading and flattening, as whole grain dough is wont to do, the loaves rose and puffed up tremendously. I’ll be able to increase hydration of my doughs, achieving a lighter and moister crumb, and still end up with a nicely shaped loaf.


A minor mishap along the way: we melted our chimney. It turns out we were using double-walled gas vent pipe instead of double-walled chimney pipe. The former is lined with zinc which melts 419C / 787F. Clearly we exceeded that significantly and ended with a puddle of zinc on the hearth. Luckily zinc isn’t a toxic heavy metal, so we just scraped it off once it had solidified again. We can still use the oven – it now just has a single-walled chimney. But we will need to replace that soon. Without any insulation it will get dangerously hot. On the bright side, this proves that the double-chambered design is doing its job and creating a sort of after-burner effect, greatly reducing the amount of emitted smoke.


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2 Responses to First Bread and a Meltdown

  1. Michel says:

    We finished our cob oven with a very similar design: double chamber with chimney under a roof (our old carport…). There is no building code for this so I’m struggling to find the right answer as far as what kind of venting to use. We build it at 4″ venting but there doesn’t seem to exist any 4″ stainless steel venting. It’s all 6 or 8. What did you guys ended up using? And how did you design the flashing to put it through you roof? Homemade or bought from a fireplace store? I would love to hear your solution! Keep up the great blog – the bread looks amazing. Can’t wait to fire ours up!

    • We ended up buying an insulated high-temperature chimney pipe from the fireplace store. Pricey, but having seen how much heat the oven can generate, we weren’t taking any chances. We used the standard type of flashing (came with the chimney pipe): a bigger collar at the base to cover the hole in the roof, and a secondary smaller collar above that; and lots of caulk. It’s held up so far.

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